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diff --git a/NEWS b/NEWS
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@@ -1,1179 +1,1180 @@
Noteworthy changes in version 1.9.0 (unreleased) [C22/A3/R0]
------------------------------------------------
* Interface changes relative to the 1.8.0 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcry_mpi_get_ui NEW function.
+ GCRYCTL_AUTO_EXPAND_SECMEM NEW control code.
Noteworthy changes in version 1.8.1 (2017-08-27) [C22/A2/R1]
------------------------------------------------
* Bug fixes:
- Mitigate a local side-channel attack on Curve25519 dubbed "May
the Fourth be With You". [CVE-2017-0379] [also in 1.7.9]
- Add more extra bytes to the pool after reading a seed file.
- Add the OID SHA384WithECDSA from RFC-7427 to SHA-384.
- Fix build problems with the Jitter RNG
- Fix assembler code build problems on Rasbian (ARMv8/AArch32-CE).
Noteworthy changes in version 1.8.0 (2017-07-18) [C22/A2/R0]
------------------------------------------------
* New interfaces:
- New cipher mode XTS
- New hash function Blake-2
- New function gcry_mpi_point_copy.
- New function gcry_get_config.
- GCRYCTL_REINIT_SYSCALL_CLAMP allows to init nPth after Libgcrypt.
- New global configuration file /etc/gcrypt/random.conf.
* Extended interfaces:
- GCRYCTL_PRINT_CONFIG does now also print build information for
libgpg-error and the used compiler version.
- GCRY_CIPHER_MODE_CFB8 is now supported.
- Add Stribog OIDs. [also in 1.7.4]
* Performance:
- A jitter based entropy collector is now used in addition to the
other entropy collectors.
- Optimized gcry_md_hash_buffers for SHA-256 and SHA-512.
- More ARMv8/AArch32 improvements for AES, GCM, SHA-256, and SHA-1.
[also in 1.7.4]
- Add ARMv8/AArch32 assembly implementation for Twofish and
Camellia. [also in 1.7.4]
- Add bulk processing implementation for ARMv8/AArch32.
[also in 1.7.4]
- Improve the DRBG performance and sync the code with the Linux
version. [also in 1.7.4]
* Internal changes:
- Libgpg-error 1.25 is now required. This avoids stalling of nPth
threads due to contention on internal Libgcrypt locks (e.g. the
random pool lock).
- The system call clamp of libgpg-error is now used to wrap the
blocking read of /dev/random. This allows other nPth threads to
run while Libgcrypt is gathering entropy.
- When secure memory is requested by the MPI functions or by
gcry_xmalloc_secure, they do not anymore lead to a fatal error if
the secure memory pool is used up. Instead new pools are
allocated as needed. These new pools are not protected against
being swapped out (mlock can't be used). However, these days
this is considered a minor issue and can easily be mitigated by
using encrypted swap space. [also in 1.7.4]
* Bug fixes:
- Fix AES CTR self-check detected failure in the SSSE3 based
implementation. [also in 1.7.6]
- Remove gratuitous select before the getrandom syscall.
[also in 1.7.6]
- Fix regression in mlock detection. [bug#2870] [also in 1.7.5]
- Fix GOST 28147 CryptoPro-B S-box. [also in 1.7.4]
- Fix error code handling of mlock calls. [also in 1.7.4]
- Fix possible timing attack on EdDSA session key. [also in 1.7.7]
- Fix long standing bug in secure memory implementation which could
lead to a segv on free. [bug#3027] [also in 1.7.7]
- Mitigate a flush+reload side-channel attack on RSA secret keys
dubbed "Sliding right into disaster". For details see
<https://eprint.iacr.org/2017/627>. [CVE-2017-7526] [also in 1.7.8]
* Interface changes relative to the 1.7.0 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcry_get_config NEW function.
gcry_mpi_point_copy NEW function.
GCRYCTL_REINIT_SYSCALL_CLAMP NEW macro.
GCRY_MD_BLAKE2B_512 NEW constant.
GCRY_MD_BLAKE2B_384 NEW constant.
GCRY_MD_BLAKE2B_256 NEW constant.
GCRY_MD_BLAKE2B_160 NEW constant.
GCRY_MD_BLAKE2S_256 NEW constant.
GCRY_MD_BLAKE2S_224 NEW constant.
GCRY_MD_BLAKE2S_160 NEW constant.
GCRY_MD_BLAKE2S_128 NEW constant.
GCRY_CIPHER_MODE_XTS NEW constant.
gcry_md_info DEPRECATED.
* Release dates of 1.7.x versions:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Version 1.7.8 (2017-06-29) [C21/A1/R8]
Version 1.7.7 (2017-06-02) [C21/A1/R7]
Version 1.7.6 (2017-01-18) [C21/A1/R6]
Version 1.7.5 (2016-12-15) [C21/A1/R5]
Version 1.7.4 (2016-12-09) [C21/A1/R4]
Noteworthy changes in version 1.7.3 (2016-08-17) [C21/A1/R3]
------------------------------------------------
* Bug fixes:
- Fix critical security bug in the RNG [CVE-2016-6313]. An
attacker who obtains 580 bytes from the standard RNG can
trivially predict the next 20 bytes of output. Problem
detected by Felix Dörre and Vladimir Klebanov, KIT.
- Fix building of some asm modules with older compilers and CPUs.
* Performance:
- ARMv8/AArch32 improvements for AES, GCM, SHA-256, and SHA-1.
Noteworthy changes in version 1.7.2 (2016-07-14) [C21/A1/R2]
------------------------------------------------
* Bug fixes:
- Fix setting of the ECC cofactor if parameters are specified.
- Fix memory leak in the ECC code.
- Remove debug message about unsupported getrandom syscall.
- Fix build problems related to AVX use.
- Fix bus errors on ARM for Poly1305, ChaCha20, AES, and SHA-512.
* Internal changes:
- Improved fatal error message for wrong use of gcry_md_read.
- Disallow symmetric encryption/decryption if key is not set.
Noteworthy changes in version 1.7.1 (2016-06-15) [C21/A1/R1]
------------------------------------------------
* Bug fixes:
- Fix ecc_verify for cofactor support.
- Fix portability bug when using gcc with Solaris 9 SPARC.
- Build fix for OpenBSD/amd64
- Add OIDs to the Serpent ciphers.
* Internal changes:
- Use getrandom system call on Linux if available.
- Blinding is now also used for RSA signature creation.
- Changed names of debug envvars
Noteworthy changes in version 1.7.0 (2016-04-15) [C21/A1/R0]
------------------------------------------------
* New algorithms and modes:
- SHA3-224, SHA3-256, SHA3-384, SHA3-512, and MD2 hash algorithms.
- SHAKE128 and SHAKE256 extendable-output hash algorithms.
- ChaCha20 stream cipher.
- Poly1305 message authentication algorithm
- ChaCha20-Poly1305 Authenticated Encryption with Associated Data
mode.
- OCB mode.
- HMAC-MD2 for use by legacy applications.
* New curves for ECC:
- Curve25519.
- sec256k1.
- GOST R 34.10-2001 and GOST R 34.10-2012.
* Performance:
- Improved performance of KDF functions.
- Assembler optimized implementations of Blowfish and Serpent on
ARM.
- Assembler optimized implementation of 3DES on x86.
- Improved AES using the SSSE3 based vector permutation method by
Mike Hamburg.
- AVX/BMI is used for SHA-1 and SHA-256 on x86. This is for SHA-1
about 20% faster than SSSE3 and more than 100% faster than the
generic C implementation.
- 40% speedup for SHA-512 and 72% for SHA-1 on ARM Cortex-A8.
- 60-90% speedup for Whirlpool on x86.
- 300% speedup for RIPE MD-160.
- Up to 11 times speedup for CRC functions on x86.
* Other features:
- Improved ECDSA and FIPS 186-4 compliance.
- Support for Montgomery curves.
- gcry_cipher_set_sbox to tweak S-boxes of the gost28147 cipher
algorithm.
- gcry_mpi_ec_sub to subtract two points on a curve.
- gcry_mpi_ec_decode_point to decode an MPI into a point object.
- Emulation for broken Whirlpool code prior to 1.6.0. [from 1.6.1]
- Flag "pkcs1-raw" to enable PCKS#1 padding with a user supplied
hash part.
- Parameter "saltlen" to set a non-default salt length for RSA PSS.
- A SP800-90A conforming DRNG replaces the former X9.31 alternative
random number generator.
- Map deprecated RSA algo number to the RSA algo number for better
backward compatibility. [from 1.6.2]
- Use ciphertext blinding for Elgamal decryption [CVE-2014-3591].
See http://www.cs.tau.ac.il/~tromer/radioexp/ for details.
[from 1.6.3]
- Fixed data-dependent timing variations in modular exponentiation
[related to CVE-2015-0837, Last-Level Cache Side-Channel Attacks
are Practical]. [from 1.6.3]
- Flag "no-keytest" for ECC key generation. Due to a bug in
the parser that flag will also be accepted but ignored by older
version of Libgcrypt. [from 1.6.4]
- Speed up the random number generator by requiring less extra
seeding. [from 1.6.4]
- Always verify a created RSA signature to avoid private key leaks
due to hardware failures. [from 1.6.4]
- Mitigate side-channel attack on ECDH with Weierstrass curves
[CVE-2015-7511]. See http://www.cs.tau.ac.IL/~tromer/ecdh/ for
details. [from 1.6.5]
* Internal changes:
- Moved locking out to libgpg-error.
- Support of the SYSROOT envvar in the build system.
- Refactor some code.
- The availability of a 64 bit integer type is now mandatory.
* Bug fixes:
- Fixed message digest lookup by OID (regression in 1.6.0).
- Fixed a build problem on NetBSD
- Fixed memory leaks in ECC code.
- Fixed some asm build problems and feature detection bugs.
* Interface changes relative to the 1.6.0 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcry_cipher_final NEW macro.
GCRY_CIPHER_MODE_CFB8 NEW constant.
GCRY_CIPHER_MODE_OCB NEW.
GCRY_CIPHER_MODE_POLY1305 NEW.
gcry_cipher_set_sbox NEW macro.
gcry_mac_get_algo NEW.
GCRY_MAC_HMAC_MD2 NEW.
GCRY_MAC_HMAC_SHA3_224 NEW.
GCRY_MAC_HMAC_SHA3_256 NEW.
GCRY_MAC_HMAC_SHA3_384 NEW.
GCRY_MAC_HMAC_SHA3_512 NEW.
GCRY_MAC_POLY1305 NEW.
GCRY_MAC_POLY1305_AES NEW.
GCRY_MAC_POLY1305_CAMELLIA NEW.
GCRY_MAC_POLY1305_SEED NEW.
GCRY_MAC_POLY1305_SERPENT NEW.
GCRY_MAC_POLY1305_TWOFISH NEW.
gcry_md_extract NEW.
GCRY_MD_FLAG_BUGEMU1 NEW [from 1.6.1].
GCRY_MD_GOSTR3411_CP NEW.
GCRY_MD_SHA3_224 NEW.
GCRY_MD_SHA3_256 NEW.
GCRY_MD_SHA3_384 NEW.
GCRY_MD_SHA3_512 NEW.
GCRY_MD_SHAKE128 NEW.
GCRY_MD_SHAKE256 NEW.
gcry_mpi_ec_decode_point NEW.
gcry_mpi_ec_sub NEW.
GCRY_PK_EDDSA NEW constant.
GCRYCTL_GET_TAGLEN NEW.
GCRYCTL_SET_SBOX NEW.
GCRYCTL_SET_TAGLEN NEW.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Version 1.6.5 (2016-02-09) [C20/A0/R5]
Version 1.6.4 (2015-09-08) [C20/A0/R4]
Version 1.6.3 (2015-02-27) [C20/A0/R3]
Version 1.6.2 (2014-08-21) [C20/A0/R2]
Version 1.6.1 (2014-01-29) [C20/A0/R1]
Noteworthy changes in version 1.6.0 (2013-12-16) [C20/A0/R0]
------------------------------------------------
* Removed the long deprecated gcry_ac interface. Thus Libgcrypt is
not anymore ABI compatible to previous versions if they used the ac
interface.
* Removed the module register subsystem.
* The deprecated message digest debug macros have been removed. Use
gcry_md_debug instead.
* Removed deprecated control codes.
* Improved performance of most cipher algorithms as well as for the
SHA family of hash functions.
* Added support for the IDEA cipher algorithm.
* Added support for the Salsa20 and reduced Salsa20/12 stream ciphers.
* Added limited support for the GOST 28147-89 cipher algorithm.
* Added support for the GOST R 34.11-94 and R 34.11-2012 (Stribog)
hash algorithms.
* Added a random number generator to directly use the system's RNG.
Also added an interface to prefer the use of a specified RNG.
* Added support for the SCRYPT algorithm.
* Mitigated the Yarom/Falkner flush+reload side-channel attack on RSA
secret keys. See <http://eprint.iacr.org/2013/448> [CVE-2013-4242].
* Added support for Deterministic DSA as per RFC-6979.
* Added support for curve Ed25519.
* Added a scatter gather hash convenience function.
* Added several MPI amd SEXP helper functions.
* Added support for negative numbers to gcry_mpi_print,
gcry_mpi_aprint and gcry_mpi_scan.
* The algorithm ids GCRY_PK_ECDSA and GCRY_PK_ECDH are now
deprecated. Use GCRY_PK_ECC if you need an algorithm id.
* Changed gcry_pk_genkey for "ecc" to only include the curve name and
not the parameters. The flag "param" may be used to revert this.
* Added a feature to globally disable selected hardware features.
* Added debug helper functions.
* Interface changes relative to the 1.5.0 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcry_ac_* REMOVED.
GCRY_AC_* REMOVED.
gcry_module_t REMOVED.
gcry_cipher_register REMOVED.
gcry_cipher_unregister REMOVED.
gcry_cipher_list REMOVED.
gcry_pk_register REMOVED.
gcry_pk_unregister REMOVED.
gcry_pk_list REMOVED.
gcry_md_register REMOVED.
gcry_md_unregister REMOVED.
gcry_md_list REMOVED.
gcry_md_start_debug REMOVED (macro).
gcry_md_stop_debug REMOVED (macro).
GCRYCTL_SET_KEY REMOVED.
GCRYCTL_SET_IV REMOVED.
GCRYCTL_SET_CTR REMOVED.
GCRYCTL_DISABLE_ALGO CHANGED: Not anymore thread-safe.
gcry_pk_genkey CHANGED: ECC curve params not returned.
gcry_md_hash_buffers NEW.
gcry_buffer_t NEW.
GCRYCTL_SET_ENFORCED_FIPS_FLAG NEW.
GCRYCTL_SET_PREFERRED_RNG_TYPE NEW.
GCRYCTL_GET_CURRENT_RNG_TYPE NEW.
GCRYCTL_CLOSE_RANDOM_DEVICE NEW.
GCRY_RNG_TYPE_STANDARD NEW.
GCRY_RNG_TYPE_FIPS NEW.
GCRY_RNG_TYPE_SYSTEM NEW.
gcry_mpi_is_neg NEW.
gcry_mpi_neg NEW.
gcry_mpi_abs NEW.
gcry_mpi_snatch NEW.
gcry_mpi_set_opaque_copy NEW.
gcry_mpi_point_t NEW.
gcry_mpi_point_new NEW.
gcry_mpi_point_release NEW.
gcry_mpi_point_get NEW.
gcry_mpi_point_snatch_get NEW.
gcry_mpi_point_set NEW.
gcry_mpi_point_snatch_set NEW.
gcry_ctx_t NEW.
gcry_ctx_release NEW.
gcry_mpi_ec_new NEW.
gcry_mpi_ec_get_mpi NEW.
gcry_mpi_ec_get_point NEW.
gcry_mpi_ec_set_mpi NEW.
gcry_mpi_ec_set_point NEW.
gcry_mpi_ec_get_affine NEW.
gcry_mpi_ec_dup NEW.
gcry_mpi_ec_add NEW.
gcry_mpi_ec_mul NEW.
gcry_mpi_ec_curve_point NEW.
GCRYMPI_FLAG_IMMUTABLE NEW.
GCRYMPI_FLAG_CONST NEW.
GCRYMPI_FLAG_USER1 NEW.
GCRYMPI_FLAG_USER2 NEW.
GCRYMPI_FLAG_USER3 NEW.
GCRYMPI_FLAG_USER4 NEW.
GCRYMPI_CONST_ONE NEW.
GCRYMPI_CONST_TWO NEW.
GCRYMPI_CONST_THREE NEW.
GCRYMPI_CONST_FOUR NEW.
GCRYMPI_CONST_EIGHT NEW.
GCRYMPI_FMT_OPAQUE NEW.
GCRYPT_VERSION_NUMBER NEW.
GCRY_KDF_SCRYPT NEW.
gcry_pubkey_get_sexp NEW.
GCRYCTL_DISABLE_LOCKED_SECMEM NEW.
GCRYCTL_DISABLE_PRIV_DROP NEW.
GCRY_CIPHER_SALSA20 NEW.
gcry_sexp_nth_buffer NEW.
gcry_sexp_extract_param NEW.
GCRY_CIPHER_SALSA20R12 NEW.
GCRY_CIPHER_GOST28147 NEW.
GCRY_MD_GOSTR3411_94 NEW.
GCRY_MD_STRIBOG256 NEW.
GCRY_MD_STRIBOG512 NEW.
GCRY_PK_ECC NEW.
gcry_log_debug NEW.
gcry_log_debughex NEW.
gcry_log_debugmpi NEW.
gcry_log_debugpnt NEW.
Noteworthy changes in version 1.5.0 (2011-06-29)
------------------------------------------------
* New function gcry_kdf_derive implementing OpenPGP S2K algorithms
and PBKDF2.
* Support for WindowsCE.
* Support for ECDH.
* Support for OAEP and PSS methods as described by RFC-3447.
* Fixed PKCS v1.5 code to always return the leading zero.
* New format specifiers "%M" and "%u" for gcry_sexp_build.
* Support opaque MPIs with "%m" and "%M" in gcry_sexp_build.
* New functions gcry_pk_get_curve and gcry_pk_get_param to map ECC
parameters to a curve name and to retrieve parameter values.
* gcry_mpi_cmp applied to opaque values has a defined semantic now.
* Uses the Intel AES-NI instructions if available.
* The use of the deprecated Alternative Public Key Interface
(gcry_ac_*) will now print compile time warnings.
* The module register subsystem has been deprecated. This subsystem
is not flexible enough and would always require ABI changes to
extend the internal interfaces. It will eventually be removed.
Please contact us on the gcrypt-devel mailing list to discuss
whether you really need this feature or how it can be replaced by
an internal plugin mechanism.
* CTR mode may now be used with data chunks of arbitrary length.
* Changes also done in 1.4.6 (2010-07-13):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* New variants of the TIGER algorithm.
* New cipher algorithm mode for AES-WRAP.
* Changes also done in 1.4.5 (2009-12-11):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Fixed minor memory leak in DSA key generation.
* No more switching to FIPS mode if /proc/version is not readable.
* Fixed sigill during Padlock detection on old CPUs.
* Fixed a hang on some W2000 machines.
* Boosted SHA-512 performance by 30% on ia32 boxes and gcc 4.3;
SHA-256 went up by 25%.
* Interface changes relative to the 1.4.6 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GCRY_PK_ECDH NEW.
gcry_pk_get_curve NEW.
gcry_pk_get_param NEW.
GCRYCTL_DISABLE_HWF NEW.
gcry_kdf_derive NEW.
gcry_pk_encrypt EXTENDED: Support OAEP.
gcry_pk_decrypt EXTENDED: Support OAEP.
gcry_pk_sign EXTENDED: Support PSS.
gcry_pk_verify EXTENDED: Support PSS.
gcry_sexp_build EXTENDED: Add format specifiers M and u.
* Interface changes relative to the 1.4.2 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GCRY_CIPHER_MODE_AESWRAP NEW.
GCRY_MD_TIGER1 NEW.
GCRY_MD_TIGER2 NEW.
Noteworthy changes in version 1.4.4 (2009-01-22)
------------------------------------------------
* Publish GCRY_MODULE_ID_USER and GCRY_MODULE_ID_USER_LAST constants.
This functionality has been in Libgcrypt since 1.3.0.
* MD5 may now be used in non-enforced fips mode.
* Fixed HMAC for SHA-384 and SHA-512 with keys longer than 64 bytes.
* In fips mode, RSA keys are now generated using the X9.31 algorithm
and DSA keys using the FIPS 186-2 algorithm.
* The transient-key flag is now also supported for DSA key
generation. DSA domain parameters may be given as well.
Noteworthy changes in version 1.4.3 (2008-09-18)
------------------------------------------------
* Try to auto-initialize Libgcrypt to minimize the effect of
applications not doing that correctly. This is not a perfect
solution but given that many applicationion would totally fail
without such a hack, we try to help at least with the most common
cases. Folks, please read the manual to learn how to properly
initialize Libgcrypt!
* Auto-initialize the secure memory to 32k instead of aborting the
process.
* Log fatal errors via syslog.
* Changed the name and the semantics of the fips mode config file.
* Add convenience macro gcry_fips_mode_active.
* More self-tests.
* Documentation cleanups.
Noteworthy changes in version 1.4.2 (2008-09-08)
------------------------------------------------
* The long missing gcry_mpi_lshift function has been added.
* RSA key generation now supports a "transient-key" flag.
* The keygrip computation for ECDSA has been implemented thus ECDSA
is now fully supported.
* A few macros have been replaced by functions for better type
checking.
* The thread initialization structure now carries version
information.
* The manual describes more clearly how to initialize Libgcrypt.
* The library may now be switched into a FIPS mode.
* Interface changes relative to the 1.3.0 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GCRYCTL_OPERATIONAL_P NEW.
GCRYCTL_FIPS_MODE_P NEW.
GCRYCTL_FORCE_FIPS_MODE NEW.
gcry_cipher_setkey NEW: Replaces macro.
gcry_cipher_setiv NEW: Replaces macro.
gcry_cipher_setctr NEW: Replaces macro.
gcry_mpi_lshift NEW.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Noteworthy changes in version 1.4.1 (2008-04-25)
------------------------------------------------
* Fixed a bug introduced by 1.3.1 which led to the comsumption of far
too much entropy for the intial seeding.
* Improved AES performance for CFB and CBC modes.
* Removed build problems for the Padlock support.
Noteworthy changes in version 1.4.0 (2007-12-10)
------------------------------------------------
* New configure option --disable-padlock-support which is mostly
useful in case of build problems.
Noteworthy changes in version 1.3.2 (2007-12-03)
------------------------------------------------
* The visibility attribute is now used if supported by the toolchain.
* The ACE engine of VIA processors is now used for AES-128.
* The ASN.1 DER template for SHA-224 has been fixed.
Noteworthy changes in version 1.3.1 (2007-10-26)
------------------------------------------------
* The entire library is now under the LGPL. The helper programs and
the manual are under the GPL. Kudos to Peter Gutmann for giving
permissions to relicense the rndw32 and rndunix modules.
* The Camellia cipher is now under the LGPL and included by default.
* Fixed a bug in the detection of symbol prefixes which inhibited the
build of optimzied assembler code on certain systems.
* Updated the entropy gatherer for W32.
Noteworthy changes in version 1.3.0 (2007-05-04)
------------------------------------------------
* Changed the way the RNG gets initialized. This allows to keep it
uninitialized as long as no random numbers are used. To override
this, the new macro gcry_fast_random_poll may be used. It is in
general a good idea to spread this macro into the application code
to make sure that these polls happen often enough.
* Made the RNG immune against fork without exec.
* Reading and writing the random seed file is now protected by a
fcntl style file lock on systems that provide this function.
* Support for SHA-224 and HMAC using SHA-384 and SHA-512.
* Support for the SEED cipher.
* Support for the Camellia cipher. Note that Camellia is disabled by
default, and that enabling it changes the license of libgcrypt from
LGPL to GPL.
* Support for OFB encryption mode.
* gcry_mpi_rshift does not anymore truncate the shift count.
* Reserved algorithm ranges for use by applications.
* Support for DSA2.
* The new function gcry_md_debug should be used instead of the
gcry_md_start_debug and gcry_md_stop_debug macros.
* New configure option --enable-random-daemon to support a system
wide random daemon. The daemon code is experimental and not yet
very well working. It will eventually allow to keep a global
random pool for the sake of short living processes.
* Non executable stack support is now used by default on systems
supporting it.
* Support for Microsoft Windows.
* Assembler support for the AMD64 architecture.
* New configure option --enable-mpi-path for optimized builds.
* Experimental support for ECDSA; should only be used for testing.
* New control code GCRYCTL_PRINT_CONFIG to print the build
configuration.
* Minor changes to some function declarations. Buffer arguments are
now typed as void pointer. This should not affect any compilation.
Fixed two bugs in return values and clarified documentation.
* Interface changes relative to the 1.2.0 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcry_fast_random_poll NEW
gcry_md_debug NEW
gcry_sexp_nth_string NEW
GCRY_MD_SHA224 NEW
GCRY_PK_USAGE_CERT NEW
GCRY_PK_USAGE_AUTH NEW
GCRY_PK_USAGE_UNKN NEW
GCRY_PK_ECDSA NEW
GCRY_CIPHER_SEED NEW
GCRY_CIPHER_CAMELLIA128 NEW
GCRY_CIPHER_CAMELLIA192 NEW
GCRY_CIPHER_CAMELLIA256 NEW
GCRYCTL_FAKED_RANDOM_P NEW
GCRYCTL_PRINT_CONFIG NEW
GCRYCTL_SET_RNDEGD_SOCKET NEW.
gcry_mpi_scan CHANGED: Argument BUFFER is now void*.
gcry_pk_algo_name CHANGED: Returns "?" instead of NULL.
gcry_cipher_algo_name CHANGED: Returns "?" instead of "".
gcry_pk_spec_t CHANGED: Element ALIASES is now const ptr.
gcry_md_write_t CHANGED: Argument BUF is now a const void*.
gcry_md_ctl CHANGED: Argument BUFFER is now void*.
gcry_cipher_encrypt CHANGED: Arguments IN and OUT are now void*.
gcry_cipher_decrypt CHANGED: Arguments IN and OUT are now void*.
gcry_sexp_sprint CHANGED: Argument BUFFER is now void*.
gcry_create_nonce CHANGED: Argument BUFFER is now void*.
gcry_randomize CHANGED: Argument BUFFER is now void*.
gcry_cipher_register CHANGED: Argument ALGORITHM_ID is now int*.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Noteworthy changes in version 1.2.0 (2004-04-15)
------------------------------------------------
* First stable release.
Noteworthy changes in version 1.1.94 (2004-03-29)
-------------------------------------------------
* The support for multi-threaded users goes into its third
incarnation. We removed compile time support for thread libraries.
To support the thread library of your choice, you have to set up
callback handlers at initialization time. New data structures, a
new control command, and default initializers are provided for this
purpose.
* Interface changes relative to the 1.1.93 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
libgcrypt-config --thread OBSOLETE
libgcrypt-pth.la REMOVED
libgcrypt-pthread.la REMOVED
GCRYCTL_SET_THREAD_CBS NEW
struct gcrypt_thread_cbs NEW
enum gcry_thread_option NEW
GCRY_THREAD_OPTION_PTH_IMPL NEW
GCRY_THREAD_OPTION_PTHREAD_IMPL NEW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Noteworthy changes in version 1.1.93 (2004-03-06)
-------------------------------------------------
* The automatic thread library detection has finally been removed.
From now on, only linking explicitely to libgcrypt, libgcrypt-pth
or libgcrypt-pthread is supported.
Noteworthy changes in version 1.1.92 (2004-02-20)
-------------------------------------------------
* Minor bug fixes.
* Included a limited implementation of RFC2268.
* Changed API of the gcry_ac_ functions. Only a very few programs
should be affected by this.
* Interface changes relative to the 1.1.91 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GCRY_CIPHER_RFC2268_40 NEW.
gcry_ac_data_set CHANGED: New argument FLAGS.
gcry_ac_data_get_name CHANGED: New argument FLAGS.
gcry_ac_data_get_index CHANGED: New argument FLAGS.
gcry_ac_key_pair_generate CHANGED: New and reordered arguments.
gcry_ac_key_test CHANGED: New argument HANDLE.
gcry_ac_key_get_nbits CHANGED: New argument HANDLE.
gcry_ac_key_get_grip CHANGED: New argument HANDLE.
gcry_ac_data_search REMOVED.
gcry_ac_data_add REMOVED.
GCRY_AC_DATA_FLAG_NO_BLINDING REMOVED.
GCRY_AC_FLAG_NO_BLINDING NEW: Replaces above.
Noteworthy changes in version 1.1.91 (2003-12-19)
-------------------------------------------------
* Code cleanups and minor bug fixes.
Noteworthy changes in version 1.1.90 (2003-11-14)
-------------------------------------------------
* The use of the GCRY_WEAK_RANDOM level is now deprecated in favor of
the new gcry_create_nonce function.
* gcry_sexp_build now supports a "%b" format to include a memory buffer.
* Minor configuration fixes.
* Interface changes relative to the 1.1.44 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcry_create_nonce NEW
gcry_sexp_build ENHANCED
Noteworthy changes in version 1.1.44 (2003-10-31)
-------------------------------------------------
* Bug fixes and more code cleanups.
* Enhanced the prime API.
* Interface changes relative to the 1.1.43 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcry_prime_group_generator NEW
gcry_prime_release_factors NEW
Noteworthy changes in version 1.1.43 (2003-09-04)
-------------------------------------------------
* Bug fixes and internal code cleanups.
* Support for the Serpent cipher algorithm.
* Interface changes relative to the 1.1.42 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcry_prime_generate NEW
gcry_prime_check NEW
Noteworthy changes in version 1.1.42 (2003-07-31)
-------------------------------------------------
* Major API cleanup. Applications need to be converted to the new
API. See README.apichanges for hints on how to do that. Backward
compatibility is provided where it was possible without too much
effort and did not collide with the overall sanitization effort.
However, this is only for ease of transition. NO DEPRECATED
FUNCTION OR DATA TYPE IS CONSIDERED A PART OF THE API OR ABI AND
WILL BE DROPPED IN THE FUTURE WITHOUT CHANGING THE SONAME OF THE
LIBRARY.
* If gcrypt.h is included in sources compiled by GCC 3.1 or later,
deprecated attributes will warn about use of obsolete functions and
type definitions. You can suppress these warnings by passing
-Wno-deprecated-declarations to the gcc command.
* gcry_check_version must be called from now on to initialize the
library, it is not longer optional.
* Removed `libgcrypt errno' concept.
* Libgcrypt depends on libgpg-error, a library that provides error
codes and according functions for all GnuPG components. Functions
that used to return error codes asa `int' have been changed to
return a code of type `gcry_error_t'. All GCRYERR_* error symbols
have been removed, since they are now contained in libgpg-error
(GPG_ERR_*). All functions and types in libgpg-error have also been
wrapped in Libgcrypt. The new types are gcry_err_code_t and
gcry_err_source_t. The new functions are gcry_err_code,
gcry_err_source, gcry_error, gcry_err_make, gcry_error_from_errno,
gcry_err_make_from_errno, gcry_err_code_from_errno,
gcry_err_code_to_errno, gcry_strsource.
* New function gcry_mpi_dump to help in debugging.
* Added alternative interface for asymmetric cryptography.
* CRC-32, CRC-32 a'la RFC 1510, CRC-24 a'la RFC 2440 are now
supported.
* SHA-256, SHA-384 and SHA-512 are now supported.
* 128 bit Twofish is now supported.
* The random module won't print the "not enough random bytes
available" anymore. A new progress status is issued instead.
* CBC-MAC for block ciphers is now supported, by using a
GCRY_CIPHER_CBC_MAC cipher flag.
* CTR mode for block ciphers is now supported.
* The public RSA exponent can now be specified in key generation.
* RSA blinding is now supported and is used automatically for RSA
decryption. It can be explicitely disabled by using the
`no-blinding' symbol in the `flags' S-Expression or by using the
GCRY_AC_FLAG_DATA_NO_BLINDING flag when using the ac interface.
* gcry_sexp_canon_len does not use a `historically encoded' error
code anymore.
* Interface changes relative to the 1.1.12 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GCRY_MPI DEPRECATED; Use: gcry_mpi_t
GcryMPI DEPRECATED; Use: gcry_mpi_t
GCRY_SEXP DEPRECATED; Use: gcry_sexp_t
GcrySexp DEPRECATED; Use: gcry_sexp_t
GCRY_CIPHER_HD DEPRECATED; Use: gcry_cipher_hd_t
GcryCipherHd DEPRECATED; Use: gcry_cipher_hd_t
GCRY_MD_HD DEPRECATED; Use: gcry_md_hd_t
GcryMDHd DEPRECATED; Use: gcry_md_hd_t
gcry_error_t NEW
gcry_err_code_t NEW
gcry_err_source_t NEW
gcry_err_make NEW
gcry_error NEW
gcry_err_code NEW
gcry_err_source NEW
gcry_err_code_from_errno NEW
gcry_err_code_to_errno NEW
gcry_err_make_from_errno NEW
gcry_error_from_errno NEW
gcry_strsource NEW
GCRYERR_{some error code} REMOVED; Use GPG_ERR_*
from libgpg-error instead.
gcry_errno REMOVED
gcry_sexp_canon_len CHANGED
gcry_sexp_build_array NEW
gcry_mpi_scan CHANGED: New argument to separate in/out args.
gcry_mpi_print CHANGED: Ditto.
gcry_mpi_dump NEW
gcry_cipher_open CHANGED
gcry_cipher_reset NEW
gcry_cipher_register NEW
gcry_cipher_unregister NEW
gcry_cipher_list NEW
gcry_cipher_algo_keylen REPLACED macro with function.
gcry_cipher_algo_blklen REPLACED macro with function.
gcry_pk_register NEW
gcry_pk_unregister NEW
gcry_pk_list NEW
gcry_pk_decrypt ENHANCED: Allows flag to return
complete S-expression.
gcry_md_open CHANGED
gcry_md_copy CHANGED
gcry_md_is_enabled NEW
gcry_md_is_secure NEW
gcry_md_register NEW
gcry_md_unregister NEW
gcry_md_list NEW
gcry_ac_data_t NEW
gcry_ac_key_t NEW
gcry_ac_key_pair_t NEW
gcry_ac_handle_t NEW
gcry_ac_key_spec_rsa_t NEW
gcry_ac_data_new NEW
gcry_ac_data_destroy NEW
gcry_ac_data_set NEW
gcry_ac_data_copy NEW
gcry_ac_data_length NEW
gcry_ac_data_get_name NEW
gcry_ac_data_get_index NEW
gcry_ac_data_clear NEW
gcry_ac_open NEW
gcry_ac_close NEW
gcry_ac_key_init NEW
gcry_ac_key_pair_generate NEW
gcry_ac_key_pair_extract NEW
gcry_ac_key_data_get NEW
gcry_ac_key_test NEW
gcry_ac_key_get_nbits NEW
gcry_ac_key_get_grip NEW
gcry_ac_key_destroy NEW
gcry_ac_key_pair_destroy NEW
gcry_ac_data_encrypt NEW
gcry_ac_data_decrypt NEW
gcry_ac_data_sign NEW
gcry_ac_data_verify NEW
gcry_ac_id_to_name NEW
gcry_ac_name_to_id NEW
gcry_handler_progress_t NEW
gcry_handler_alloc_t NEW
gcry_handler_secure_check_t NEW
gcry_handle_realloc_t NEW
gcry_handler_free_t NEW
gcry_handler_no_mem_t NEW
gcry_handler_error_t NEW
gcry_handler_log_t NEW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Noteworthy changes in version 1.1.12 (2003-01-20)
-------------------------------------------------
* gcry_pk_sign, gcry_pk_verify and gcry_pk_encrypt can now handle an
optional pkcs1 flags parameter in the S-expression. A similar flag
may be passed to gcry_pk_decrypt but it is only syntactically
implemented.
* New convenience macro gcry_md_get_asnoid.
* There is now some real stuff in the manual.
Noteworthy changes in version 1.1.11 (2002-12-21)
-------------------------------------------------
* Don't export internal symbols anymore (currently only for GNU systems)
* New algorithm: MD4
* Implemented ciphertext stealing.
* Smaller bugs fixes and a few new OIDs.
* Interface changes relative to the 1.1.8 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcry_cipher_cts NEW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Noteworthy changes in version 1.1.10 (2002-09-20)
-------------------------------------------------
* Fixed shared library builds for i386, PPC and Sparc.
* Added simple benchmark tool.
* Replaced the internal mutexes by code which automatically adapts to
the used threading library. Currently Pth and Pthread are
supported. For non-ELF systems the GNU toolchain is now required..
* Added untested support to build Windows DLLs.
Noteworthy changes in version 1.1.9 (2002-08-23)
------------------------------------------------
* Support for plain old DES.
Noteworthy changes in version 1.1.8 (2002-06-25)
------------------------------------------------
* Minor cleanups and exported a few new functions.
* Interface changes relative to the 1.1.7 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gcry_mpi_div NEW
gcry_mpi_mod NEW
gcry_mpi_invm NEW
gcry_mpi_swap NEW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Noteworthy changes in version 1.1.7 (2002-05-21)
------------------------------------------------
* Libgcrypt is now distributed under the terms of the GNU Lesser
General Public License; see the README file for details.
* It is possible to use libgcrypt w/o intialized secure memory.
* Libgcrypt should now be thread safe after the initialization.
gcry_control (GCRYCRL_INITIALIZATION_FINISHED,NULL,0) should have
been called before creating additional threads.
* Interface changes relative to the 1.1.6 release:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GCRYCTL_DISABLE_INTERNAL_LOCKING NEW
GCRYCTL_DISABLE_SECMEM NEW
GCRYCTL_INITIALIZATION_FINISHED NEW
GCRYCTL_INITIALIZATION_FINISHED_P NEW
GCRYCTL_ANY_INITIALIZATION_P NEW
gcry_strdup NEW
gcry_sexp_create NEW
gcry_sexp_new NEW
gcry_set_progress_handler NEW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Noteworthy changes in version 1.1.6 (2002-02-07)
------------------------------------------------
* Enhanced the S-expression conversion functions.
Noteworthy changes in version 1.1.5 (2001-12-18)
------------------------------------------------
* gcry_{cipher,md}_map_name are now able to map stringified object IDs.
* New functions gcry_sexp_canon_len and gcry_cipher_mode_from_oid.
* Closed some memory leaks.
Noteworthy changes in version 1.1.4 (2001-08-03)
------------------------------------------------
* Arcfour does now work.
* Some minor fixes.
* Added a first test program
* Migrated to autoconf 2.52.
Noteworthy changes in version 1.1.3 (2001-05-31)
------------------------------------------------
* First release of Libgcrypt which is a result of splitting GnuPG
into into libgcrypt and GnuPG.
Copyright 2001, 2002, 2003, 2004, 2007, 2008,
2009, 2011 Free Software Foundation, Inc.
Copyright 2013 g10 Code GmbH
This file is free software; as a special exception the author gives
unlimited permission to copy and/or distribute it, with or without
modifications, as long as this notice is preserved.
This file is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY, to the extent permitted by law; without even the
implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
diff --git a/doc/gcrypt.texi b/doc/gcrypt.texi
index dd244691..78315052 100644
--- a/doc/gcrypt.texi
+++ b/doc/gcrypt.texi
@@ -1,6705 +1,6716 @@
\input texinfo @c -*- Texinfo -*-
@c %**start of header
@setfilename gcrypt.info
@include version.texi
@settitle The Libgcrypt Reference Manual
@c Unify some of the indices.
@syncodeindex tp fn
@syncodeindex pg fn
@c %**end of header
@copying
This manual is for Libgcrypt
(version @value{VERSION}, @value{UPDATED}),
which is GNU's library of cryptographic building blocks.
@noindent
Copyright @copyright{} 2000, 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2011, 2012 Free Software Foundation, Inc. @*
Copyright @copyright{} 2012, 2013, 2016, 2017 g10 Code GmbH
@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version. The text of the license can be found in the
section entitled ``GNU General Public License''.
@end quotation
@end copying
@dircategory GNU Libraries
@direntry
* libgcrypt: (gcrypt). Cryptographic function library.
@end direntry
@c A couple of macros with no effect on texinfo
@c but used by the yat2m processor.
@macro manpage {a}
@end macro
@macro mansect {a}
@end macro
@macro manpause
@end macro
@macro mancont
@end macro
@c
@c Printing stuff taken from gcc.
@c
@macro gnupgtabopt{body}
@code{\body\}
@end macro
@c
@c Titlepage
@c
@setchapternewpage odd
@titlepage
@title The Libgcrypt Reference Manual
@subtitle Version @value{VERSION}
@subtitle @value{UPDATED}
@author Werner Koch (@email{wk@@gnupg.org})
@author Moritz Schulte (@email{mo@@g10code.com})
@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage
@ifnothtml
@summarycontents
@contents
@page
@end ifnothtml
@ifnottex
@node Top
@top The Libgcrypt Library
@insertcopying
@end ifnottex
@menu
* Introduction:: What is Libgcrypt.
* Preparation:: What you should do before using the library.
* Generalities:: General library functions and data types.
* Handler Functions:: Working with handler functions.
* Symmetric cryptography:: How to use symmetric cryptography.
* Public Key cryptography:: How to use public key cryptography.
* Hashing:: How to use hash algorithms.
* Message Authentication Codes:: How to use MAC algorithms.
* Key Derivation:: How to derive keys from strings
* Random Numbers:: How to work with random numbers.
* S-expressions:: How to manage S-expressions.
* MPI library:: How to work with multi-precision-integers.
* Prime numbers:: How to use the Prime number related functions.
* Utilities:: Utility functions.
* Tools:: Utility tools.
* Configuration:: Configuration files and environment variables.
* Architecture:: How Libgcrypt works internally.
Appendices
* Self-Tests:: Description of the self-tests.
* FIPS Mode:: Description of the FIPS mode.
* Library Copying:: The GNU Lesser General Public License
says how you can copy and share Libgcrypt.
* Copying:: The GNU General Public License says how you
can copy and share some parts of Libgcrypt.
Indices
* Figures and Tables:: Index of figures and tables.
* Concept Index:: Index of concepts and programs.
* Function and Data Index:: Index of functions, variables and data types.
@end menu
@ifhtml
@page
@summarycontents
@contents
@end ifhtml
@c **********************************************************
@c ******************* Introduction ***********************
@c **********************************************************
@node Introduction
@chapter Introduction
Libgcrypt is a library providing cryptographic building blocks.
@menu
* Getting Started:: How to use this manual.
* Features:: A glance at Libgcrypt's features.
* Overview:: Overview about the library.
@end menu
@node Getting Started
@section Getting Started
This manual documents the Libgcrypt library application programming
interface (API). All functions and data types provided by the library
are explained.
@noindent
The reader is assumed to possess basic knowledge about applied
cryptography.
This manual can be used in several ways. If read from the beginning
to the end, it gives a good introduction into the library and how it
can be used in an application. Forward references are included where
necessary. Later on, the manual can be used as a reference manual to
get just the information needed about any particular interface of the
library. Experienced programmers might want to start looking at the
examples at the end of the manual, and then only read up those parts
of the interface which are unclear.
@node Features
@section Features
Libgcrypt might have a couple of advantages over other libraries doing
a similar job.
@table @asis
@item It's Free Software
Anybody can use, modify, and redistribute it under the terms of the GNU
Lesser General Public License (@pxref{Library Copying}). Note, that
some parts (which are in general not needed by applications) are subject
to the terms of the GNU General Public License (@pxref{Copying}); please
see the README file of the distribution for of list of these parts.
@item It encapsulates the low level cryptography
Libgcrypt provides a high level interface to cryptographic
building blocks using an extensible and flexible API.
@end table
@node Overview
@section Overview
@noindent
The Libgcrypt library is fully thread-safe, where it makes
sense to be thread-safe. Not thread-safe are some cryptographic
functions that modify a certain context stored in handles. If the
user really intents to use such functions from different threads on
the same handle, he has to take care of the serialization of such
functions himself. If not described otherwise, every function is
thread-safe.
Libgcrypt depends on the library `libgpg-error', which contains some
common code used by other GnuPG components.
@c **********************************************************
@c ******************* Preparation ************************
@c **********************************************************
@node Preparation
@chapter Preparation
To use Libgcrypt, you have to perform some changes to your
sources and the build system. The necessary changes are small and
explained in the following sections. At the end of this chapter, it
is described how the library is initialized, and how the requirements
of the library are verified.
@menu
* Header:: What header file you need to include.
* Building sources:: How to build sources using the library.
* Building sources using Automake:: How to build sources with the help of Automake.
* Initializing the library:: How to initialize the library.
* Multi-Threading:: How Libgcrypt can be used in a MT environment.
* Enabling FIPS mode:: How to enable the FIPS mode.
* Hardware features:: How to disable hardware features.
@end menu
@node Header
@section Header
All interfaces (data types and functions) of the library are defined
in the header file @file{gcrypt.h}. You must include this in all source
files using the library, either directly or through some other header
file, like this:
@example
#include <gcrypt.h>
@end example
The name space of Libgcrypt is @code{gcry_*} for function
and type names and @code{GCRY*} for other symbols. In addition the
same name prefixes with one prepended underscore are reserved for
internal use and should never be used by an application. Note that
Libgcrypt uses libgpg-error, which uses @code{gpg_*} as
name space for function and type names and @code{GPG_*} for other
symbols, including all the error codes.
@noindent
Certain parts of gcrypt.h may be excluded by defining these macros:
@table @code
@item GCRYPT_NO_MPI_MACROS
Do not define the shorthand macros @code{mpi_*} for @code{gcry_mpi_*}.
@item GCRYPT_NO_DEPRECATED
Do not include definitions for deprecated features. This is useful to
make sure that no deprecated features are used.
@end table
@node Building sources
@section Building sources
If you want to compile a source file including the `gcrypt.h' header
file, you must make sure that the compiler can find it in the
directory hierarchy. This is accomplished by adding the path to the
directory in which the header file is located to the compilers include
file search path (via the @option{-I} option).
However, the path to the include file is determined at the time the
source is configured. To solve this problem, Libgcrypt ships with a small
helper program @command{libgcrypt-config} that knows the path to the
include file and other configuration options. The options that need
to be added to the compiler invocation at compile time are output by
the @option{--cflags} option to @command{libgcrypt-config}. The following
example shows how it can be used at the command line:
@example
gcc -c foo.c `libgcrypt-config --cflags`
@end example
Adding the output of @samp{libgcrypt-config --cflags} to the
compiler’s command line will ensure that the compiler can find the
Libgcrypt header file.
A similar problem occurs when linking the program with the library.
Again, the compiler has to find the library files. For this to work,
the path to the library files has to be added to the library search path
(via the @option{-L} option). For this, the option @option{--libs} to
@command{libgcrypt-config} can be used. For convenience, this option
also outputs all other options that are required to link the program
with the Libgcrypt libraries (in particular, the @samp{-lgcrypt}
option). The example shows how to link @file{foo.o} with the Libgcrypt
library to a program @command{foo}.
@example
gcc -o foo foo.o `libgcrypt-config --libs`
@end example
Of course you can also combine both examples to a single command by
specifying both options to @command{libgcrypt-config}:
@example
gcc -o foo foo.c `libgcrypt-config --cflags --libs`
@end example
@node Building sources using Automake
@section Building sources using Automake
It is much easier if you use GNU Automake instead of writing your own
Makefiles. If you do that, you do not have to worry about finding and
invoking the @command{libgcrypt-config} script at all.
Libgcrypt provides an extension to Automake that does all
the work for you.
@c A simple macro for optional variables.
@macro ovar{varname}
@r{[}@var{\varname\}@r{]}
@end macro
@defmac AM_PATH_LIBGCRYPT (@ovar{minimum-version}, @ovar{action-if-found}, @ovar{action-if-not-found})
Check whether Libgcrypt (at least version
@var{minimum-version}, if given) exists on the host system. If it is
found, execute @var{action-if-found}, otherwise do
@var{action-if-not-found}, if given.
Additionally, the function defines @code{LIBGCRYPT_CFLAGS} to the
flags needed for compilation of the program to find the
@file{gcrypt.h} header file, and @code{LIBGCRYPT_LIBS} to the linker
flags needed to link the program to the Libgcrypt library. If the
used helper script does not match the target type you are building for
a warning is printed and the string @code{libgcrypt} is appended to the
variable @code{gpg_config_script_warn}.
This macro searches for @command{libgcrypt-config} along the PATH. If
you are cross-compiling, it is useful to set the environment variable
@code{SYSROOT} to the top directory of your target. The macro will
then first look for the helper program in the @file{bin} directory
below that top directory. An absolute directory name must be used for
@code{SYSROOT}. Finally, if the configure command line option
@code{--with-libgcrypt-prefix} is used, only its value is used for the top
directory below which the helper script is expected.
@end defmac
You can use the defined Autoconf variables like this in your
@file{Makefile.am}:
@example
AM_CPPFLAGS = $(LIBGCRYPT_CFLAGS)
LDADD = $(LIBGCRYPT_LIBS)
@end example
@node Initializing the library
@section Initializing the library
Before the library can be used, it must initialize itself. This is
achieved by invoking the function @code{gcry_check_version} described
below.
Also, it is often desirable to check that the version of
Libgcrypt used is indeed one which fits all requirements.
Even with binary compatibility, new features may have been introduced,
but due to problem with the dynamic linker an old version may actually
be used. So you may want to check that the version is okay right
after program startup.
@deftypefun {const char *} gcry_check_version (const char *@var{req_version})
The function @code{gcry_check_version} initializes some subsystems used
by Libgcrypt and must be invoked before any other function in the
library.
@xref{Multi-Threading}.
Furthermore, this function returns the version number of the library.
It can also verify that the version number is higher than a certain
required version number @var{req_version}, if this value is not a null
pointer.
@end deftypefun
Libgcrypt uses a concept known as secure memory, which is a region of
memory set aside for storing sensitive data. Because such memory is a
scarce resource, it needs to be setup in advanced to a fixed size.
Further, most operating systems have special requirements on how that
secure memory can be used. For example, it might be required to install
an application as ``setuid(root)'' to allow allocating such memory.
Libgcrypt requires a sequence of initialization steps to make sure that
this works correctly. The following examples show the necessary steps.
If you don't have a need for secure memory, for example if your
application does not use secret keys or other confidential data or it
runs in a controlled environment where key material floating around in
memory is not a problem, you should initialize Libgcrypt this way:
@example
/* Version check should be the very first call because it
makes sure that important subsystems are initialized. */
if (!gcry_check_version (GCRYPT_VERSION))
@{
fputs ("libgcrypt version mismatch\n", stderr);
exit (2);
@}
/* Disable secure memory. */
gcry_control (GCRYCTL_DISABLE_SECMEM, 0);
/* ... If required, other initialization goes here. */
/* Tell Libgcrypt that initialization has completed. */
gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
@end example
If you have to protect your keys or other information in memory against
being swapped out to disk and to enable an automatic overwrite of used
and freed memory, you need to initialize Libgcrypt this way:
@example
/* Version check should be the very first call because it
makes sure that important subsystems are initialized. */
if (!gcry_check_version (GCRYPT_VERSION))
@{
fputs ("libgcrypt version mismatch\n", stderr);
exit (2);
@}
@anchor{sample-use-suspend-secmem}
/* We don't want to see any warnings, e.g. because we have not yet
parsed program options which might be used to suppress such
warnings. */
gcry_control (GCRYCTL_SUSPEND_SECMEM_WARN);
/* ... If required, other initialization goes here. Note that the
process might still be running with increased privileges and that
the secure memory has not been initialized. */
/* Allocate a pool of 16k secure memory. This makes the secure memory
available and also drops privileges where needed. Note that by
using functions like gcry_xmalloc_secure and gcry_mpi_snew Libgcrypt
- may extend the secure memory pool with memory which lacks the
+ may expand the secure memory pool with memory which lacks the
property of not being swapped out to disk. */
gcry_control (GCRYCTL_INIT_SECMEM, 16384, 0);
@anchor{sample-use-resume-secmem}
/* It is now okay to let Libgcrypt complain when there was/is
a problem with the secure memory. */
gcry_control (GCRYCTL_RESUME_SECMEM_WARN);
/* ... If required, other initialization goes here. */
/* Tell Libgcrypt that initialization has completed. */
gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
@end example
It is important that these initialization steps are not done by a
library but by the actual application. A library using Libgcrypt might
want to check for finished initialization using:
@example
if (!gcry_control (GCRYCTL_INITIALIZATION_FINISHED_P))
@{
fputs ("libgcrypt has not been initialized\n", stderr);
abort ();
@}
@end example
Instead of terminating the process, the library may instead print a
warning and try to initialize Libgcrypt itself. See also the section on
multi-threading below for more pitfalls.
@node Multi-Threading
@section Multi-Threading
As mentioned earlier, the Libgcrypt library is
thread-safe if you adhere to the following requirements:
@itemize @bullet
@item
If you use pthread and your applications forks and does not directly
call exec (even calling stdio functions), all kind of problems may
occur. Future versions of Libgcrypt will try to cleanup using
pthread_atfork but even that may lead to problems. This is a common
problem with almost all applications using pthread and fork.
@item
The function @code{gcry_check_version} must be called before any other
function in the library. To
achieve this in multi-threaded programs, you must synchronize the
memory with respect to other threads that also want to use
Libgcrypt. For this, it is sufficient to call
@code{gcry_check_version} before creating the other threads using
Libgcrypt@footnote{At least this is true for POSIX threads,
as @code{pthread_create} is a function that synchronizes memory with
respects to other threads. There are many functions which have this
property, a complete list can be found in POSIX, IEEE Std 1003.1-2003,
Base Definitions, Issue 6, in the definition of the term ``Memory
Synchronization''. For other thread packages, more relaxed or more
strict rules may apply.}.
@item
Just like the function @code{gpg_strerror}, the function
@code{gcry_strerror} is not thread safe. You have to use
@code{gpg_strerror_r} instead.
@end itemize
@node Enabling FIPS mode
@section How to enable the FIPS mode
@cindex FIPS mode
@cindex FIPS 140
@anchor{enabling fips mode}
Libgcrypt may be used in a FIPS 140-2 mode. Note, that this does not
necessary mean that Libcgrypt is an appoved FIPS 140-2 module. Check the
NIST database at @url{http://csrc.nist.gov/groups/STM/cmvp/} to see what
versions of Libgcrypt are approved.
Because FIPS 140 has certain restrictions on the use of cryptography
which are not always wanted, Libgcrypt needs to be put into FIPS mode
explicitly. Three alternative mechanisms are provided to switch
Libgcrypt into this mode:
@itemize
@item
If the file @file{/proc/sys/crypto/fips_enabled} exists and contains a
numeric value other than @code{0}, Libgcrypt is put into FIPS mode at
initialization time. Obviously this works only on systems with a
@code{proc} file system (i.e. GNU/Linux).
@item
If the file @file{/etc/gcrypt/fips_enabled} exists, Libgcrypt is put
into FIPS mode at initialization time. Note that this filename is
hardwired and does not depend on any configuration options.
@item
If the application requests FIPS mode using the control command
@code{GCRYCTL_FORCE_FIPS_MODE}. This must be done prior to any
initialization (i.e. before @code{gcry_check_version}).
@end itemize
@cindex Enforced FIPS mode
In addition to the standard FIPS mode, Libgcrypt may also be put into
an Enforced FIPS mode by writing a non-zero value into the file
@file{/etc/gcrypt/fips_enabled} or by using the control command
@code{GCRYCTL_SET_ENFORCED_FIPS_FLAG} before any other calls to
libgcrypt. The Enforced FIPS mode helps to detect applications
which don't fulfill all requirements for using
Libgcrypt in FIPS mode (@pxref{FIPS Mode}).
Once Libgcrypt has been put into FIPS mode, it is not possible to
switch back to standard mode without terminating the process first.
If the logging verbosity level of Libgcrypt has been set to at least
2, the state transitions and the self-tests are logged.
@node Hardware features
@section How to disable hardware features
@cindex hardware features
@anchor{hardware features}
Libgcrypt makes use of certain hardware features. If the use of a
feature is not desired it may be either be disabled by a program or
globally using a configuration file. The currently supported features
are
@table @code
@item padlock-rng
@item padlock-aes
@item padlock-sha
@item padlock-mmul
@item intel-cpu
@item intel-fast-shld
@item intel-bmi2
@item intel-ssse3
@item intel-pclmul
@item intel-aesni
@item intel-rdrand
@item intel-avx
@item intel-avx2
@item intel-rdtsc
@item arm-neon
@end table
To disable a feature for all processes using Libgcrypt 1.6 or newer,
create the file @file{/etc/gcrypt/hwf.deny} and put each feature not
to be used on a single line. Empty lines, white space, and lines
prefixed with a hash mark are ignored. The file should be world
readable.
To disable a feature specifically for a program that program must tell
it Libgcrypt before before calling @code{gcry_check_version}.
Example:@footnote{NB. Libgcrypt uses the RDRAND feature only as one
source of entropy. A CPU with a broken RDRAND will thus not
compromise of the random number generator}
@example
gcry_control (GCRYCTL_DISABLE_HWF, "intel-rdrand", NULL);
@end example
@noindent
To print the list of active features you may use this command:
@example
mpicalc --print-config | grep ^hwflist: | tr : '\n' | tail -n +2
@end example
@c **********************************************************
@c ******************* General ****************************
@c **********************************************************
@node Generalities
@chapter Generalities
@menu
* Controlling the library:: Controlling Libgcrypt's behavior.
* Error Handling:: Error codes and such.
@end menu
@node Controlling the library
@section Controlling the library
@deftypefun gcry_error_t gcry_control (enum gcry_ctl_cmds @var{cmd}, ...)
This function can be used to influence the general behavior of
Libgcrypt in several ways. Depending on @var{cmd}, more
arguments can or have to be provided.
@table @code
@item GCRYCTL_ENABLE_M_GUARD; Arguments: none
This command enables the built-in memory guard. It must not be used
to activate the memory guard after the memory management has already
been used; therefore it can ONLY be used before
@code{gcry_check_version}. Note that the memory guard is NOT used
when the user of the library has set his own memory management
callbacks.
@item GCRYCTL_ENABLE_QUICK_RANDOM; Arguments: none
This command inhibits the use the very secure random quality level
(@code{GCRY_VERY_STRONG_RANDOM}) and degrades all request down to
@code{GCRY_STRONG_RANDOM}. In general this is not recommended. However,
for some applications the extra quality random Libgcrypt tries to create
is not justified and this option may help to get better performance.
Please check with a crypto expert whether this option can be used for
your application.
This option can only be used at initialization time.
@item GCRYCTL_DUMP_RANDOM_STATS; Arguments: none
This command dumps random number generator related statistics to the
library's logging stream.
@item GCRYCTL_DUMP_MEMORY_STATS; Arguments: none
This command dumps memory management related statistics to the library's
logging stream.
@item GCRYCTL_DUMP_SECMEM_STATS; Arguments: none
This command dumps secure memory management related statistics to the
library's logging stream.
@item GCRYCTL_DROP_PRIVS; Arguments: none
This command disables the use of secure memory and drops the privileges
of the current process. This command has not much use; the suggested way
to disable secure memory is to use @code{GCRYCTL_DISABLE_SECMEM} right
after initialization.
@item GCRYCTL_DISABLE_SECMEM; Arguments: none
This command disables the use of secure memory. If this command is
used in FIPS mode, FIPS mode will be disabled and the function
@code{gcry_fips_mode_active} returns false. However, in Enforced FIPS
mode this command has no effect at all.
Many applications do not require secure memory, so they should disable
it right away. This command should be executed right after
@code{gcry_check_version}.
@item GCRYCTL_DISABLE_LOCKED_SECMEM; Arguments: none
This command disables the use of the mlock call for secure memory.
Disabling the use of mlock may for example be done if an encrypted
swap space is in use. This command should be executed right after
@code{gcry_check_version}. Note that by using functions like
-gcry_xmalloc_secure and gcry_mpi_snew Libgcrypt may extend the secure
+gcry_xmalloc_secure and gcry_mpi_snew Libgcrypt may expand the secure
memory pool with memory which lacks the property of not being swapped
out to disk (but will still be zeroed out on free).
@item GCRYCTL_DISABLE_PRIV_DROP; Arguments: none
This command sets a global flag to tell the secure memory subsystem
that it shall not drop privileges after secure memory has been
allocated. This command is commonly used right after
@code{gcry_check_version} but may also be used right away at program
startup. It won't have an effect after the secure memory pool has
been initialized. WARNING: A process running setuid(root) is a severe
security risk. Processes making use of Libgcrypt or other complex
code should drop these extra privileges as soon as possible. If this
command has been used the caller is responsible for dropping the
privileges.
-@item GCRYCTL_INIT_SECMEM; Arguments: int nbytes
+@item GCRYCTL_INIT_SECMEM; Arguments: unsigned int nbytes
This command is used to allocate a pool of secure memory and thus
enabling the use of secure memory. It also drops all extra privileges
the process has (i.e. if it is run as setuid (root)). If the argument
@var{nbytes} is 0, secure memory will be disabled. The minimum amount
of secure memory allocated is currently 16384 bytes; you may thus use a
value of 1 to request that default size.
+@item GCRYCTL_AUTO_EXPAND_SECMEM; Arguments: unsigned int chunksize
+This command enables on-the-fly expanding of the secure memory area.
+Note that by using functions like @code{gcry_xmalloc_secure} and
+@code{gcry_mpi_snew} will do this auto expanding anyway. The argument
+to this option is the suggested size for new secure memory areas. A
+larger size improves performance of all memory allocation and
+releasing functions. The given chunksize is rounded up to the next
+32KiB. The drawback of auto expanding is that memory might be swapped
+out to disk; this can be fixed by configuring the system to use an
+encrypted swap space.
+
@item GCRYCTL_TERM_SECMEM; Arguments: none
This command zeroises the secure memory and destroys the handler. The
secure memory pool may not be used anymore after running this command.
If the secure memory pool as already been destroyed, this command has
no effect. Applications might want to run this command from their
exit handler to make sure that the secure memory gets properly
destroyed. This command is not necessarily thread-safe but that
should not be needed in cleanup code. It may be called from a signal
handler.
@item GCRYCTL_DISABLE_SECMEM_WARN; Arguments: none
Disable warning messages about problems with the secure memory
subsystem. This command should be run right after
@code{gcry_check_version}.
@item GCRYCTL_SUSPEND_SECMEM_WARN; Arguments: none
Postpone warning messages from the secure memory subsystem.
@xref{sample-use-suspend-secmem,,the initialization example}, on how to
use it.
@item GCRYCTL_RESUME_SECMEM_WARN; Arguments: none
Resume warning messages from the secure memory subsystem.
@xref{sample-use-resume-secmem,,the initialization example}, on how to
use it.
@item GCRYCTL_USE_SECURE_RNDPOOL; Arguments: none
This command tells the PRNG to store random numbers in secure memory.
This command should be run right after @code{gcry_check_version} and not
later than the command GCRYCTL_INIT_SECMEM. Note that in FIPS mode the
secure memory is always used.
@item GCRYCTL_SET_RANDOM_SEED_FILE; Arguments: const char *filename
This command specifies the file, which is to be used as seed file for
the PRNG. If the seed file is registered prior to initialization of the
PRNG, the seed file's content (if it exists and seems to be valid) is
fed into the PRNG pool. After the seed file has been registered, the
PRNG can be signalled to write out the PRNG pool's content into the seed
file with the following command.
@item GCRYCTL_UPDATE_RANDOM_SEED_FILE; Arguments: none
Write out the PRNG pool's content into the registered seed file.
Multiple instances of the applications sharing the same random seed file
can be started in parallel, in which case they will read out the same
pool and then race for updating it (the last update overwrites earlier
updates). They will differentiate only by the weak entropy that is
added in read_seed_file based on the PID and clock, and up to 16 bytes
of weak random non-blockingly. The consequence is that the output of
these different instances is correlated to some extent. In a perfect
attack scenario, the attacker can control (or at least guess) the PID
and clock of the application, and drain the system's entropy pool to
reduce the "up to 16 bytes" above to 0. Then the dependencies of the
initial states of the pools are completely known. Note that this is not
an issue if random of @code{GCRY_VERY_STRONG_RANDOM} quality is
requested as in this case enough extra entropy gets mixed. It is also
not an issue when using Linux (rndlinux driver), because this one
guarantees to read full 16 bytes from /dev/urandom and thus there is no
way for an attacker without kernel access to control these 16 bytes.
@item GCRYCTL_CLOSE_RANDOM_DEVICE; Arguments: none
Try to close the random device. If on Unix system you call fork(),
the child process does no call exec(), and you do not intend to use
Libgcrypt in the child, it might be useful to use this control code to
close the inherited file descriptors of the random device. If
Libgcrypt is later used again by the child, the device will be
re-opened. On non-Unix systems this control code is ignored.
@item GCRYCTL_SET_VERBOSITY; Arguments: int level
This command sets the verbosity of the logging. A level of 0 disables
all extra logging whereas positive numbers enable more verbose logging.
The level may be changed at any time but be aware that no memory
synchronization is done so the effect of this command might not
immediately show up in other threads. This command may even be used
prior to @code{gcry_check_version}.
@item GCRYCTL_SET_DEBUG_FLAGS; Arguments: unsigned int flags
Set the debug flag bits as given by the argument. Be aware that that no
memory synchronization is done so the effect of this command might not
immediately show up in other threads. The debug flags are not
considered part of the API and thus may change without notice. As of
now bit 0 enables debugging of cipher functions and bit 1 debugging of
multi-precision-integers. This command may even be used prior to
@code{gcry_check_version}.
@item GCRYCTL_CLEAR_DEBUG_FLAGS; Arguments: unsigned int flags
Set the debug flag bits as given by the argument. Be aware that that no
memory synchronization is done so the effect of this command might not
immediately show up in other threads. This command may even be used
prior to @code{gcry_check_version}.
@item GCRYCTL_DISABLE_INTERNAL_LOCKING; Arguments: none
This command does nothing. It exists only for backward compatibility.
@item GCRYCTL_ANY_INITIALIZATION_P; Arguments: none
This command returns true if the library has been basically initialized.
Such a basic initialization happens implicitly with many commands to get
certain internal subsystems running. The common and suggested way to
do this basic initialization is by calling gcry_check_version.
@item GCRYCTL_INITIALIZATION_FINISHED; Arguments: none
This command tells the library that the application has finished the
initialization.
@item GCRYCTL_INITIALIZATION_FINISHED_P; Arguments: none
This command returns true if the command@*
GCRYCTL_INITIALIZATION_FINISHED has already been run.
@item GCRYCTL_SET_THREAD_CBS; Arguments: struct ath_ops *ath_ops
This command is obsolete since version 1.6.
@item GCRYCTL_FAST_POLL; Arguments: none
Run a fast random poll.
@item GCRYCTL_SET_RNDEGD_SOCKET; Arguments: const char *filename
This command may be used to override the default name of the EGD socket
to connect to. It may be used only during initialization as it is not
thread safe. Changing the socket name again is not supported. The
function may return an error if the given filename is too long for a
local socket name.
EGD is an alternative random gatherer, used only on systems lacking a
proper random device.
@item GCRYCTL_PRINT_CONFIG; Arguments: FILE *stream
This command dumps information pertaining to the configuration of the
library to the given stream. If NULL is given for @var{stream}, the log
system is used. This command may be used before the initialization has
been finished but not before a @code{gcry_check_version}. Note that
the macro @code{estream_t} can be used instead of @code{gpgrt_stream_t}.
@item GCRYCTL_OPERATIONAL_P; Arguments: none
This command returns true if the library is in an operational state.
This information makes only sense in FIPS mode. In contrast to other
functions, this is a pure test function and won't put the library into
FIPS mode or change the internal state. This command may be used before
the initialization has been finished but not before a @code{gcry_check_version}.
@item GCRYCTL_FIPS_MODE_P; Arguments: none
This command returns true if the library is in FIPS mode. Note, that
this is no indication about the current state of the library. This
command may be used before the initialization has been finished but not
before a @code{gcry_check_version}. An application may use this command or
the convenience macro below to check whether FIPS mode is actually
active.
@deftypefun int gcry_fips_mode_active (void)
Returns true if the FIPS mode is active. Note that this is
implemented as a macro.
@end deftypefun
@item GCRYCTL_FORCE_FIPS_MODE; Arguments: none
Running this command puts the library into FIPS mode. If the library is
already in FIPS mode, a self-test is triggered and thus the library will
be put into operational state. This command may be used before a call
to @code{gcry_check_version} and that is actually the recommended way to let an
application switch the library into FIPS mode. Note that Libgcrypt will
reject an attempt to switch to fips mode during or after the initialization.
@item GCRYCTL_SET_ENFORCED_FIPS_FLAG; Arguments: none
Running this command sets the internal flag that puts the library into
the enforced FIPS mode during the FIPS mode initialization. This command
does not affect the library if the library is not put into the FIPS mode and
it must be used before any other libgcrypt library calls that initialize
the library such as @code{gcry_check_version}. Note that Libgcrypt will
reject an attempt to switch to the enforced fips mode during or after
the initialization.
@item GCRYCTL_SET_PREFERRED_RNG_TYPE; Arguments: int
These are advisory commands to select a certain random number
generator. They are only advisory because libraries may not know what
an application actually wants or vice versa. Thus Libgcrypt employs a
priority check to select the actually used RNG. If an applications
selects a lower priority RNG but a library requests a higher priority
RNG Libgcrypt will switch to the higher priority RNG. Applications
and libraries should use these control codes before
@code{gcry_check_version}. The available generators are:
@table @code
@item GCRY_RNG_TYPE_STANDARD
A conservative standard generator based on the ``Continuously Seeded
Pseudo Random Number Generator'' designed by Peter Gutmann.
@item GCRY_RNG_TYPE_FIPS
A deterministic random number generator conforming to he document
``NIST-Recommended Random Number Generator Based on ANSI X9.31
Appendix A.2.4 Using the 3-Key Triple DES and AES Algorithms''
(2005-01-31). This implementation uses the AES variant.
@item GCRY_RNG_TYPE_SYSTEM
A wrapper around the system's native RNG. On Unix system these are
usually the /dev/random and /dev/urandom devices.
@end table
The default is @code{GCRY_RNG_TYPE_STANDARD} unless FIPS mode as been
enabled; in which case @code{GCRY_RNG_TYPE_FIPS} is used and locked
against further changes.
@item GCRYCTL_GET_CURRENT_RNG_TYPE; Arguments: int *
This command stores the type of the currently used RNG as an integer
value at the provided address.
@item GCRYCTL_SELFTEST; Arguments: none
This may be used at anytime to have the library run all implemented
self-tests. It works in standard and in FIPS mode. Returns 0 on
success or an error code on failure.
@item GCRYCTL_DISABLE_HWF; Arguments: const char *name
Libgcrypt detects certain features of the CPU at startup time. For
performance tests it is sometimes required not to use such a feature.
This option may be used to disable a certain feature; i.e. Libgcrypt
behaves as if this feature has not been detected. This call can be
used several times to disable a set of features, or features may be
given as a colon or comma delimited string. The special feature
"all" can be used to disable all available features.
Note that the detection code might be run if the feature has been
disabled. This command must be used at initialization time;
i.e. before calling @code{gcry_check_version}.
@item GCRYCTL_REINIT_SYSCALL_CLAMP; Arguments: none
Libgcrypt wraps blocking system calls with two functions calls
(``system call clamp'') to give user land threading libraries a hook
for re-scheduling. This works by reading the system call clamp from
Libgpg-error at initialization time. However sometimes Libgcrypt
needs to be initialized before the user land threading systems and at
that point the system call clamp has not been registered with
Libgpg-error and in turn Libgcrypt would not use them. The control
code can be used to tell Libgcrypt that a system call clamp has now
been registered with Libgpg-error and advised it to read the clamp
again. Obviously this control code may only be used before a second
thread is started in a process.
@end table
@end deftypefun
@c **********************************************************
@c ******************* Errors ****************************
@c **********************************************************
@node Error Handling
@section Error Handling
Many functions in Libgcrypt can return an error if they
fail. For this reason, the application should always catch the error
condition and take appropriate measures, for example by releasing the
resources and passing the error up to the caller, or by displaying a
descriptive message to the user and cancelling the operation.
Some error values do not indicate a system error or an error in the
operation, but the result of an operation that failed properly. For
example, if you try to decrypt a tempered message, the decryption will
fail. Another error value actually means that the end of a data
buffer or list has been reached. The following descriptions explain
for many error codes what they mean usually. Some error values have
specific meanings if returned by a certain functions. Such cases are
described in the documentation of those functions.
Libgcrypt uses the @code{libgpg-error} library. This allows to share
the error codes with other components of the GnuPG system, and to pass
error values transparently from the crypto engine, or some helper
application of the crypto engine, to the user. This way no
information is lost. As a consequence, Libgcrypt does not use its own
identifiers for error codes, but uses those provided by
@code{libgpg-error}. They usually start with @code{GPG_ERR_}.
However, Libgcrypt does provide aliases for the functions
defined in libgpg-error, which might be preferred for name space
consistency.
Most functions in Libgcrypt return an error code in the case
of failure. For this reason, the application should always catch the
error condition and take appropriate measures, for example by
releasing the resources and passing the error up to the caller, or by
displaying a descriptive message to the user and canceling the
operation.
Some error values do not indicate a system error or an error in the
operation, but the result of an operation that failed properly.
GnuPG components, including Libgcrypt, use an extra library named
libgpg-error to provide a common error handling scheme. For more
information on libgpg-error, see the according manual.
@menu
* Error Values:: The error value and what it means.
* Error Sources:: A list of important error sources.
* Error Codes:: A list of important error codes.
* Error Strings:: How to get a descriptive string from a value.
@end menu
@node Error Values
@subsection Error Values
@cindex error values
@cindex error codes
@cindex error sources
@deftp {Data type} {gcry_err_code_t}
The @code{gcry_err_code_t} type is an alias for the
@code{libgpg-error} type @code{gpg_err_code_t}. The error code
indicates the type of an error, or the reason why an operation failed.
A list of important error codes can be found in the next section.
@end deftp
@deftp {Data type} {gcry_err_source_t}
The @code{gcry_err_source_t} type is an alias for the
@code{libgpg-error} type @code{gpg_err_source_t}. The error source
has not a precisely defined meaning. Sometimes it is the place where
the error happened, sometimes it is the place where an error was
encoded into an error value. Usually the error source will give an
indication to where to look for the problem. This is not always true,
but it is attempted to achieve this goal.
A list of important error sources can be found in the next section.
@end deftp
@deftp {Data type} {gcry_error_t}
The @code{gcry_error_t} type is an alias for the @code{libgpg-error}
type @code{gpg_error_t}. An error value like this has always two
components, an error code and an error source. Both together form the
error value.
Thus, the error value can not be directly compared against an error
code, but the accessor functions described below must be used.
However, it is guaranteed that only 0 is used to indicate success
(@code{GPG_ERR_NO_ERROR}), and that in this case all other parts of
the error value are set to 0, too.
Note that in Libgcrypt, the error source is used purely for
diagnostic purposes. Only the error code should be checked to test
for a certain outcome of a function. The manual only documents the
error code part of an error value. The error source is left
unspecified and might be anything.
@end deftp
@deftypefun {gcry_err_code_t} gcry_err_code (@w{gcry_error_t @var{err}})
The static inline function @code{gcry_err_code} returns the
@code{gcry_err_code_t} component of the error value @var{err}. This
function must be used to extract the error code from an error value in
order to compare it with the @code{GPG_ERR_*} error code macros.
@end deftypefun
@deftypefun {gcry_err_source_t} gcry_err_source (@w{gcry_error_t @var{err}})
The static inline function @code{gcry_err_source} returns the
@code{gcry_err_source_t} component of the error value @var{err}. This
function must be used to extract the error source from an error value in
order to compare it with the @code{GPG_ERR_SOURCE_*} error source macros.
@end deftypefun
@deftypefun {gcry_error_t} gcry_err_make (@w{gcry_err_source_t @var{source}}, @w{gcry_err_code_t @var{code}})
The static inline function @code{gcry_err_make} returns the error
value consisting of the error source @var{source} and the error code
@var{code}.
This function can be used in callback functions to construct an error
value to return it to the library.
@end deftypefun
@deftypefun {gcry_error_t} gcry_error (@w{gcry_err_code_t @var{code}})
The static inline function @code{gcry_error} returns the error value
consisting of the default error source and the error code @var{code}.
For @acronym{GCRY} applications, the default error source is
@code{GPG_ERR_SOURCE_USER_1}. You can define
@code{GCRY_ERR_SOURCE_DEFAULT} before including @file{gcrypt.h} to
change this default.
This function can be used in callback functions to construct an error
value to return it to the library.
@end deftypefun
The @code{libgpg-error} library provides error codes for all system
error numbers it knows about. If @var{err} is an unknown error
number, the error code @code{GPG_ERR_UNKNOWN_ERRNO} is used. The
following functions can be used to construct error values from system
errno numbers.
@deftypefun {gcry_error_t} gcry_err_make_from_errno (@w{gcry_err_source_t @var{source}}, @w{int @var{err}})
The function @code{gcry_err_make_from_errno} is like
@code{gcry_err_make}, but it takes a system error like @code{errno}
instead of a @code{gcry_err_code_t} error code.
@end deftypefun
@deftypefun {gcry_error_t} gcry_error_from_errno (@w{int @var{err}})
The function @code{gcry_error_from_errno} is like @code{gcry_error},
but it takes a system error like @code{errno} instead of a
@code{gcry_err_code_t} error code.
@end deftypefun
Sometimes you might want to map system error numbers to error codes
directly, or map an error code representing a system error back to the
system error number. The following functions can be used to do that.
@deftypefun {gcry_err_code_t} gcry_err_code_from_errno (@w{int @var{err}})
The function @code{gcry_err_code_from_errno} returns the error code
for the system error @var{err}. If @var{err} is not a known system
error, the function returns @code{GPG_ERR_UNKNOWN_ERRNO}.
@end deftypefun
@deftypefun {int} gcry_err_code_to_errno (@w{gcry_err_code_t @var{err}})
The function @code{gcry_err_code_to_errno} returns the system error
for the error code @var{err}. If @var{err} is not an error code
representing a system error, or if this system error is not defined on
this system, the function returns @code{0}.
@end deftypefun
@node Error Sources
@subsection Error Sources
@cindex error codes, list of
The library @code{libgpg-error} defines an error source for every
component of the GnuPG system. The error source part of an error
value is not well defined. As such it is mainly useful to improve the
diagnostic error message for the user.
If the error code part of an error value is @code{0}, the whole error
value will be @code{0}. In this case the error source part is of
course @code{GPG_ERR_SOURCE_UNKNOWN}.
The list of error sources that might occur in applications using
@acronym{Libgcrypt} is:
@table @code
@item GPG_ERR_SOURCE_UNKNOWN
The error source is not known. The value of this error source is
@code{0}.
@item GPG_ERR_SOURCE_GPGME
The error source is @acronym{GPGME} itself.
@item GPG_ERR_SOURCE_GPG
The error source is GnuPG, which is the crypto engine used for the
OpenPGP protocol.
@item GPG_ERR_SOURCE_GPGSM
The error source is GPGSM, which is the crypto engine used for the
OpenPGP protocol.
@item GPG_ERR_SOURCE_GCRYPT
The error source is @code{libgcrypt}, which is used by crypto engines
to perform cryptographic operations.
@item GPG_ERR_SOURCE_GPGAGENT
The error source is @command{gpg-agent}, which is used by crypto
engines to perform operations with the secret key.
@item GPG_ERR_SOURCE_PINENTRY
The error source is @command{pinentry}, which is used by
@command{gpg-agent} to query the passphrase to unlock a secret key.
@item GPG_ERR_SOURCE_SCD
The error source is the SmartCard Daemon, which is used by
@command{gpg-agent} to delegate operations with the secret key to a
SmartCard.
@item GPG_ERR_SOURCE_KEYBOX
The error source is @code{libkbx}, a library used by the crypto
engines to manage local keyrings.
@item GPG_ERR_SOURCE_USER_1
@item GPG_ERR_SOURCE_USER_2
@item GPG_ERR_SOURCE_USER_3
@item GPG_ERR_SOURCE_USER_4
These error sources are not used by any GnuPG component and can be
used by other software. For example, applications using
Libgcrypt can use them to mark error values coming from callback
handlers. Thus @code{GPG_ERR_SOURCE_USER_1} is the default for errors
created with @code{gcry_error} and @code{gcry_error_from_errno},
unless you define @code{GCRY_ERR_SOURCE_DEFAULT} before including
@file{gcrypt.h}.
@end table
@node Error Codes
@subsection Error Codes
@cindex error codes, list of
The library @code{libgpg-error} defines many error values. The
following list includes the most important error codes.
@table @code
@item GPG_ERR_EOF
This value indicates the end of a list, buffer or file.
@item GPG_ERR_NO_ERROR
This value indicates success. The value of this error code is
@code{0}. Also, it is guaranteed that an error value made from the
error code @code{0} will be @code{0} itself (as a whole). This means
that the error source information is lost for this error code,
however, as this error code indicates that no error occurred, this is
generally not a problem.
@item GPG_ERR_GENERAL
This value means that something went wrong, but either there is not
enough information about the problem to return a more useful error
value, or there is no separate error value for this type of problem.
@item GPG_ERR_ENOMEM
This value means that an out-of-memory condition occurred.
@item GPG_ERR_E...
System errors are mapped to GPG_ERR_EFOO where FOO is the symbol for
the system error.
@item GPG_ERR_INV_VALUE
This value means that some user provided data was out of range.
@item GPG_ERR_UNUSABLE_PUBKEY
This value means that some recipients for a message were invalid.
@item GPG_ERR_UNUSABLE_SECKEY
This value means that some signers were invalid.
@item GPG_ERR_NO_DATA
This value means that data was expected where no data was found.
@item GPG_ERR_CONFLICT
This value means that a conflict of some sort occurred.
@item GPG_ERR_NOT_IMPLEMENTED
This value indicates that the specific function (or operation) is not
implemented. This error should never happen. It can only occur if
you use certain values or configuration options which do not work,
but for which we think that they should work at some later time.
@item GPG_ERR_DECRYPT_FAILED
This value indicates that a decryption operation was unsuccessful.
@item GPG_ERR_WRONG_KEY_USAGE
This value indicates that a key is not used appropriately.
@item GPG_ERR_NO_SECKEY
This value indicates that no secret key for the user ID is available.
@item GPG_ERR_UNSUPPORTED_ALGORITHM
This value means a verification failed because the cryptographic
algorithm is not supported by the crypto backend.
@item GPG_ERR_BAD_SIGNATURE
This value means a verification failed because the signature is bad.
@item GPG_ERR_NO_PUBKEY
This value means a verification failed because the public key is not
available.
@item GPG_ERR_NOT_OPERATIONAL
This value means that the library is not yet in state which allows to
use this function. This error code is in particular returned if
Libgcrypt is operated in FIPS mode and the internal state of the
library does not yet or not anymore allow the use of a service.
This error code is only available with newer libgpg-error versions, thus
you might see ``invalid error code'' when passing this to
@code{gpg_strerror}. The numeric value of this error code is 176.
@item GPG_ERR_USER_1
@item GPG_ERR_USER_2
@item ...
@item GPG_ERR_USER_16
These error codes are not used by any GnuPG component and can be
freely used by other software. Applications using Libgcrypt
might use them to mark specific errors returned by callback handlers
if no suitable error codes (including the system errors) for these
errors exist already.
@end table
@node Error Strings
@subsection Error Strings
@cindex error values, printing of
@cindex error codes, printing of
@cindex error sources, printing of
@cindex error strings
@deftypefun {const char *} gcry_strerror (@w{gcry_error_t @var{err}})
The function @code{gcry_strerror} returns a pointer to a statically
allocated string containing a description of the error code contained
in the error value @var{err}. This string can be used to output a
diagnostic message to the user.
@end deftypefun
@deftypefun {const char *} gcry_strsource (@w{gcry_error_t @var{err}})
The function @code{gcry_strsource} returns a pointer to a statically
allocated string containing a description of the error source
contained in the error value @var{err}. This string can be used to
output a diagnostic message to the user.
@end deftypefun
The following example illustrates the use of the functions described
above:
@example
@{
gcry_cipher_hd_t handle;
gcry_error_t err = 0;
err = gcry_cipher_open (&handle, GCRY_CIPHER_AES,
GCRY_CIPHER_MODE_CBC, 0);
if (err)
@{
fprintf (stderr, "Failure: %s/%s\n",
gcry_strsource (err),
gcry_strerror (err));
@}
@}
@end example
@c **********************************************************
@c ******************* General ****************************
@c **********************************************************
@node Handler Functions
@chapter Handler Functions
Libgcrypt makes it possible to install so called `handler functions',
which get called by Libgcrypt in case of certain events.
@menu
* Progress handler:: Using a progress handler function.
* Allocation handler:: Using special memory allocation functions.
* Error handler:: Using error handler functions.
* Logging handler:: Using a special logging function.
@end menu
@node Progress handler
@section Progress handler
It is often useful to retrieve some feedback while long running
operations are performed.
@deftp {Data type} gcry_handler_progress_t
Progress handler functions have to be of the type
@code{gcry_handler_progress_t}, which is defined as:
@code{void (*gcry_handler_progress_t) (void *, const char *, int, int, int)}
@end deftp
The following function may be used to register a handler function for
this purpose.
@deftypefun void gcry_set_progress_handler (gcry_handler_progress_t @var{cb}, void *@var{cb_data})
This function installs @var{cb} as the `Progress handler' function.
It may be used only during initialization. @var{cb} must be defined
as follows:
@example
void
my_progress_handler (void *@var{cb_data}, const char *@var{what},
int @var{printchar}, int @var{current}, int @var{total})
@{
/* Do something. */
@}
@end example
A description of the arguments of the progress handler function follows.
@table @var
@item cb_data
The argument provided in the call to @code{gcry_set_progress_handler}.
@item what
A string identifying the type of the progress output. The following
values for @var{what} are defined:
@table @code
@item need_entropy
Not enough entropy is available. @var{total} holds the number of
required bytes.
@item wait_dev_random
Waiting to re-open a random device. @var{total} gives the number of
seconds until the next try.
@item primegen
Values for @var{printchar}:
@table @code
@item \n
Prime generated.
@item !
Need to refresh the pool of prime numbers.
@item <, >
Number of bits adjusted.
@item ^
Searching for a generator.
@item .
Fermat test on 10 candidates failed.
@item :
Restart with a new random value.
@item +
Rabin Miller test passed.
@end table
@end table
@end table
@end deftypefun
@node Allocation handler
@section Allocation handler
It is possible to make Libgcrypt use special memory
allocation functions instead of the built-in ones.
Memory allocation functions are of the following types:
@deftp {Data type} gcry_handler_alloc_t
This type is defined as: @code{void *(*gcry_handler_alloc_t) (size_t n)}.
@end deftp
@deftp {Data type} gcry_handler_secure_check_t
This type is defined as: @code{int *(*gcry_handler_secure_check_t) (const void *)}.
@end deftp
@deftp {Data type} gcry_handler_realloc_t
This type is defined as: @code{void *(*gcry_handler_realloc_t) (void *p, size_t n)}.
@end deftp
@deftp {Data type} gcry_handler_free_t
This type is defined as: @code{void *(*gcry_handler_free_t) (void *)}.
@end deftp
Special memory allocation functions can be installed with the
following function:
@deftypefun void gcry_set_allocation_handler (gcry_handler_alloc_t @var{func_alloc}, gcry_handler_alloc_t @var{func_alloc_secure}, gcry_handler_secure_check_t @var{func_secure_check}, gcry_handler_realloc_t @var{func_realloc}, gcry_handler_free_t @var{func_free})
Install the provided functions and use them instead of the built-in
functions for doing memory allocation. Using this function is in
general not recommended because the standard Libgcrypt allocation
functions are guaranteed to zeroize memory if needed.
This function may be used only during initialization and may not be
used in fips mode.
@end deftypefun
@node Error handler
@section Error handler
The following functions may be used to register handler functions that
are called by Libgcrypt in case certain error conditions occur. They
may and should be registered prior to calling @code{gcry_check_version}.
@deftp {Data type} gcry_handler_no_mem_t
This type is defined as: @code{int (*gcry_handler_no_mem_t) (void *, size_t, unsigned int)}
@end deftp
@deftypefun void gcry_set_outofcore_handler (gcry_handler_no_mem_t @var{func_no_mem}, void *@var{cb_data})
This function registers @var{func_no_mem} as `out-of-core handler',
which means that it will be called in the case of not having enough
memory available. The handler is called with 3 arguments: The first
one is the pointer @var{cb_data} as set with this function, the second
is the requested memory size and the last being a flag. If bit 0 of
the flag is set, secure memory has been requested. The handler should
either return true to indicate that Libgcrypt should try again
allocating memory or return false to let Libgcrypt use its default
fatal error handler.
@end deftypefun
@deftp {Data type} gcry_handler_error_t
This type is defined as: @code{void (*gcry_handler_error_t) (void *, int, const char *)}
@end deftp
@deftypefun void gcry_set_fatalerror_handler (gcry_handler_error_t @var{func_error}, void *@var{cb_data})
This function registers @var{func_error} as `error handler',
which means that it will be called in error conditions.
@end deftypefun
@node Logging handler
@section Logging handler
@deftp {Data type} gcry_handler_log_t
This type is defined as: @code{void (*gcry_handler_log_t) (void *, int, const char *, va_list)}
@end deftp
@deftypefun void gcry_set_log_handler (gcry_handler_log_t @var{func_log}, void *@var{cb_data})
This function registers @var{func_log} as `logging handler', which means
that it will be called in case Libgcrypt wants to log a message. This
function may and should be used prior to calling
@code{gcry_check_version}.
@end deftypefun
@c **********************************************************
@c ******************* Ciphers ****************************
@c **********************************************************
@c @include cipher-ref.texi
@node Symmetric cryptography
@chapter Symmetric cryptography
The cipher functions are used for symmetrical cryptography,
i.e. cryptography using a shared key. The programming model follows
an open/process/close paradigm and is in that similar to other
building blocks provided by Libgcrypt.
@menu
* Available ciphers:: List of ciphers supported by the library.
* Available cipher modes:: List of cipher modes supported by the library.
* Working with cipher handles:: How to perform operations related to cipher handles.
* General cipher functions:: General cipher functions independent of cipher handles.
@end menu
@node Available ciphers
@section Available ciphers
@table @code
@item GCRY_CIPHER_NONE
This is not a real algorithm but used by some functions as error return.
The value always evaluates to false.
@item GCRY_CIPHER_IDEA
@cindex IDEA
This is the IDEA algorithm.
@item GCRY_CIPHER_3DES
@cindex 3DES
@cindex Triple-DES
@cindex DES-EDE
@cindex Digital Encryption Standard
Triple-DES with 3 Keys as EDE. The key size of this algorithm is 168 but
you have to pass 192 bits because the most significant bits of each byte
are ignored.
@item GCRY_CIPHER_CAST5
@cindex CAST5
CAST128-5 block cipher algorithm. The key size is 128 bits.
@item GCRY_CIPHER_BLOWFISH
@cindex Blowfish
The blowfish algorithm. The current implementation allows only for a key
size of 128 bits.
@item GCRY_CIPHER_SAFER_SK128
Reserved and not currently implemented.
@item GCRY_CIPHER_DES_SK
Reserved and not currently implemented.
@item GCRY_CIPHER_AES
@itemx GCRY_CIPHER_AES128
@itemx GCRY_CIPHER_RIJNDAEL
@itemx GCRY_CIPHER_RIJNDAEL128
@cindex Rijndael
@cindex AES
@cindex Advanced Encryption Standard
AES (Rijndael) with a 128 bit key.
@item GCRY_CIPHER_AES192
@itemx GCRY_CIPHER_RIJNDAEL192
AES (Rijndael) with a 192 bit key.
@item GCRY_CIPHER_AES256
@itemx GCRY_CIPHER_RIJNDAEL256
AES (Rijndael) with a 256 bit key.
@item GCRY_CIPHER_TWOFISH
@cindex Twofish
The Twofish algorithm with a 256 bit key.
@item GCRY_CIPHER_TWOFISH128
The Twofish algorithm with a 128 bit key.
@item GCRY_CIPHER_ARCFOUR
@cindex Arcfour
@cindex RC4
An algorithm which is 100% compatible with RSA Inc.'s RC4 algorithm.
Note that this is a stream cipher and must be used very carefully to
avoid a couple of weaknesses.
@item GCRY_CIPHER_DES
@cindex DES
Standard DES with a 56 bit key. You need to pass 64 bit but the high
bits of each byte are ignored. Note, that this is a weak algorithm
which can be broken in reasonable time using a brute force approach.
@item GCRY_CIPHER_SERPENT128
@itemx GCRY_CIPHER_SERPENT192
@itemx GCRY_CIPHER_SERPENT256
@cindex Serpent
The Serpent cipher from the AES contest.
@item GCRY_CIPHER_RFC2268_40
@itemx GCRY_CIPHER_RFC2268_128
@cindex rfc-2268
@cindex RC2
Ron's Cipher 2 in the 40 and 128 bit variants.
@item GCRY_CIPHER_SEED
@cindex Seed (cipher)
A 128 bit cipher as described by RFC4269.
@item GCRY_CIPHER_CAMELLIA128
@itemx GCRY_CIPHER_CAMELLIA192
@itemx GCRY_CIPHER_CAMELLIA256
@cindex Camellia
The Camellia cipher by NTT. See
@uref{http://info.isl.ntt.co.jp/@/crypt/@/eng/@/camellia/@/specifications.html}.
@item GCRY_CIPHER_SALSA20
@cindex Salsa20
This is the Salsa20 stream cipher.
@item GCRY_CIPHER_SALSA20R12
@cindex Salsa20/12
This is the Salsa20/12 - reduced round version of Salsa20 stream cipher.
@item GCRY_CIPHER_GOST28147
@cindex GOST 28147-89
The GOST 28147-89 cipher, defined in the respective GOST standard.
Translation of this GOST into English is provided in the RFC-5830.
@item GCRY_CIPHER_CHACHA20
@cindex ChaCha20
This is the ChaCha20 stream cipher.
@end table
@node Available cipher modes
@section Available cipher modes
@table @code
@item GCRY_CIPHER_MODE_NONE
No mode specified. This should not be used. The only exception is that
if Libgcrypt is not used in FIPS mode and if any debug flag has been
set, this mode may be used to bypass the actual encryption.
@item GCRY_CIPHER_MODE_ECB
@cindex ECB, Electronic Codebook mode
Electronic Codebook mode.
@item GCRY_CIPHER_MODE_CFB
@item GCRY_CIPHER_MODE_CFB8
@cindex CFB, Cipher Feedback mode
Cipher Feedback mode. For GCRY_CIPHER_MODE_CFB the shift size equals
the block size of the cipher (e.g. for AES it is CFB-128). For
GCRY_CIPHER_MODE_CFB8 the shift size is 8 bit but that variant is not
yet available.
@item GCRY_CIPHER_MODE_CBC
@cindex CBC, Cipher Block Chaining mode
Cipher Block Chaining mode.
@item GCRY_CIPHER_MODE_STREAM
Stream mode, only to be used with stream cipher algorithms.
@item GCRY_CIPHER_MODE_OFB
@cindex OFB, Output Feedback mode
Output Feedback mode.
@item GCRY_CIPHER_MODE_CTR
@cindex CTR, Counter mode
Counter mode.
@item GCRY_CIPHER_MODE_AESWRAP
@cindex AES-Wrap mode
This mode is used to implement the AES-Wrap algorithm according to
RFC-3394. It may be used with any 128 bit block length algorithm,
however the specs require one of the 3 AES algorithms. These special
conditions apply: If @code{gcry_cipher_setiv} has not been used the
standard IV is used; if it has been used the lower 64 bit of the IV
are used as the Alternative Initial Value. On encryption the provided
output buffer must be 64 bit (8 byte) larger than the input buffer;
in-place encryption is still allowed. On decryption the output buffer
may be specified 64 bit (8 byte) shorter than then input buffer. As
per specs the input length must be at least 128 bits and the length
must be a multiple of 64 bits.
@item GCRY_CIPHER_MODE_CCM
@cindex CCM, Counter with CBC-MAC mode
Counter with CBC-MAC mode is an Authenticated Encryption with
Associated Data (AEAD) block cipher mode, which is specified in
'NIST Special Publication 800-38C' and RFC 3610.
@item GCRY_CIPHER_MODE_GCM
@cindex GCM, Galois/Counter Mode
Galois/Counter Mode (GCM) is an Authenticated Encryption with
Associated Data (AEAD) block cipher mode, which is specified in
'NIST Special Publication 800-38D'.
@item GCRY_CIPHER_MODE_POLY1305
@cindex Poly1305 based AEAD mode with ChaCha20
This mode implements the Poly1305 Authenticated Encryption with Associated
Data (AEAD) mode according to RFC-7539. This mode can be used with ChaCha20
stream cipher.
@item GCRY_CIPHER_MODE_OCB
@cindex OCB, OCB3
OCB is an Authenticated Encryption with Associated Data (AEAD) block
cipher mode, which is specified in RFC-7253. Supported tag lengths
are 128, 96, and 64 bit with the default being 128 bit. To switch to
a different tag length @code{gcry_cipher_ctl} using the command
@code{GCRYCTL_SET_TAGLEN} and the address of an @code{int} variable
set to 12 (for 96 bit) or 8 (for 64 bit) provided for the
@code{buffer} argument and @code{sizeof(int)} for @code{buflen}.
Note that the use of @code{gcry_cipher_final} is required.
@item GCRY_CIPHER_MODE_XTS
@cindex XTS, XTS mode
XEX-based tweaked-codebook mode with ciphertext stealing (XTS) mode
is used to implement the AES-XTS as specified in IEEE 1619 Standard
Architecture for Encrypted Shared Storage Media and NIST SP800-38E.
The XTS mode requires doubling key-length, for example, using 512-bit
key with AES-256 (@code{GCRY_CIPHER_AES256}). The 128-bit tweak value
is feed to XTS mode as little-endian byte array using
@code{gcry_cipher_setiv} function. When encrypting or decrypting,
full-sized data unit buffers needs to be passed to
@code{gcry_cipher_encrypt} or @code{gcry_cipher_decrypt}. The tweak
value is automatically incremented after each call of
@code{gcry_cipher_encrypt} and @code{gcry_cipher_decrypt}.
Auto-increment allows avoiding need of setting IV between processing
of sequential data units.
@end table
@node Working with cipher handles
@section Working with cipher handles
To use a cipher algorithm, you must first allocate an according
handle. This is to be done using the open function:
@deftypefun gcry_error_t gcry_cipher_open (gcry_cipher_hd_t *@var{hd}, int @var{algo}, int @var{mode}, unsigned int @var{flags})
This function creates the context handle required for most of the
other cipher functions and returns a handle to it in `hd'. In case of
an error, an according error code is returned.
The ID of algorithm to use must be specified via @var{algo}. See
@xref{Available ciphers}, for a list of supported ciphers and the
according constants.
Besides using the constants directly, the function
@code{gcry_cipher_map_name} may be used to convert the textual name of
an algorithm into the according numeric ID.
The cipher mode to use must be specified via @var{mode}. See
@xref{Available cipher modes}, for a list of supported cipher modes
and the according constants. Note that some modes are incompatible
with some algorithms - in particular, stream mode
(@code{GCRY_CIPHER_MODE_STREAM}) only works with stream ciphers.
Poly1305 AEAD mode (@code{GCRY_CIPHER_MODE_POLY1305}) only works with
ChaCha20 stream cipher. The block cipher modes
(@code{GCRY_CIPHER_MODE_ECB}, @code{GCRY_CIPHER_MODE_CBC},
@code{GCRY_CIPHER_MODE_CFB}, @code{GCRY_CIPHER_MODE_OFB} and
@code{GCRY_CIPHER_MODE_CTR}) will work with any block cipher
algorithm. GCM mode (@code{GCRY_CIPHER_MODE_CCM}), CCM mode
(@code{GCRY_CIPHER_MODE_GCM}), OCB mode (@code{GCRY_CIPHER_MODE_OCB}),
and XTS mode (@code{GCRY_CIPHER_MODE_XTS}) will only work
with block cipher algorithms which have the block size of 16 bytes.
The third argument @var{flags} can either be passed as @code{0} or as
the bit-wise OR of the following constants.
@table @code
@item GCRY_CIPHER_SECURE
Make sure that all operations are allocated in secure memory. This is
useful when the key material is highly confidential.
@item GCRY_CIPHER_ENABLE_SYNC
@cindex sync mode (OpenPGP)
This flag enables the CFB sync mode, which is a special feature of
Libgcrypt's CFB mode implementation to allow for OpenPGP's CFB variant.
See @code{gcry_cipher_sync}.
@item GCRY_CIPHER_CBC_CTS
@cindex cipher text stealing
Enable cipher text stealing (CTS) for the CBC mode. Cannot be used
simultaneous as GCRY_CIPHER_CBC_MAC. CTS mode makes it possible to
transform data of almost arbitrary size (only limitation is that it
must be greater than the algorithm's block size).
@item GCRY_CIPHER_CBC_MAC
@cindex CBC-MAC
Compute CBC-MAC keyed checksums. This is the same as CBC mode, but
only output the last block. Cannot be used simultaneous as
GCRY_CIPHER_CBC_CTS.
@end table
@end deftypefun
Use the following function to release an existing handle:
@deftypefun void gcry_cipher_close (gcry_cipher_hd_t @var{h})
This function releases the context created by @code{gcry_cipher_open}.
It also zeroises all sensitive information associated with this cipher
handle.
@end deftypefun
In order to use a handle for performing cryptographic operations, a
`key' has to be set first:
@deftypefun gcry_error_t gcry_cipher_setkey (gcry_cipher_hd_t @var{h}, const void *@var{k}, size_t @var{l})
Set the key @var{k} used for encryption or decryption in the context
denoted by the handle @var{h}. The length @var{l} (in bytes) of the
key @var{k} must match the required length of the algorithm set for
this context or be in the allowed range for algorithms with variable
key size. The function checks this and returns an error if there is a
problem. A caller should always check for an error.
@end deftypefun
Most crypto modes requires an initialization vector (IV), which
usually is a non-secret random string acting as a kind of salt value.
The CTR mode requires a counter, which is also similar to a salt
value. To set the IV or CTR, use these functions:
@deftypefun gcry_error_t gcry_cipher_setiv (gcry_cipher_hd_t @var{h}, const void *@var{k}, size_t @var{l})
Set the initialization vector used for encryption or decryption. The
vector is passed as the buffer @var{K} of length @var{l} bytes and
copied to internal data structures. The function checks that the IV
matches the requirement of the selected algorithm and mode.
This function is also used by AEAD modes and with Salsa20 and ChaCha20
stream ciphers to set or update the required nonce. In these cases it
needs to be called after setting the key.
@end deftypefun
@deftypefun gcry_error_t gcry_cipher_setctr (gcry_cipher_hd_t @var{h}, const void *@var{c}, size_t @var{l})
Set the counter vector used for encryption or decryption. The counter
is passed as the buffer @var{c} of length @var{l} bytes and copied to
internal data structures. The function checks that the counter
matches the requirement of the selected algorithm (i.e., it must be
the same size as the block size).
@end deftypefun
@deftypefun gcry_error_t gcry_cipher_reset (gcry_cipher_hd_t @var{h})
Set the given handle's context back to the state it had after the last
call to gcry_cipher_setkey and clear the initialization vector.
Note that gcry_cipher_reset is implemented as a macro.
@end deftypefun
Authenticated Encryption with Associated Data (AEAD) block cipher
modes require the handling of the authentication tag and the additional
authenticated data, which can be done by using the following
functions:
@deftypefun gcry_error_t gcry_cipher_authenticate (gcry_cipher_hd_t @var{h}, const void *@var{abuf}, size_t @var{abuflen})
Process the buffer @var{abuf} of length @var{abuflen} as the additional
authenticated data (AAD) for AEAD cipher modes.
@end deftypefun
@deftypefun {gcry_error_t} gcry_cipher_gettag @
(@w{gcry_cipher_hd_t @var{h}}, @
@w{void *@var{tag}}, @w{size_t @var{taglen}})
This function is used to read the authentication tag after encryption.
The function finalizes and outputs the authentication tag to the buffer
@var{tag} of length @var{taglen} bytes.
Depending on the used mode certain restrictions for @var{taglen} are
enforced: For GCM @var{taglen} must be at least 16 or one of the
allowed truncated lengths (4, 8, 12, 13, 14, or 15).
@end deftypefun
@deftypefun {gcry_error_t} gcry_cipher_checktag @
(@w{gcry_cipher_hd_t @var{h}}, @
@w{const void *@var{tag}}, @w{size_t @var{taglen}})
Check the authentication tag after decryption. The authentication
tag is passed as the buffer @var{tag} of length @var{taglen} bytes
and compared to internal authentication tag computed during
decryption. Error code @code{GPG_ERR_CHECKSUM} is returned if
the authentication tag in the buffer @var{tag} does not match
the authentication tag calculated during decryption.
Depending on the used mode certain restrictions for @var{taglen} are
enforced: For GCM @var{taglen} must either be 16 or one of the allowed
truncated lengths (4, 8, 12, 13, 14, or 15).
@end deftypefun
The actual encryption and decryption is done by using one of the
following functions. They may be used as often as required to process
all the data.
@deftypefun gcry_error_t gcry_cipher_encrypt (gcry_cipher_hd_t @var{h}, unsigned char *{out}, size_t @var{outsize}, const unsigned char *@var{in}, size_t @var{inlen})
@code{gcry_cipher_encrypt} is used to encrypt the data. This function
can either work in place or with two buffers. It uses the cipher
context already setup and described by the handle @var{h}. There are 2
ways to use the function: If @var{in} is passed as @code{NULL} and
@var{inlen} is @code{0}, in-place encryption of the data in @var{out} of
length @var{outsize} takes place. With @var{in} being not @code{NULL},
@var{inlen} bytes are encrypted to the buffer @var{out} which must have
at least a size of @var{inlen}. @var{outsize} must be set to the
allocated size of @var{out}, so that the function can check that there
is sufficient space. Note that overlapping buffers are not allowed.
Depending on the selected algorithms and encryption mode, the length of
the buffers must be a multiple of the block size.
Some encryption modes require that @code{gcry_cipher_final} is used
before the final data chunk is passed to this function.
The function returns @code{0} on success or an error code.
@end deftypefun
@deftypefun gcry_error_t gcry_cipher_decrypt (gcry_cipher_hd_t @var{h}, unsigned char *{out}, size_t @var{outsize}, const unsigned char *@var{in}, size_t @var{inlen})
@code{gcry_cipher_decrypt} is used to decrypt the data. This function
can either work in place or with two buffers. It uses the cipher
context already setup and described by the handle @var{h}. There are 2
ways to use the function: If @var{in} is passed as @code{NULL} and
@var{inlen} is @code{0}, in-place decryption of the data in @var{out} or
length @var{outsize} takes place. With @var{in} being not @code{NULL},
@var{inlen} bytes are decrypted to the buffer @var{out} which must have
at least a size of @var{inlen}. @var{outsize} must be set to the
allocated size of @var{out}, so that the function can check that there
is sufficient space. Note that overlapping buffers are not allowed.
Depending on the selected algorithms and encryption mode, the length of
the buffers must be a multiple of the block size.
Some encryption modes require that @code{gcry_cipher_final} is used
before the final data chunk is passed to this function.
The function returns @code{0} on success or an error code.
@end deftypefun
The OCB mode features integrated padding and must thus be told about
the end of the input data. This is done with:
@deftypefun gcry_error_t gcry_cipher_final (gcry_cipher_hd_t @var{h})
Set a flag in the context to tell the encrypt and decrypt functions
that their next call will provide the last chunk of data. Only the
first call to this function has an effect and only for modes which
support it. Checking the error is in general not necessary. This is
implemented as a macro.
@end deftypefun
OpenPGP (as defined in RFC-4880) requires a special sync operation in
some places. The following function is used for this:
@deftypefun gcry_error_t gcry_cipher_sync (gcry_cipher_hd_t @var{h})
Perform the OpenPGP sync operation on context @var{h}. Note that this
is a no-op unless the context was created with the flag
@code{GCRY_CIPHER_ENABLE_SYNC}
@end deftypefun
Some of the described functions are implemented as macros utilizing a
catch-all control function. This control function is rarely used
directly but there is nothing which would inhibit it:
@deftypefun gcry_error_t gcry_cipher_ctl (gcry_cipher_hd_t @var{h}, int @var{cmd}, void *@var{buffer}, size_t @var{buflen})
@code{gcry_cipher_ctl} controls various aspects of the cipher module and
specific cipher contexts. Usually some more specialized functions or
macros are used for this purpose. The semantics of the function and its
parameters depends on the the command @var{cmd} and the passed context
handle @var{h}. Please see the comments in the source code
(@code{src/global.c}) for details.
@end deftypefun
@deftypefun gcry_error_t gcry_cipher_info (gcry_cipher_hd_t @var{h}, @
int @var{what}, void *@var{buffer}, size_t *@var{nbytes})
@code{gcry_cipher_info} is used to retrieve various
information about a cipher context or the cipher module in general.
@c begin constants for gcry_cipher_info
@table @code
@item GCRYCTL_GET_TAGLEN:
Return the length of the tag for an AE algorithm mode. An error is
returned for modes which do not support a tag. @var{buffer} must be
given as NULL. On success the result is stored @var{nbytes}. The
taglen is returned in bytes.
@end table
@c end constants for gcry_cipher_info
@end deftypefun
@node General cipher functions
@section General cipher functions
To work with the algorithms, several functions are available to map
algorithm names to the internal identifiers, as well as ways to
retrieve information about an algorithm or the current cipher context.
@deftypefun gcry_error_t gcry_cipher_algo_info (int @var{algo}, int @var{what}, void *@var{buffer}, size_t *@var{nbytes})
This function is used to retrieve information on a specific algorithm.
You pass the cipher algorithm ID as @var{algo} and the type of
information requested as @var{what}. The result is either returned as
the return code of the function or copied to the provided @var{buffer}
whose allocated length must be available in an integer variable with the
address passed in @var{nbytes}. This variable will also receive the
actual used length of the buffer.
Here is a list of supported codes for @var{what}:
@c begin constants for gcry_cipher_algo_info
@table @code
@item GCRYCTL_GET_KEYLEN:
Return the length of the key. If the algorithm supports multiple key
lengths, the maximum supported value is returned. The length is
returned as number of octets (bytes) and not as number of bits in
@var{nbytes}; @var{buffer} must be zero. Note that it is usually
better to use the convenience function
@code{gcry_cipher_get_algo_keylen}.
@item GCRYCTL_GET_BLKLEN:
Return the block length of the algorithm. The length is returned as a
number of octets in @var{nbytes}; @var{buffer} must be zero. Note
that it is usually better to use the convenience function
@code{gcry_cipher_get_algo_blklen}.
@item GCRYCTL_TEST_ALGO:
Returns @code{0} when the specified algorithm is available for use.
@var{buffer} and @var{nbytes} must be zero.
@end table
@c end constants for gcry_cipher_algo_info
@end deftypefun
@c end gcry_cipher_algo_info
@deftypefun size_t gcry_cipher_get_algo_keylen (@var{algo})
This function returns length of the key for algorithm @var{algo}. If
the algorithm supports multiple key lengths, the maximum supported key
length is returned. On error @code{0} is returned. The key length is
returned as number of octets.
This is a convenience functions which should be preferred over
@code{gcry_cipher_algo_info} because it allows for proper type
checking.
@end deftypefun
@c end gcry_cipher_get_algo_keylen
@deftypefun size_t gcry_cipher_get_algo_blklen (int @var{algo})
This functions returns the block-length of the algorithm @var{algo}
counted in octets. On error @code{0} is returned.
This is a convenience functions which should be preferred over
@code{gcry_cipher_algo_info} because it allows for proper type
checking.
@end deftypefun
@c end gcry_cipher_get_algo_blklen
@deftypefun {const char *} gcry_cipher_algo_name (int @var{algo})
@code{gcry_cipher_algo_name} returns a string with the name of the
cipher algorithm @var{algo}. If the algorithm is not known or another
error occurred, the string @code{"?"} is returned. This function should
not be used to test for the availability of an algorithm.
@end deftypefun
@deftypefun int gcry_cipher_map_name (const char *@var{name})
@code{gcry_cipher_map_name} returns the algorithm identifier for the
cipher algorithm described by the string @var{name}. If this algorithm
is not available @code{0} is returned.
@end deftypefun
@deftypefun int gcry_cipher_mode_from_oid (const char *@var{string})
Return the cipher mode associated with an @acronym{ASN.1} object
identifier. The object identifier is expected to be in the
@acronym{IETF}-style dotted decimal notation. The function returns
@code{0} for an unknown object identifier or when no mode is associated
with it.
@end deftypefun
@c **********************************************************
@c ******************* Public Key *************************
@c **********************************************************
@node Public Key cryptography
@chapter Public Key cryptography
Public key cryptography, also known as asymmetric cryptography, is an
easy way for key management and to provide digital signatures.
Libgcrypt provides two completely different interfaces to
public key cryptography, this chapter explains the one based on
S-expressions.
@menu
* Available algorithms:: Algorithms supported by the library.
* Used S-expressions:: Introduction into the used S-expression.
* Cryptographic Functions:: Functions for performing the cryptographic actions.
* General public-key related Functions:: General functions, not implementing any cryptography.
@end menu
@node Available algorithms
@section Available algorithms
Libgcrypt supports the RSA (Rivest-Shamir-Adleman) algorithms as well
as DSA (Digital Signature Algorithm) and Elgamal. The versatile
interface allows to add more algorithms in the future.
@node Used S-expressions
@section Used S-expressions
Libgcrypt's API for asymmetric cryptography is based on data structures
called S-expressions (see
@uref{http://people.csail.mit.edu/@/rivest/@/sexp.html}) and does not work
with contexts as most of the other building blocks of Libgcrypt do.
@noindent
The following information are stored in S-expressions:
@itemize
@item keys
@item plain text data
@item encrypted data
@item signatures
@end itemize
@noindent
To describe how Libgcrypt expect keys, we use examples. Note that
words in
@ifnottex
uppercase
@end ifnottex
@iftex
italics
@end iftex
indicate parameters whereas lowercase words are literals.
Note that all MPI (multi-precision-integers) values are expected to be in
@code{GCRYMPI_FMT_USG} format. An easy way to create S-expressions is
by using @code{gcry_sexp_build} which allows to pass a string with
printf-like escapes to insert MPI values.
@menu
* RSA key parameters:: Parameters used with an RSA key.
* DSA key parameters:: Parameters used with a DSA key.
* ECC key parameters:: Parameters used with ECC keys.
@end menu
@node RSA key parameters
@subsection RSA key parameters
@noindent
An RSA private key is described by this S-expression:
@example
(private-key
(rsa
(n @var{n-mpi})
(e @var{e-mpi})
(d @var{d-mpi})
(p @var{p-mpi})
(q @var{q-mpi})
(u @var{u-mpi})))
@end example
@noindent
An RSA public key is described by this S-expression:
@example
(public-key
(rsa
(n @var{n-mpi})
(e @var{e-mpi})))
@end example
@table @var
@item n-mpi
RSA public modulus @math{n}.
@item e-mpi
RSA public exponent @math{e}.
@item d-mpi
RSA secret exponent @math{d = e^{-1} \bmod (p-1)(q-1)}.
@item p-mpi
RSA secret prime @math{p}.
@item q-mpi
RSA secret prime @math{q} with @math{p < q}.
@item u-mpi
Multiplicative inverse @math{u = p^{-1} \bmod q}.
@end table
For signing and decryption the parameters @math{(p, q, u)} are optional
but greatly improve the performance. Either all of these optional
parameters must be given or none of them. They are mandatory for
gcry_pk_testkey.
Note that OpenSSL uses slighly different parameters: @math{q < p} and
@math{u = q^{-1} \bmod p}. To use these parameters you will need to
swap the values and recompute @math{u}. Here is example code to do this:
@example
if (gcry_mpi_cmp (p, q) > 0)
@{
gcry_mpi_swap (p, q);
gcry_mpi_invm (u, p, q);
@}
@end example
@node DSA key parameters
@subsection DSA key parameters
@noindent
A DSA private key is described by this S-expression:
@example
(private-key
(dsa
(p @var{p-mpi})
(q @var{q-mpi})
(g @var{g-mpi})
(y @var{y-mpi})
(x @var{x-mpi})))
@end example
@table @var
@item p-mpi
DSA prime @math{p}.
@item q-mpi
DSA group order @math{q} (which is a prime divisor of @math{p-1}).
@item g-mpi
DSA group generator @math{g}.
@item y-mpi
DSA public key value @math{y = g^x \bmod p}.
@item x-mpi
DSA secret exponent x.
@end table
The public key is similar with "private-key" replaced by "public-key"
and no @var{x-mpi}.
@node ECC key parameters
@subsection ECC key parameters
@anchor{ecc_keyparam}
@noindent
An ECC private key is described by this S-expression:
@example
(private-key
(ecc
(p @var{p-mpi})
(a @var{a-mpi})
(b @var{b-mpi})
(g @var{g-point})
(n @var{n-mpi})
(q @var{q-point})
(d @var{d-mpi})))
@end example
@table @var
@item p-mpi
Prime specifying the field @math{GF(p)}.
@item a-mpi
@itemx b-mpi
The two coefficients of the Weierstrass equation @math{y^2 = x^3 + ax + b}
@item g-point
Base point @math{g}.
@item n-mpi
Order of @math{g}
@item q-point
The point representing the public key @math{Q = dG}.
@item d-mpi
The private key @math{d}
@end table
All point values are encoded in standard format; Libgcrypt does in
general only support uncompressed points, thus the first byte needs to
be @code{0x04}. However ``EdDSA'' describes its own compression
scheme which is used by default; the non-standard first byte
@code{0x40} may optionally be used to explicit flag the use of the
algorithm’s native compression method.
The public key is similar with "private-key" replaced by "public-key"
and no @var{d-mpi}.
If the domain parameters are well-known, the name of this curve may be
used. For example
@example
(private-key
(ecc
(curve "NIST P-192")
(q @var{q-point})
(d @var{d-mpi})))
@end example
Note that @var{q-point} is optional for a private key. The
@code{curve} parameter may be given in any case and is used to replace
missing parameters.
@noindent
Currently implemented curves are:
@table @code
@item NIST P-192
@itemx 1.2.840.10045.3.1.1
@itemx prime192v1
@itemx secp192r1
The NIST 192 bit curve, its OID, X9.62 and SECP aliases.
@item NIST P-224
@itemx secp224r1
The NIST 224 bit curve and its SECP alias.
@item NIST P-256
@itemx 1.2.840.10045.3.1.7
@itemx prime256v1
@itemx secp256r1
The NIST 256 bit curve, its OID, X9.62 and SECP aliases.
@item NIST P-384
@itemx secp384r1
The NIST 384 bit curve and its SECP alias.
@item NIST P-521
@itemx secp521r1
The NIST 521 bit curve and its SECP alias.
@end table
As usual the OIDs may optionally be prefixed with the string @code{OID.}
or @code{oid.}.
@node Cryptographic Functions
@section Cryptographic Functions
@noindent
Some functions operating on S-expressions support `flags' to influence
the operation. These flags have to be listed in a sub-S-expression
named `flags'. Flag names are case-sensitive. The following flags
are known:
@table @code
@item comp
@itemx nocomp
@cindex comp
@cindex nocomp
If supported by the algorithm and curve the @code{comp} flag requests
that points are returned in compact (compressed) representation. The
@code{nocomp} flag requests that points are returned with full
coordinates. The default depends on the the algorithm and curve. The
compact representation requires a small overhead before a point can be
used but halves the size of a to be conveyed public key. If
@code{comp} is used with the ``EdDSA'' algorithm the key generation
prefix the public key with a @code{0x40} byte.
@item pkcs1
@cindex PKCS1
Use PKCS#1 block type 2 padding for encryption, block type 1 padding
for signing.
@item oaep
@cindex OAEP
Use RSA-OAEP padding for encryption.
@item pss
@cindex PSS
Use RSA-PSS padding for signing.
@item eddsa
@cindex EdDSA
Use the EdDSA scheme signing instead of the default ECDSA algorithm.
Note that the EdDSA uses a special form of the public key.
@item rfc6979
@cindex RFC6979
For DSA and ECDSA use a deterministic scheme for the k parameter.
@item no-blinding
@cindex no-blinding
Do not use a technique called `blinding', which is used by default in
order to prevent leaking of secret information. Blinding is only
implemented by RSA, but it might be implemented by other algorithms in
the future as well, when necessary.
@item param
@cindex param
For ECC key generation also return the domain parameters. For ECC
signing and verification override default parameters by provided
domain parameters of the public or private key.
@item transient-key
@cindex transient-key
This flag is only meaningful for RSA, DSA, and ECC key generation. If
given the key is created using a faster and a somewhat less secure
random number generator. This flag may be used for keys which are
only used for a short time or per-message and do not require full
cryptographic strength.
@item no-keytest
@cindex no-keytest
This flag skips internal failsafe tests to assert that a generated key
is properly working. It currently has an effect only for standard ECC
key generation. It is mostly useful along with transient-key to
achieve fastest ECC key generation.
@item use-x931
@cindex X9.31
Force the use of the ANSI X9.31 key generation algorithm instead of
the default algorithm. This flag is only meaningful for RSA key
generation and usually not required. Note that this algorithm is
implicitly used if either @code{derive-parms} is given or Libgcrypt is
in FIPS mode.
@item use-fips186
@cindex FIPS 186
Force the use of the FIPS 186 key generation algorithm instead of the
default algorithm. This flag is only meaningful for DSA and usually
not required. Note that this algorithm is implicitly used if either
@code{derive-parms} is given or Libgcrypt is in FIPS mode. As of now
FIPS 186-2 is implemented; after the approval of FIPS 186-3 the code
will be changed to implement 186-3.
@item use-fips186-2
@cindex FIPS 186-2
Force the use of the FIPS 186-2 key generation algorithm instead of
the default algorithm. This algorithm is slightly different from
FIPS 186-3 and allows only 1024 bit keys. This flag is only meaningful
for DSA and only required for FIPS testing backward compatibility.
@end table
@noindent
Now that we know the key basics, we can carry on and explain how to
encrypt and decrypt data. In almost all cases the data is a random
session key which is in turn used for the actual encryption of the real
data. There are 2 functions to do this:
@deftypefun gcry_error_t gcry_pk_encrypt (@w{gcry_sexp_t *@var{r_ciph},} @w{gcry_sexp_t @var{data},} @w{gcry_sexp_t @var{pkey}})
Obviously a public key must be provided for encryption. It is
expected as an appropriate S-expression (see above) in @var{pkey}.
The data to be encrypted can either be in the simple old format, which
is a very simple S-expression consisting only of one MPI, or it may be
a more complex S-expression which also allows to specify flags for
operation, like e.g. padding rules.
@noindent
If you don't want to let Libgcrypt handle the padding, you must pass an
appropriate MPI using this expression for @var{data}:
@example
(data
(flags raw)
(value @var{mpi}))
@end example
@noindent
This has the same semantics as the old style MPI only way. @var{MPI}
is the actual data, already padded appropriate for your protocol.
Most RSA based systems however use PKCS#1 padding and so you can use
this S-expression for @var{data}:
@example
(data
(flags pkcs1)
(value @var{block}))
@end example
@noindent
Here, the "flags" list has the "pkcs1" flag which let the function know
that it should provide PKCS#1 block type 2 padding. The actual data to
be encrypted is passed as a string of octets in @var{block}. The
function checks that this data actually can be used with the given key,
does the padding and encrypts it.
If the function could successfully perform the encryption, the return
value will be 0 and a new S-expression with the encrypted result is
allocated and assigned to the variable at the address of @var{r_ciph}.
The caller is responsible to release this value using
@code{gcry_sexp_release}. In case of an error, an error code is
returned and @var{r_ciph} will be set to @code{NULL}.
@noindent
The returned S-expression has this format when used with RSA:
@example
(enc-val
(rsa
(a @var{a-mpi})))
@end example
@noindent
Where @var{a-mpi} is an MPI with the result of the RSA operation. When
using the Elgamal algorithm, the return value will have this format:
@example
(enc-val
(elg
(a @var{a-mpi})
(b @var{b-mpi})))
@end example
@noindent
Where @var{a-mpi} and @var{b-mpi} are MPIs with the result of the
Elgamal encryption operation.
@end deftypefun
@c end gcry_pk_encrypt
@deftypefun gcry_error_t gcry_pk_decrypt (@w{gcry_sexp_t *@var{r_plain},} @w{gcry_sexp_t @var{data},} @w{gcry_sexp_t @var{skey}})
Obviously a private key must be provided for decryption. It is expected
as an appropriate S-expression (see above) in @var{skey}. The data to
be decrypted must match the format of the result as returned by
@code{gcry_pk_encrypt}, but should be enlarged with a @code{flags}
element:
@example
(enc-val
(flags)
(elg
(a @var{a-mpi})
(b @var{b-mpi})))
@end example
@noindent
This function does not remove padding from the data by default. To
let Libgcrypt remove padding, give a hint in `flags' telling which
padding method was used when encrypting:
@example
(flags @var{padding-method})
@end example
@noindent
Currently @var{padding-method} is either @code{pkcs1} for PKCS#1 block
type 2 padding, or @code{oaep} for RSA-OAEP padding.
@noindent
The function returns 0 on success or an error code. The variable at the
address of @var{r_plain} will be set to NULL on error or receive the
decrypted value on success. The format of @var{r_plain} is a
simple S-expression part (i.e. not a valid one) with just one MPI if
there was no @code{flags} element in @var{data}; if at least an empty
@code{flags} is passed in @var{data}, the format is:
@example
(value @var{plaintext})
@end example
@end deftypefun
@c end gcry_pk_decrypt
Another operation commonly performed using public key cryptography is
signing data. In some sense this is even more important than
encryption because digital signatures are an important instrument for
key management. Libgcrypt supports digital signatures using
2 functions, similar to the encryption functions:
@deftypefun gcry_error_t gcry_pk_sign (@w{gcry_sexp_t *@var{r_sig},} @w{gcry_sexp_t @var{data},} @w{gcry_sexp_t @var{skey}})
This function creates a digital signature for @var{data} using the
private key @var{skey} and place it into the variable at the address of
@var{r_sig}. @var{data} may either be the simple old style S-expression
with just one MPI or a modern and more versatile S-expression which
allows to let Libgcrypt handle padding:
@example
(data
(flags pkcs1)
(hash @var{hash-algo} @var{block}))
@end example
@noindent
This example requests to sign the data in @var{block} after applying
PKCS#1 block type 1 style padding. @var{hash-algo} is a string with the
hash algorithm to be encoded into the signature, this may be any hash
algorithm name as supported by Libgcrypt. Most likely, this will be
"sha256" or "sha1". It is obvious that the length of @var{block} must
match the size of that message digests; the function checks that this
and other constraints are valid.
@noindent
If PKCS#1 padding is not required (because the caller does already
provide a padded value), either the old format or better the following
format should be used:
@example
(data
(flags raw)
(value @var{mpi}))
@end example
@noindent
Here, the data to be signed is directly given as an @var{MPI}.
@noindent
For DSA the input data is expected in this format:
@example
(data
(flags raw)
(value @var{mpi}))
@end example
@noindent
Here, the data to be signed is directly given as an @var{MPI}. It is
expect that this MPI is the the hash value. For the standard DSA
using a MPI is not a problem in regard to leading zeroes because the
hash value is directly used as an MPI. For better standard
conformance it would be better to explicit use a memory string (like
with pkcs1) but that is currently not supported. However, for
deterministic DSA as specified in RFC6979 this can't be used. Instead
the following input is expected.
@example
(data
(flags rfc6979)
(hash @var{hash-algo} @var{block}))
@end example
Note that the provided hash-algo is used for the internal HMAC; it
should match the hash-algo used to create @var{block}.
@noindent
The signature is returned as a newly allocated S-expression in
@var{r_sig} using this format for RSA:
@example
(sig-val
(rsa
(s @var{s-mpi})))
@end example
Where @var{s-mpi} is the result of the RSA sign operation. For DSA the
S-expression returned is:
@example
(sig-val
(dsa
(r @var{r-mpi})
(s @var{s-mpi})))
@end example
Where @var{r-mpi} and @var{s-mpi} are the result of the DSA sign
operation.
For Elgamal signing (which is slow, yields large numbers and probably
is not as secure as the other algorithms), the same format is used
with "elg" replacing "dsa"; for ECDSA signing, the same format is used
with "ecdsa" replacing "dsa".
For the EdDSA algorithm (cf. Ed25515) the required input parameters are:
@example
(data
(flags eddsa)
(hash-algo sha512)
(value @var{message}))
@end example
Note that the @var{message} may be of any length; hashing is part of
the algorithm. Using a large data block for @var{message} is not
suggested; in that case the used protocol should better require that a
hash of the message is used as input to the EdDSA algorithm.
@end deftypefun
@c end gcry_pk_sign
@noindent
The operation most commonly used is definitely the verification of a
signature. Libgcrypt provides this function:
@deftypefun gcry_error_t gcry_pk_verify (@w{gcry_sexp_t @var{sig}}, @w{gcry_sexp_t @var{data}}, @w{gcry_sexp_t @var{pkey}})
This is used to check whether the signature @var{sig} matches the
@var{data}. The public key @var{pkey} must be provided to perform this
verification. This function is similar in its parameters to
@code{gcry_pk_sign} with the exceptions that the public key is used
instead of the private key and that no signature is created but a
signature, in a format as created by @code{gcry_pk_sign}, is passed to
the function in @var{sig}.
@noindent
The result is 0 for success (i.e. the data matches the signature), or an
error code where the most relevant code is @code{GCRY_ERR_BAD_SIGNATURE}
to indicate that the signature does not match the provided data.
@end deftypefun
@c end gcry_pk_verify
@node General public-key related Functions
@section General public-key related Functions
@noindent
A couple of utility functions are available to retrieve the length of
the key, map algorithm identifiers and perform sanity checks:
@deftypefun {const char *} gcry_pk_algo_name (int @var{algo})
Map the public key algorithm id @var{algo} to a string representation of
the algorithm name. For unknown algorithms this functions returns the
string @code{"?"}. This function should not be used to test for the
availability of an algorithm.
@end deftypefun
@deftypefun int gcry_pk_map_name (const char *@var{name})
Map the algorithm @var{name} to a public key algorithm Id. Returns 0 if
the algorithm name is not known.
@end deftypefun
@deftypefun int gcry_pk_test_algo (int @var{algo})
Return 0 if the public key algorithm @var{algo} is available for use.
Note that this is implemented as a macro.
@end deftypefun
@deftypefun {unsigned int} gcry_pk_get_nbits (gcry_sexp_t @var{key})
Return what is commonly referred as the key length for the given
public or private in @var{key}.
@end deftypefun
@deftypefun {unsigned char *} gcry_pk_get_keygrip (@w{gcry_sexp_t @var{key}}, @w{unsigned char *@var{array}})
Return the so called "keygrip" which is the SHA-1 hash of the public key
parameters expressed in a way depended on the algorithm. @var{array}
must either provide space for 20 bytes or be @code{NULL}. In the latter
case a newly allocated array of that size is returned. On success a
pointer to the newly allocated space or to @var{array} is returned.
@code{NULL} is returned to indicate an error which is most likely an
unknown algorithm or one where a "keygrip" has not yet been defined.
The function accepts public or secret keys in @var{key}.
@end deftypefun
@deftypefun gcry_error_t gcry_pk_testkey (gcry_sexp_t @var{key})
Return zero if the private key @var{key} is `sane', an error code otherwise.
Note that it is not possible to check the `saneness' of a public key.
@end deftypefun
@deftypefun gcry_error_t gcry_pk_algo_info (@w{int @var{algo}}, @w{int @var{what}}, @w{void *@var{buffer}}, @w{size_t *@var{nbytes}})
Depending on the value of @var{what} return various information about
the public key algorithm with the id @var{algo}. Note that the
function returns @code{-1} on error and the actual error code must be
retrieved using the function @code{gcry_errno}. The currently defined
values for @var{what} are:
@table @code
@item GCRYCTL_TEST_ALGO:
Return 0 if the specified algorithm is available for use.
@var{buffer} must be @code{NULL}, @var{nbytes} may be passed as
@code{NULL} or point to a variable with the required usage of the
algorithm. This may be 0 for "don't care" or the bit-wise OR of these
flags:
@table @code
@item GCRY_PK_USAGE_SIGN
Algorithm is usable for signing.
@item GCRY_PK_USAGE_ENCR
Algorithm is usable for encryption.
@end table
Unless you need to test for the allowed usage, it is in general better
to use the macro gcry_pk_test_algo instead.
@item GCRYCTL_GET_ALGO_USAGE:
Return the usage flags for the given algorithm. An invalid algorithm
return 0. Disabled algorithms are ignored here because we
want to know whether the algorithm is at all capable of a certain usage.
@item GCRYCTL_GET_ALGO_NPKEY
Return the number of elements the public key for algorithm @var{algo}
consist of. Return 0 for an unknown algorithm.
@item GCRYCTL_GET_ALGO_NSKEY
Return the number of elements the private key for algorithm @var{algo}
consist of. Note that this value is always larger than that of the
public key. Return 0 for an unknown algorithm.
@item GCRYCTL_GET_ALGO_NSIGN
Return the number of elements a signature created with the algorithm
@var{algo} consists of. Return 0 for an unknown algorithm or for an
algorithm not capable of creating signatures.
@item GCRYCTL_GET_ALGO_NENC
Return the number of elements a encrypted message created with the algorithm
@var{algo} consists of. Return 0 for an unknown algorithm or for an
algorithm not capable of encryption.
@end table
@noindent
Please note that parameters not required should be passed as @code{NULL}.
@end deftypefun
@c end gcry_pk_algo_info
@deftypefun gcry_error_t gcry_pk_ctl (@w{int @var{cmd}}, @w{void *@var{buffer}}, @w{size_t @var{buflen}})
This is a general purpose function to perform certain control
operations. @var{cmd} controls what is to be done. The return value is
0 for success or an error code. Currently supported values for
@var{cmd} are:
@table @code
@item GCRYCTL_DISABLE_ALGO
Disable the algorithm given as an algorithm id in @var{buffer}.
@var{buffer} must point to an @code{int} variable with the algorithm
id and @var{buflen} must have the value @code{sizeof (int)}. This
function is not thread safe and should thus be used before any other
threads are started.
@end table
@end deftypefun
@c end gcry_pk_ctl
@noindent
Libgcrypt also provides a function to generate public key
pairs:
@deftypefun gcry_error_t gcry_pk_genkey (@w{gcry_sexp_t *@var{r_key}}, @w{gcry_sexp_t @var{parms}})
This function create a new public key pair using information given in
the S-expression @var{parms} and stores the private and the public key
in one new S-expression at the address given by @var{r_key}. In case of
an error, @var{r_key} is set to @code{NULL}. The return code is 0 for
success or an error code otherwise.
@noindent
Here is an example for @var{parms} to create an 2048 bit RSA key:
@example
(genkey
(rsa
(nbits 4:2048)))
@end example
@noindent
To create an Elgamal key, substitute "elg" for "rsa" and to create a DSA
key use "dsa". Valid ranges for the key length depend on the
algorithms; all commonly used key lengths are supported. Currently
supported parameters are:
@table @code
@item nbits
This is always required to specify the length of the key. The
argument is a string with a number in C-notation. The value should be
a multiple of 8. Note that the S-expression syntax requires that a
number is prefixed with its string length; thus the @code{4:} in the
above example.
@item curve @var{name}
For ECC a named curve may be used instead of giving the number of
requested bits. This allows to request a specific curve to override a
default selection Libgcrypt would have taken if @code{nbits} has been
given. The available names are listed with the description of the ECC
public key parameters.
@item rsa-use-e @var{value}
This is only used with RSA to give a hint for the public exponent. The
@var{value} will be used as a base to test for a usable exponent. Some
values are special:
@table @samp
@item 0
Use a secure and fast value. This is currently the number 41.
@item 1
Use a value as required by some crypto policies. This is currently
the number 65537.
@item 2
Reserved
@item > 2
Use the given value.
@end table
@noindent
If this parameter is not used, Libgcrypt uses for historic reasons
65537.
@item qbits @var{n}
This is only meanigful for DSA keys. If it is given the DSA key is
generated with a Q parameyer of size @var{n} bits. If it is not given
or zero Q is deduced from NBITS in this way:
@table @samp
@item 512 <= N <= 1024
Q = 160
@item N = 2048
Q = 224
@item N = 3072
Q = 256
@item N = 7680
Q = 384
@item N = 15360
Q = 512
@end table
Note that in this case only the values for N, as given in the table,
are allowed. When specifying Q all values of N in the range 512 to
15680 are valid as long as they are multiples of 8.
@item domain @var{list}
This is only meaningful for DLP algorithms. If specified keys are
generated with domain parameters taken from this list. The exact
format of this parameter depends on the actual algorithm. It is
currently only implemented for DSA using this format:
@example
(genkey
(dsa
(domain
(p @var{p-mpi})
(q @var{q-mpi})
(g @var{q-mpi}))))
@end example
@code{nbits} and @code{qbits} may not be specified because they are
derived from the domain parameters.
@item derive-parms @var{list}
This is currently only implemented for RSA and DSA keys. It is not
allowed to use this together with a @code{domain} specification. If
given, it is used to derive the keys using the given parameters.
If given for an RSA key the X9.31 key generation algorithm is used
even if libgcrypt is not in FIPS mode. If given for a DSA key, the
FIPS 186 algorithm is used even if libgcrypt is not in FIPS mode.
@example
(genkey
(rsa
(nbits 4:1024)
(rsa-use-e 1:3)
(derive-parms
(Xp1 #1A1916DDB29B4EB7EB6732E128#)
(Xp2 #192E8AAC41C576C822D93EA433#)
(Xp #D8CD81F035EC57EFE822955149D3BFF70C53520D
769D6D76646C7A792E16EBD89FE6FC5B605A6493
39DFC925A86A4C6D150B71B9EEA02D68885F5009
B98BD984#)
(Xq1 #1A5CF72EE770DE50CB09ACCEA9#)
(Xq2 #134E4CAA16D2350A21D775C404#)
(Xq #CC1092495D867E64065DEE3E7955F2EBC7D47A2D
7C9953388F97DDDC3E1CA19C35CA659EDC2FC325
6D29C2627479C086A699A49C4C9CEE7EF7BD1B34
321DE34A#))))
@end example
@example
(genkey
(dsa
(nbits 4:1024)
(derive-parms
(seed @var{seed-mpi}))))
@end example
@item flags @var{flaglist}
This is preferred way to define flags. @var{flaglist} may contain any
number of flags. See above for a specification of these flags.
Here is an example on how to create a key using curve Ed25519 with the
ECDSA signature algorithm. Note that the use of ECDSA with that curve
is in general not recommended.
@example
(genkey
(ecc
(flags transient-key)))
@end example
@item transient-key
@itemx use-x931
@itemx use-fips186
@itemx use-fips186-2
These are deprecated ways to set a flag with that name; see above for
a description of each flag.
@end table
@c end table of parameters
@noindent
The key pair is returned in a format depending on the algorithm. Both
private and public keys are returned in one container and may be
accompanied by some miscellaneous information.
@noindent
Here are two examples; the first for Elgamal and the second for
elliptic curve key generation:
@example
(key-data
(public-key
(elg
(p @var{p-mpi})
(g @var{g-mpi})
(y @var{y-mpi})))
(private-key
(elg
(p @var{p-mpi})
(g @var{g-mpi})
(y @var{y-mpi})
(x @var{x-mpi})))
(misc-key-info
(pm1-factors @var{n1 n2 ... nn}))
@end example
@example
(key-data
(public-key
(ecc
(curve Ed25519)
(flags eddsa)
(q @var{q-value})))
(private-key
(ecc
(curve Ed25519)
(flags eddsa)
(q @var{q-value})
(d @var{d-value}))))
@end example
@noindent
As you can see, some of the information is duplicated, but this
provides an easy way to extract either the public or the private key.
Note that the order of the elements is not defined, e.g. the private
key may be stored before the public key. @var{n1 n2 ... nn} is a list
of prime numbers used to composite @var{p-mpi}; this is in general not
a very useful information and only available if the key generation
algorithm provides them.
@end deftypefun
@c end gcry_pk_genkey
@noindent
Future versions of Libgcrypt will have extended versions of the public
key interfaced which will take an additional context to allow for
pre-computations, special operations, and other optimization. As a
first step a new function is introduced to help using the ECC
algorithms in new ways:
@deftypefun gcry_error_t gcry_pubkey_get_sexp (@w{gcry_sexp_t *@var{r_sexp}}, @
@w{int @var{mode}}, @w{gcry_ctx_t @var{ctx}})
Return an S-expression representing the context @var{ctx}. Depending
on the state of that context, the S-expression may either be a public
key, a private key or any other object used with public key
operations. On success 0 is returned and a new S-expression is stored
at @var{r_sexp}; on error an error code is returned and NULL is stored
at @var{r_sexp}. @var{mode} must be one of:
@table @code
@item 0
Decide what to return depending on the context. For example if the
private key parameter is available a private key is returned, if not a
public key is returned.
@item GCRY_PK_GET_PUBKEY
Return the public key even if the context has the private key
parameter.
@item GCRY_PK_GET_SECKEY
Return the private key or the error @code{GPG_ERR_NO_SECKEY} if it is
not possible.
@end table
As of now this function supports only certain ECC operations because a
context object is right now only defined for ECC. Over time this
function will be extended to cover more algorithms.
@end deftypefun
@c end gcry_pubkey_get_sexp
@c **********************************************************
@c ******************* Hash Functions *********************
@c **********************************************************
@node Hashing
@chapter Hashing
Libgcrypt provides an easy and consistent to use interface for hashing.
Hashing is buffered and several hash algorithms can be updated at once.
It is possible to compute a HMAC using the same routines. The
programming model follows an open/process/close paradigm and is in that
similar to other building blocks provided by Libgcrypt.
For convenience reasons, a few cyclic redundancy check value operations
are also supported.
@menu
* Available hash algorithms:: List of hash algorithms supported by the library.
* Working with hash algorithms:: List of functions related to hashing.
@end menu
@node Available hash algorithms
@section Available hash algorithms
@c begin table of hash algorithms
@cindex SHA-1
@cindex SHA-224, SHA-256, SHA-384, SHA-512
@cindex SHA3-224, SHA3-256, SHA3-384, SHA3-512, SHAKE128, SHAKE256
@cindex RIPE-MD-160
@cindex MD2, MD4, MD5
@cindex TIGER, TIGER1, TIGER2
@cindex HAVAL
@cindex Whirlpool
@cindex BLAKE2b-512, BLAKE2b-384, BLAKE2b-256, BLAKE2b-160
@cindex BLAKE2s-256, BLAKE2s-224, BLAKE2s-160, BLAKE2s-128
@cindex CRC32
@table @code
@item GCRY_MD_NONE
This is not a real algorithm but used by some functions as an error
return value. This constant is guaranteed to have the value @code{0}.
@item GCRY_MD_SHA1
This is the SHA-1 algorithm which yields a message digest of 20 bytes.
Note that SHA-1 begins to show some weaknesses and it is suggested to
fade out its use if strong cryptographic properties are required.
@item GCRY_MD_RMD160
This is the 160 bit version of the RIPE message digest (RIPE-MD-160).
Like SHA-1 it also yields a digest of 20 bytes. This algorithm share a
lot of design properties with SHA-1 and thus it is advisable not to use
it for new protocols.
@item GCRY_MD_MD5
This is the well known MD5 algorithm, which yields a message digest of
16 bytes. Note that the MD5 algorithm has severe weaknesses, for
example it is easy to compute two messages yielding the same hash
(collision attack). The use of this algorithm is only justified for
non-cryptographic application.
@item GCRY_MD_MD4
This is the MD4 algorithm, which yields a message digest of 16 bytes.
This algorithm has severe weaknesses and should not be used.
@item GCRY_MD_MD2
This is an reserved identifier for MD-2; there is no implementation yet.
This algorithm has severe weaknesses and should not be used.
@item GCRY_MD_TIGER
This is the TIGER/192 algorithm which yields a message digest of 24
bytes. Actually this is a variant of TIGER with a different output
print order as used by GnuPG up to version 1.3.2.
@item GCRY_MD_TIGER1
This is the TIGER variant as used by the NESSIE project. It uses the
most commonly used output print order.
@item GCRY_MD_TIGER2
This is another variant of TIGER with a different padding scheme.
@item GCRY_MD_HAVAL
This is an reserved value for the HAVAL algorithm with 5 passes and 160
bit. It yields a message digest of 20 bytes. Note that there is no
implementation yet available.
@item GCRY_MD_SHA224
This is the SHA-224 algorithm which yields a message digest of 28 bytes.
See Change Notice 1 for FIPS 180-2 for the specification.
@item GCRY_MD_SHA256
This is the SHA-256 algorithm which yields a message digest of 32 bytes.
See FIPS 180-2 for the specification.
@item GCRY_MD_SHA384
This is the SHA-384 algorithm which yields a message digest of 48 bytes.
See FIPS 180-2 for the specification.
@item GCRY_MD_SHA512
This is the SHA-384 algorithm which yields a message digest of 64 bytes.
See FIPS 180-2 for the specification.
@item GCRY_MD_SHA3_224
This is the SHA3-224 algorithm which yields a message digest of 28 bytes.
See FIPS 202 for the specification.
@item GCRY_MD_SHA3_256
This is the SHA3-256 algorithm which yields a message digest of 32 bytes.
See FIPS 202 for the specification.
@item GCRY_MD_SHA3_384
This is the SHA3-384 algorithm which yields a message digest of 48 bytes.
See FIPS 202 for the specification.
@item GCRY_MD_SHA3_512
This is the SHA3-384 algorithm which yields a message digest of 64 bytes.
See FIPS 202 for the specification.
@item GCRY_MD_SHAKE128
This is the SHAKE128 extendable-output function (XOF) algorithm with 128 bit
security strength.
See FIPS 202 for the specification.
@item GCRY_MD_SHAKE256
This is the SHAKE256 extendable-output function (XOF) algorithm with 256 bit
security strength.
See FIPS 202 for the specification.
@item GCRY_MD_CRC32
This is the ISO 3309 and ITU-T V.42 cyclic redundancy check. It yields
an output of 4 bytes. Note that this is not a hash algorithm in the
cryptographic sense.
@item GCRY_MD_CRC32_RFC1510
This is the above cyclic redundancy check function, as modified by RFC
1510. It yields an output of 4 bytes. Note that this is not a hash
algorithm in the cryptographic sense.
@item GCRY_MD_CRC24_RFC2440
This is the OpenPGP cyclic redundancy check function. It yields an
output of 3 bytes. Note that this is not a hash algorithm in the
cryptographic sense.
@item GCRY_MD_WHIRLPOOL
This is the Whirlpool algorithm which yields a message digest of 64
bytes.
@item GCRY_MD_GOSTR3411_94
This is the hash algorithm described in GOST R 34.11-94 which yields a
message digest of 32 bytes.
@item GCRY_MD_STRIBOG256
This is the 256-bit version of hash algorithm described in GOST R 34.11-2012
which yields a message digest of 32 bytes.
@item GCRY_MD_STRIBOG512
This is the 512-bit version of hash algorithm described in GOST R 34.11-2012
which yields a message digest of 64 bytes.
@item GCRY_MD_BLAKE2B_512
This is the BLAKE2b-512 algorithm which yields a message digest of 64 bytes.
See RFC 7693 for the specification.
@item GCRY_MD_BLAKE2B_384
This is the BLAKE2b-384 algorithm which yields a message digest of 48 bytes.
See RFC 7693 for the specification.
@item GCRY_MD_BLAKE2B_256
This is the BLAKE2b-256 algorithm which yields a message digest of 32 bytes.
See RFC 7693 for the specification.
@item GCRY_MD_BLAKE2B_160
This is the BLAKE2b-160 algorithm which yields a message digest of 20 bytes.
See RFC 7693 for the specification.
@item GCRY_MD_BLAKE2S_256
This is the BLAKE2s-256 algorithm which yields a message digest of 32 bytes.
See RFC 7693 for the specification.
@item GCRY_MD_BLAKE2S_224
This is the BLAKE2s-224 algorithm which yields a message digest of 28 bytes.
See RFC 7693 for the specification.
@item GCRY_MD_BLAKE2S_160
This is the BLAKE2s-160 algorithm which yields a message digest of 20 bytes.
See RFC 7693 for the specification.
@item GCRY_MD_BLAKE2S_128
This is the BLAKE2s-128 algorithm which yields a message digest of 16 bytes.
See RFC 7693 for the specification.
@end table
@c end table of hash algorithms
@node Working with hash algorithms
@section Working with hash algorithms
To use most of these function it is necessary to create a context;
this is done using:
@deftypefun gcry_error_t gcry_md_open (gcry_md_hd_t *@var{hd}, int @var{algo}, unsigned int @var{flags})
Create a message digest object for algorithm @var{algo}. @var{flags}
may be given as an bitwise OR of constants described below. @var{algo}
may be given as @code{0} if the algorithms to use are later set using
@code{gcry_md_enable}. @var{hd} is guaranteed to either receive a valid
handle or NULL.
For a list of supported algorithms, see @xref{Available hash
algorithms}.
The flags allowed for @var{mode} are:
@c begin table of hash flags
@table @code
@item GCRY_MD_FLAG_SECURE
Allocate all buffers and the resulting digest in "secure memory". Use
this is the hashed data is highly confidential.
@item GCRY_MD_FLAG_HMAC
@cindex HMAC
Turn the algorithm into a HMAC message authentication algorithm. This
only works if just one algorithm is enabled for the handle and that
algorithm is not an extendable-output function. Note that the function
@code{gcry_md_setkey} must be used to set the MAC key. The size of the
MAC is equal to the message digest of the underlying hash algorithm.
If you want CBC message authentication codes based on a cipher,
see @xref{Working with cipher handles}.
@item GCRY_MD_FLAG_BUGEMU1
@cindex bug emulation
Versions of Libgcrypt before 1.6.0 had a bug in the Whirlpool code
which led to a wrong result for certain input sizes and write
patterns. Using this flag emulates that bug. This may for example be
useful for applications which use Whirlpool as part of their key
generation. It is strongly suggested to use this flag only if really
needed and if possible to the data should be re-processed using the
regular Whirlpool algorithm.
Note that this flag works for the entire hash context. If needed
arises it may be used to enable bug emulation for other hash
algorithms. Thus you should not use this flag for a multi-algorithm
hash context.
@end table
@c begin table of hash flags
You may use the function @code{gcry_md_is_enabled} to later check
whether an algorithm has been enabled.
@end deftypefun
@c end function gcry_md_open
If you want to calculate several hash algorithms at the same time, you
have to use the following function right after the @code{gcry_md_open}:
@deftypefun gcry_error_t gcry_md_enable (gcry_md_hd_t @var{h}, int @var{algo})
Add the message digest algorithm @var{algo} to the digest object
described by handle @var{h}. Duplicated enabling of algorithms is
detected and ignored.
@end deftypefun
If the flag @code{GCRY_MD_FLAG_HMAC} was used, the key for the MAC must
be set using the function:
@deftypefun gcry_error_t gcry_md_setkey (gcry_md_hd_t @var{h}, const void *@var{key}, size_t @var{keylen})
For use with the HMAC feature or BLAKE2 keyed hash, set the MAC key to
the value of @var{key} of length @var{keylen} bytes. For HMAC, there
is no restriction on the length of the key. For keyed BLAKE2b hash,
length of the key must be 64 bytes or less. For keyed BLAKE2s hash,
length of the key must be 32 bytes or less.
@end deftypefun
After you are done with the hash calculation, you should release the
resources by using:
@deftypefun void gcry_md_close (gcry_md_hd_t @var{h})
Release all resources of hash context @var{h}. @var{h} should not be
used after a call to this function. A @code{NULL} passed as @var{h} is
ignored. The function also zeroises all sensitive information
associated with this handle.
@end deftypefun
Often you have to do several hash operations using the same algorithm.
To avoid the overhead of creating and releasing context, a reset function
is provided:
@deftypefun void gcry_md_reset (gcry_md_hd_t @var{h})
Reset the current context to its initial state. This is effectively
identical to a close followed by an open and enabling all currently
active algorithms.
@end deftypefun
Often it is necessary to start hashing some data and then continue to
hash different data. To avoid hashing the same data several times (which
might not even be possible if the data is received from a pipe), a
snapshot of the current hash context can be taken and turned into a new
context:
@deftypefun gcry_error_t gcry_md_copy (gcry_md_hd_t *@var{handle_dst}, gcry_md_hd_t @var{handle_src})
Create a new digest object as an exact copy of the object described by
handle @var{handle_src} and store it in @var{handle_dst}. The context
is not reset and you can continue to hash data using this context and
independently using the original context.
@end deftypefun
Now that we have prepared everything to calculate hashes, it is time to
see how it is actually done. There are two ways for this, one to
update the hash with a block of memory and one macro to update the hash
by just one character. Both methods can be used on the same hash context.
@deftypefun void gcry_md_write (gcry_md_hd_t @var{h}, const void *@var{buffer}, size_t @var{length})
Pass @var{length} bytes of the data in @var{buffer} to the digest object
with handle @var{h} to update the digest values. This
function should be used for large blocks of data. If this function is
used after the context has been finalized, it will keep on pushing
the data through the algorithm specific transform function and change
the context; however the results are not meaningful and this feature
is only available to mitigate timing attacks.
@end deftypefun
@deftypefun void gcry_md_putc (gcry_md_hd_t @var{h}, int @var{c})
Pass the byte in @var{c} to the digest object with handle @var{h} to
update the digest value. This is an efficient function, implemented as
a macro to buffer the data before an actual update.
@end deftypefun
The semantics of the hash functions do not provide for reading out intermediate
message digests because the calculation must be finalized first. This
finalization may for example include the number of bytes hashed in the
message digest or some padding.
@deftypefun void gcry_md_final (gcry_md_hd_t @var{h})
Finalize the message digest calculation. This is not really needed
because @code{gcry_md_read} and @code{gcry_md_extract} do this implicitly.
After this has been done no further updates (by means of @code{gcry_md_write}
or @code{gcry_md_putc} should be done; However, to mitigate timing
attacks it is sometimes useful to keep on updating the context after
having stored away the actual digest. Only the first call to this function
has an effect. It is implemented as a macro.
@end deftypefun
The way to read out the calculated message digest is by using the
function:
@deftypefun {unsigned char *} gcry_md_read (gcry_md_hd_t @var{h}, int @var{algo})
@code{gcry_md_read} returns the message digest after finalizing the
calculation. This function may be used as often as required but it will
always return the same value for one handle. The returned message digest
is allocated within the message context and therefore valid until the
handle is released or reset-ed (using @code{gcry_md_close} or
@code{gcry_md_reset} or it has been updated as a mitigation measure
against timing attacks. @var{algo} may be given as 0 to return the only
enabled message digest or it may specify one of the enabled algorithms.
The function does return @code{NULL} if the requested algorithm has not
been enabled.
@end deftypefun
The way to read output of extendable-output function is by using the
function:
@deftypefun gpg_err_code_t gcry_md_extract (gcry_md_hd_t @var{h}, @
int @var{algo}, void *@var{buffer}, size_t @var{length})
@code{gcry_mac_read} returns output from extendable-output function.
This function may be used as often as required to generate more output
byte stream from the algorithm. Function extracts the new output bytes
to @var{buffer} of the length @var{length}. Buffer will be fully
populated with new output. @var{algo} may be given as 0 to return the only
enabled message digest or it may specify one of the enabled algorithms.
The function does return non-zero value if the requested algorithm has not
been enabled.
@end deftypefun
Because it is often necessary to get the message digest of blocks of
memory, two fast convenience function are available for this task:
@deftypefun gpg_err_code_t gcry_md_hash_buffers ( @
@w{int @var{algo}}, @w{unsigned int @var{flags}}, @
@w{void *@var{digest}}, @
@w{const gcry_buffer_t *@var{iov}}, @w{int @var{iovcnt}} )
@code{gcry_md_hash_buffers} is a shortcut function to calculate a
message digest from several buffers. This function does not require a
context and immediately returns the message digest of the data
described by @var{iov} and @var{iovcnt}. @var{digest} must be
allocated by the caller, large enough to hold the message digest
yielded by the the specified algorithm @var{algo}. This required size
may be obtained by using the function @code{gcry_md_get_algo_dlen}.
@var{iov} is an array of buffer descriptions with @var{iovcnt} items.
The caller should zero out the structures in this array and for each
array item set the fields @code{.data} to the address of the data to
be hashed, @code{.len} to number of bytes to be hashed. If @var{.off}
is also set, the data is taken starting at @var{.off} bytes from the
begin of the buffer. The field @code{.size} is not used.
The only supported flag value for @var{flags} is
@var{GCRY_MD_FLAG_HMAC} which turns this function into a HMAC
function; the first item in @var{iov} is then used as the key.
On success the function returns 0 and stores the resulting hash or MAC
at @var{digest}.
@end deftypefun
@deftypefun void gcry_md_hash_buffer (int @var{algo}, void *@var{digest}, const void *@var{buffer}, size_t @var{length});
@code{gcry_md_hash_buffer} is a shortcut function to calculate a message
digest of a buffer. This function does not require a context and
immediately returns the message digest of the @var{length} bytes at
@var{buffer}. @var{digest} must be allocated by the caller, large
enough to hold the message digest yielded by the the specified algorithm
@var{algo}. This required size may be obtained by using the function
@code{gcry_md_get_algo_dlen}.
Note that in contrast to @code{gcry_md_hash_buffers} this function
will abort the process if an unavailable algorithm is used.
@end deftypefun
@c ***********************************
@c ***** MD info functions ***********
@c ***********************************
Hash algorithms are identified by internal algorithm numbers (see
@code{gcry_md_open} for a list). However, in most applications they are
used by names, so two functions are available to map between string
representations and hash algorithm identifiers.
@deftypefun {const char *} gcry_md_algo_name (int @var{algo})
Map the digest algorithm id @var{algo} to a string representation of the
algorithm name. For unknown algorithms this function returns the
string @code{"?"}. This function should not be used to test for the
availability of an algorithm.
@end deftypefun
@deftypefun int gcry_md_map_name (const char *@var{name})
Map the algorithm with @var{name} to a digest algorithm identifier.
Returns 0 if the algorithm name is not known. Names representing
@acronym{ASN.1} object identifiers are recognized if the @acronym{IETF}
dotted format is used and the OID is prefixed with either "@code{oid.}"
or "@code{OID.}". For a list of supported OIDs, see the source code at
@file{cipher/md.c}. This function should not be used to test for the
availability of an algorithm.
@end deftypefun
@deftypefun gcry_error_t gcry_md_get_asnoid (int @var{algo}, void *@var{buffer}, size_t *@var{length})
Return an DER encoded ASN.1 OID for the algorithm @var{algo} in the
user allocated @var{buffer}. @var{length} must point to variable with
the available size of @var{buffer} and receives after return the
actual size of the returned OID. The returned error code may be
@code{GPG_ERR_TOO_SHORT} if the provided buffer is to short to receive
the OID; it is possible to call the function with @code{NULL} for
@var{buffer} to have it only return the required size. The function
returns 0 on success.
@end deftypefun
To test whether an algorithm is actually available for use, the
following macro should be used:
@deftypefun gcry_error_t gcry_md_test_algo (int @var{algo})
The macro returns 0 if the algorithm @var{algo} is available for use.
@end deftypefun
If the length of a message digest is not known, it can be retrieved
using the following function:
@deftypefun {unsigned int} gcry_md_get_algo_dlen (int @var{algo})
Retrieve the length in bytes of the digest yielded by algorithm
@var{algo}. This is often used prior to @code{gcry_md_read} to allocate
sufficient memory for the digest.
@end deftypefun
In some situations it might be hard to remember the algorithm used for
the ongoing hashing. The following function might be used to get that
information:
@deftypefun int gcry_md_get_algo (gcry_md_hd_t @var{h})
Retrieve the algorithm used with the handle @var{h}. Note that this
does not work reliable if more than one algorithm is enabled in @var{h}.
@end deftypefun
The following macro might also be useful:
@deftypefun int gcry_md_is_secure (gcry_md_hd_t @var{h})
This function returns true when the digest object @var{h} is allocated
in "secure memory"; i.e. @var{h} was created with the
@code{GCRY_MD_FLAG_SECURE}.
@end deftypefun
@deftypefun int gcry_md_is_enabled (gcry_md_hd_t @var{h}, int @var{algo})
This function returns true when the algorithm @var{algo} has been
enabled for the digest object @var{h}.
@end deftypefun
Tracking bugs related to hashing is often a cumbersome task which
requires to add a lot of printf statements into the code.
Libgcrypt provides an easy way to avoid this. The actual data
hashed can be written to files on request.
@deftypefun void gcry_md_debug (gcry_md_hd_t @var{h}, const char *@var{suffix})
Enable debugging for the digest object with handle @var{h}. This
creates files named @file{dbgmd-<n>.<string>} while doing the
actual hashing. @var{suffix} is the string part in the filename. The
number is a counter incremented for each new hashing. The data in the
file is the raw data as passed to @code{gcry_md_write} or
@code{gcry_md_putc}. If @code{NULL} is used for @var{suffix}, the
debugging is stopped and the file closed. This is only rarely required
because @code{gcry_md_close} implicitly stops debugging.
@end deftypefun
@c **********************************************************
@c ******************* MAC Functions **********************
@c **********************************************************
@node Message Authentication Codes
@chapter Message Authentication Codes
Libgcrypt provides an easy and consistent to use interface for generating
Message Authentication Codes (MAC). MAC generation is buffered and interface
similar to the one used with hash algorithms. The programming model follows
an open/process/close paradigm and is in that similar to other building blocks
provided by Libgcrypt.
@menu
* Available MAC algorithms:: List of MAC algorithms supported by the library.
* Working with MAC algorithms:: List of functions related to MAC algorithms.
@end menu
@node Available MAC algorithms
@section Available MAC algorithms
@c begin table of MAC algorithms
@cindex HMAC-SHA-1
@cindex HMAC-SHA-224, HMAC-SHA-256, HMAC-SHA-384, HMAC-SHA-512
@cindex HMAC-SHA3-224, HMAC-SHA3-256, HMAC-SHA3-384, HMAC-SHA3-512
@cindex HMAC-RIPE-MD-160
@cindex HMAC-MD2, HMAC-MD4, HMAC-MD5
@cindex HMAC-TIGER1
@cindex HMAC-Whirlpool
@cindex HMAC-Stribog-256, HMAC-Stribog-512
@cindex HMAC-GOSTR-3411-94
@table @code
@item GCRY_MAC_NONE
This is not a real algorithm but used by some functions as an error
return value. This constant is guaranteed to have the value @code{0}.
@item GCRY_MAC_HMAC_SHA256
This is keyed-hash message authentication code (HMAC) message authentication
algorithm based on the SHA-256 hash algorithm.
@item GCRY_MAC_HMAC_SHA224
This is HMAC message authentication algorithm based on the SHA-224 hash
algorithm.
@item GCRY_MAC_HMAC_SHA512
This is HMAC message authentication algorithm based on the SHA-512 hash
algorithm.
@item GCRY_MAC_HMAC_SHA384
This is HMAC message authentication algorithm based on the SHA-384 hash
algorithm.
@item GCRY_MAC_HMAC_SHA3_256
This is HMAC message authentication algorithm based on the SHA3-384 hash
algorithm.
@item GCRY_MAC_HMAC_SHA3_224
This is HMAC message authentication algorithm based on the SHA3-224 hash
algorithm.
@item GCRY_MAC_HMAC_SHA3_512
This is HMAC message authentication algorithm based on the SHA3-512 hash
algorithm.
@item GCRY_MAC_HMAC_SHA3_384
This is HMAC message authentication algorithm based on the SHA3-384 hash
algorithm.
@item GCRY_MAC_HMAC_SHA1
This is HMAC message authentication algorithm based on the SHA-1 hash
algorithm.
@item GCRY_MAC_HMAC_MD5
This is HMAC message authentication algorithm based on the MD5 hash
algorithm.
@item GCRY_MAC_HMAC_MD4
This is HMAC message authentication algorithm based on the MD4 hash
algorithm.
@item GCRY_MAC_HMAC_RMD160
This is HMAC message authentication algorithm based on the RIPE-MD-160 hash
algorithm.
@item GCRY_MAC_HMAC_WHIRLPOOL
This is HMAC message authentication algorithm based on the WHIRLPOOL hash
algorithm.
@item GCRY_MAC_HMAC_GOSTR3411_94
This is HMAC message authentication algorithm based on the GOST R 34.11-94 hash
algorithm.
@item GCRY_MAC_HMAC_STRIBOG256
This is HMAC message authentication algorithm based on the 256-bit hash
algorithm described in GOST R 34.11-2012.
@item GCRY_MAC_HMAC_STRIBOG512
This is HMAC message authentication algorithm based on the 512-bit hash
algorithm described in GOST R 34.11-2012.
@item GCRY_MAC_CMAC_AES
This is CMAC (Cipher-based MAC) message authentication algorithm based on
the AES block cipher algorithm.
@item GCRY_MAC_CMAC_3DES
This is CMAC message authentication algorithm based on the three-key EDE
Triple-DES block cipher algorithm.
@item GCRY_MAC_CMAC_CAMELLIA
This is CMAC message authentication algorithm based on the Camellia block cipher
algorithm.
@item GCRY_MAC_CMAC_CAST5
This is CMAC message authentication algorithm based on the CAST128-5
block cipher algorithm.
@item GCRY_MAC_CMAC_BLOWFISH
This is CMAC message authentication algorithm based on the Blowfish
block cipher algorithm.
@item GCRY_MAC_CMAC_TWOFISH
This is CMAC message authentication algorithm based on the Twofish
block cipher algorithm.
@item GCRY_MAC_CMAC_SERPENT
This is CMAC message authentication algorithm based on the Serpent
block cipher algorithm.
@item GCRY_MAC_CMAC_SEED
This is CMAC message authentication algorithm based on the SEED
block cipher algorithm.
@item GCRY_MAC_CMAC_RFC2268
This is CMAC message authentication algorithm based on the Ron's Cipher 2
block cipher algorithm.
@item GCRY_MAC_CMAC_IDEA
This is CMAC message authentication algorithm based on the IDEA
block cipher algorithm.
@item GCRY_MAC_CMAC_GOST28147
This is CMAC message authentication algorithm based on the GOST 28147-89
block cipher algorithm.
@item GCRY_MAC_GMAC_AES
This is GMAC (GCM mode based MAC) message authentication algorithm based on
the AES block cipher algorithm.
@item GCRY_MAC_GMAC_CAMELLIA
This is GMAC message authentication algorithm based on the Camellia
block cipher algorithm.
@item GCRY_MAC_GMAC_TWOFISH
This is GMAC message authentication algorithm based on the Twofish
block cipher algorithm.
@item GCRY_MAC_GMAC_SERPENT
This is GMAC message authentication algorithm based on the Serpent
block cipher algorithm.
@item GCRY_MAC_GMAC_SEED
This is GMAC message authentication algorithm based on the SEED
block cipher algorithm.
@item GCRY_MAC_POLY1305
This is plain Poly1305 message authentication algorithm, used with
one-time key.
@item GCRY_MAC_POLY1305_AES
This is Poly1305-AES message authentication algorithm, used with
key and one-time nonce.
@item GCRY_MAC_POLY1305_CAMELLIA
This is Poly1305-Camellia message authentication algorithm, used with
key and one-time nonce.
@item GCRY_MAC_POLY1305_TWOFISH
This is Poly1305-Twofish message authentication algorithm, used with
key and one-time nonce.
@item GCRY_MAC_POLY1305_SERPENT
This is Poly1305-Serpent message authentication algorithm, used with
key and one-time nonce.
@item GCRY_MAC_POLY1305_SEED
This is Poly1305-SEED message authentication algorithm, used with
key and one-time nonce.
@end table
@c end table of MAC algorithms
@node Working with MAC algorithms
@section Working with MAC algorithms
To use most of these function it is necessary to create a context;
this is done using:
@deftypefun gcry_error_t gcry_mac_open (gcry_mac_hd_t *@var{hd}, int @var{algo}, unsigned int @var{flags}, gcry_ctx_t @var{ctx})
Create a MAC object for algorithm @var{algo}. @var{flags} may be given as an
bitwise OR of constants described below. @var{hd} is guaranteed to either
receive a valid handle or NULL. @var{ctx} is context object to associate MAC
object with. @var{ctx} maybe set to NULL.
For a list of supported algorithms, see @xref{Available MAC algorithms}.
The flags allowed for @var{mode} are:
@c begin table of MAC flags
@table @code
@item GCRY_MAC_FLAG_SECURE
Allocate all buffers and the resulting MAC in "secure memory". Use this if the
MAC data is highly confidential.
@end table
@c begin table of MAC flags
@end deftypefun
@c end function gcry_mac_open
In order to use a handle for performing MAC algorithm operations, a
`key' has to be set first:
@deftypefun gcry_error_t gcry_mac_setkey (gcry_mac_hd_t @var{h}, const void *@var{key}, size_t @var{keylen})
Set the MAC key to the value of @var{key} of length @var{keylen} bytes. With
HMAC algorithms, there is no restriction on the length of the key. With CMAC
algorithms, the length of the key is restricted to those supported by the
underlying block cipher.
@end deftypefun
GMAC algorithms and Poly1305-with-cipher algorithms need initialization vector to be set,
which can be performed with function:
@deftypefun gcry_error_t gcry_mac_setiv (gcry_mac_hd_t @var{h}, const void *@var{iv}, size_t @var{ivlen})
Set the IV to the value of @var{iv} of length @var{ivlen} bytes.
@end deftypefun
After you are done with the MAC calculation, you should release the resources
by using:
@deftypefun void gcry_mac_close (gcry_mac_hd_t @var{h})
Release all resources of MAC context @var{h}. @var{h} should not be
used after a call to this function. A @code{NULL} passed as @var{h} is
ignored. The function also clears all sensitive information associated
with this handle.
@end deftypefun
Often you have to do several MAC operations using the same algorithm.
To avoid the overhead of creating and releasing context, a reset function
is provided:
@deftypefun gcry_error_t gcry_mac_reset (gcry_mac_hd_t @var{h})
Reset the current context to its initial state. This is effectively identical
to a close followed by an open and setting same key.
Note that gcry_mac_reset is implemented as a macro.
@end deftypefun
Now that we have prepared everything to calculate MAC, it is time to
see how it is actually done.
@deftypefun gcry_error_t gcry_mac_write (gcry_mac_hd_t @var{h}, const void *@var{buffer}, size_t @var{length})
Pass @var{length} bytes of the data in @var{buffer} to the MAC object
with handle @var{h} to update the MAC values. If this function is
used after the context has been finalized, it will keep on pushing the
data through the algorithm specific transform function and thereby
change the context; however the results are not meaningful and this
feature is only available to mitigate timing attacks.
@end deftypefun
The way to read out the calculated MAC is by using the function:
@deftypefun gcry_error_t gcry_mac_read (gcry_mac_hd_t @var{h}, void *@var{buffer}, size_t *@var{length})
@code{gcry_mac_read} returns the MAC after finalizing the calculation.
Function copies the resulting MAC value to @var{buffer} of the length
@var{length}. If @var{length} is larger than length of resulting MAC value,
then length of MAC is returned through @var{length}.
@end deftypefun
To compare existing MAC value with recalculated MAC, one is to use the function:
@deftypefun gcry_error_t gcry_mac_verify (gcry_mac_hd_t @var{h}, void *@var{buffer}, size_t @var{length})
@code{gcry_mac_verify} finalizes MAC calculation and compares result with
@var{length} bytes of data in @var{buffer}. Error code @code{GPG_ERR_CHECKSUM}
is returned if the MAC value in the buffer @var{buffer} does not match
the MAC calculated in object @var{h}.
@end deftypefun
In some situations it might be hard to remember the algorithm used for
the MAC calculation. The following function might be used to get that
information:
@deftypefun {int} gcry_mac_get_algo (gcry_mac_hd_t @var{h})
Retrieve the algorithm used with the handle @var{h}.
@end deftypefun
@c ***********************************
@c ***** MAC info functions **********
@c ***********************************
MAC algorithms are identified by internal algorithm numbers (see
@code{gcry_mac_open} for a list). However, in most applications they are
used by names, so two functions are available to map between string
representations and MAC algorithm identifiers.
@deftypefun {const char *} gcry_mac_algo_name (int @var{algo})
Map the MAC algorithm id @var{algo} to a string representation of the
algorithm name. For unknown algorithms this function returns the
string @code{"?"}. This function should not be used to test for the
availability of an algorithm.
@end deftypefun
@deftypefun int gcry_mac_map_name (const char *@var{name})
Map the algorithm with @var{name} to a MAC algorithm identifier.
Returns 0 if the algorithm name is not known. This function should not
be used to test for the availability of an algorithm.
@end deftypefun
To test whether an algorithm is actually available for use, the
following macro should be used:
@deftypefun gcry_error_t gcry_mac_test_algo (int @var{algo})
The macro returns 0 if the MAC algorithm @var{algo} is available for use.
@end deftypefun
If the length of a message digest is not known, it can be retrieved
using the following function:
@deftypefun {unsigned int} gcry_mac_get_algo_maclen (int @var{algo})
Retrieve the length in bytes of the MAC yielded by algorithm @var{algo}.
This is often used prior to @code{gcry_mac_read} to allocate sufficient memory
for the MAC value. On error @code{0} is returned.
@end deftypefun
@deftypefun {unsigned int} gcry_mac_get_algo_keylen (@var{algo})
This function returns length of the key for MAC algorithm @var{algo}. If
the algorithm supports multiple key lengths, the default supported key
length is returned. On error @code{0} is returned. The key length is
returned as number of octets.
@end deftypefun
@c *******************************************************
@c ******************* KDF *****************************
@c *******************************************************
@node Key Derivation
@chapter Key Derivation
@acronym{Libgcypt} provides a general purpose function to derive keys
from strings.
@deftypefun gpg_error_t gcry_kdf_derive ( @
@w{const void *@var{passphrase}}, @w{size_t @var{passphraselen}}, @
@w{int @var{algo}}, @w{int @var{subalgo}}, @
@w{const void *@var{salt}}, @w{size_t @var{saltlen}}, @
@w{unsigned long @var{iterations}}, @
@w{size_t @var{keysize}}, @w{void *@var{keybuffer}} )
Derive a key from a passphrase. @var{keysize} gives the requested
size of the keys in octets. @var{keybuffer} is a caller provided
buffer filled on success with the derived key. The input passphrase
is taken from @var{passphrase} which is an arbitrary memory buffer of
@var{passphraselen} octets. @var{algo} specifies the KDF algorithm to
use; see below. @var{subalgo} specifies an algorithm used internally
by the KDF algorithms; this is usually a hash algorithm but certain
KDF algorithms may use it differently. @var{salt} is a salt of length
@var{saltlen} octets, as needed by most KDF algorithms.
@var{iterations} is a positive integer parameter to most KDFs.
@noindent
On success 0 is returned; on failure an error code.
@noindent
Currently supported KDFs (parameter @var{algo}):
@table @code
@item GCRY_KDF_SIMPLE_S2K
The OpenPGP simple S2K algorithm (cf. RFC4880). Its use is strongly
deprecated. @var{salt} and @var{iterations} are not needed and may be
passed as @code{NULL}/@code{0}.
@item GCRY_KDF_SALTED_S2K
The OpenPGP salted S2K algorithm (cf. RFC4880). Usually not used.
@var{iterations} is not needed and may be passed as @code{0}. @var{saltlen}
must be given as 8.
@item GCRY_KDF_ITERSALTED_S2K
The OpenPGP iterated+salted S2K algorithm (cf. RFC4880). This is the
default for most OpenPGP applications. @var{saltlen} must be given as
8. Note that OpenPGP defines a special encoding of the
@var{iterations}; however this function takes the plain decoded
iteration count.
@item GCRY_KDF_PBKDF2
The PKCS#5 Passphrase Based Key Derivation Function number 2.
@item GCRY_KDF_SCRYPT
The SCRYPT Key Derivation Function. The subalgorithm is used to specify
the CPU/memory cost parameter N, and the number of iterations
is used for the parallelization parameter p. The block size is fixed
at 8 in the current implementation.
@end table
@end deftypefun
@c **********************************************************
@c ******************* Random *****************************
@c **********************************************************
@node Random Numbers
@chapter Random Numbers
@menu
* Quality of random numbers:: Libgcrypt uses different quality levels.
* Retrieving random numbers:: How to retrieve random numbers.
@end menu
@node Quality of random numbers
@section Quality of random numbers
@acronym{Libgcypt} offers random numbers of different quality levels:
@deftp {Data type} gcry_random_level_t
The constants for the random quality levels are of this enum type.
@end deftp
@table @code
@item GCRY_WEAK_RANDOM
For all functions, except for @code{gcry_mpi_randomize}, this level maps
to GCRY_STRONG_RANDOM. If you do not want this, consider using
@code{gcry_create_nonce}.
@item GCRY_STRONG_RANDOM
Use this level for session keys and similar purposes.
@item GCRY_VERY_STRONG_RANDOM
Use this level for long term key material.
@end table
@node Retrieving random numbers
@section Retrieving random numbers
@deftypefun void gcry_randomize (unsigned char *@var{buffer}, size_t @var{length}, enum gcry_random_level @var{level})
Fill @var{buffer} with @var{length} random bytes using a random quality
as defined by @var{level}.
@end deftypefun
@deftypefun {void *} gcry_random_bytes (size_t @var{nbytes}, enum gcry_random_level @var{level})
Convenience function to allocate a memory block consisting of
@var{nbytes} fresh random bytes using a random quality as defined by
@var{level}.
@end deftypefun
@deftypefun {void *} gcry_random_bytes_secure (size_t @var{nbytes}, enum gcry_random_level @var{level})
Convenience function to allocate a memory block consisting of
@var{nbytes} fresh random bytes using a random quality as defined by
@var{level}. This function differs from @code{gcry_random_bytes} in
that the returned buffer is allocated in a ``secure'' area of the
memory.
@end deftypefun
@deftypefun void gcry_create_nonce (unsigned char *@var{buffer}, size_t @var{length})
Fill @var{buffer} with @var{length} unpredictable bytes. This is
commonly called a nonce and may also be used for initialization
vectors and padding. This is an extra function nearly independent of
the other random function for 3 reasons: It better protects the
regular random generator's internal state, provides better performance
and does not drain the precious entropy pool.
@end deftypefun
@c **********************************************************
@c ******************* S-Expressions ***********************
@c **********************************************************
@node S-expressions
@chapter S-expressions
S-expressions are used by the public key functions to pass complex data
structures around. These LISP like objects are used by some
cryptographic protocols (cf. RFC-2692) and Libgcrypt provides functions
to parse and construct them. For detailed information, see
@cite{Ron Rivest, code and description of S-expressions,
@uref{http://theory.lcs.mit.edu/~rivest/sexp.html}}.
@menu
* Data types for S-expressions:: Data types related with S-expressions.
* Working with S-expressions:: How to work with S-expressions.
@end menu
@node Data types for S-expressions
@section Data types for S-expressions
@deftp {Data type} gcry_sexp_t
The @code{gcry_sexp_t} type describes an object with the Libgcrypt internal
representation of an S-expression.
@end deftp
@node Working with S-expressions
@section Working with S-expressions
@noindent
There are several functions to create an Libgcrypt S-expression object
from its external representation or from a string template. There is
also a function to convert the internal representation back into one of
the external formats:
@deftypefun gcry_error_t gcry_sexp_new (@w{gcry_sexp_t *@var{r_sexp}}, @w{const void *@var{buffer}}, @w{size_t @var{length}}, @w{int @var{autodetect}})
This is the generic function to create an new S-expression object from
its external representation in @var{buffer} of @var{length} bytes. On
success the result is stored at the address given by @var{r_sexp}.
With @var{autodetect} set to 0, the data in @var{buffer} is expected to
be in canonized format, with @var{autodetect} set to 1 the parses any of
the defined external formats. If @var{buffer} does not hold a valid
S-expression an error code is returned and @var{r_sexp} set to
@code{NULL}.
Note that the caller is responsible for releasing the newly allocated
S-expression using @code{gcry_sexp_release}.
@end deftypefun
@deftypefun gcry_error_t gcry_sexp_create (@w{gcry_sexp_t *@var{r_sexp}}, @w{void *@var{buffer}}, @w{size_t @var{length}}, @w{int @var{autodetect}}, @w{void (*@var{freefnc})(void*)})
This function is identical to @code{gcry_sexp_new} but has an extra
argument @var{freefnc}, which, when not set to @code{NULL}, is expected
to be a function to release the @var{buffer}; most likely the standard
@code{free} function is used for this argument. This has the effect of
transferring the ownership of @var{buffer} to the created object in
@var{r_sexp}. The advantage of using this function is that Libgcrypt
might decide to directly use the provided buffer and thus avoid extra
copying.
@end deftypefun
@deftypefun gcry_error_t gcry_sexp_sscan (@w{gcry_sexp_t *@var{r_sexp}}, @w{size_t *@var{erroff}}, @w{const char *@var{buffer}}, @w{size_t @var{length}})
This is another variant of the above functions. It behaves nearly
identical but provides an @var{erroff} argument which will receive the
offset into the buffer where the parsing stopped on error.
@end deftypefun
@deftypefun gcry_error_t gcry_sexp_build (@w{gcry_sexp_t *@var{r_sexp}}, @w{size_t *@var{erroff}}, @w{const char *@var{format}, ...})
This function creates an internal S-expression from the string template
@var{format} and stores it at the address of @var{r_sexp}. If there is a
parsing error, the function returns an appropriate error code and stores
the offset into @var{format} where the parsing stopped in @var{erroff}.
The function supports a couple of printf-like formatting characters and
expects arguments for some of these escape sequences right after
@var{format}. The following format characters are defined:
@table @samp
@item %m
The next argument is expected to be of type @code{gcry_mpi_t} and a copy of
its value is inserted into the resulting S-expression. The MPI is
stored as a signed integer.
@item %M
The next argument is expected to be of type @code{gcry_mpi_t} and a copy of
its value is inserted into the resulting S-expression. The MPI is
stored as an unsigned integer.
@item %s
The next argument is expected to be of type @code{char *} and that
string is inserted into the resulting S-expression.
@item %d
The next argument is expected to be of type @code{int} and its value is
inserted into the resulting S-expression.
@item %u
The next argument is expected to be of type @code{unsigned int} and
its value is inserted into the resulting S-expression.
@item %b
The next argument is expected to be of type @code{int} directly
followed by an argument of type @code{char *}. This represents a
buffer of given length to be inserted into the resulting S-expression.
@item %S
The next argument is expected to be of type @code{gcry_sexp_t} and a
copy of that S-expression is embedded in the resulting S-expression.
The argument needs to be a regular S-expression, starting with a
parenthesis.
@end table
@noindent
No other format characters are defined and would return an error. Note
that the format character @samp{%%} does not exists, because a percent
sign is not a valid character in an S-expression.
@end deftypefun
@deftypefun void gcry_sexp_release (@w{gcry_sexp_t @var{sexp}})
Release the S-expression object @var{sexp}. If the S-expression is
stored in secure memory it explicitly zeroises that memory; note that
this is done in addition to the zeroisation always done when freeing
secure memory.
@end deftypefun
@noindent
The next 2 functions are used to convert the internal representation
back into a regular external S-expression format and to show the
structure for debugging.
@deftypefun size_t gcry_sexp_sprint (@w{gcry_sexp_t @var{sexp}}, @w{int @var{mode}}, @w{char *@var{buffer}}, @w{size_t @var{maxlength}})
Copies the S-expression object @var{sexp} into @var{buffer} using the
format specified in @var{mode}. @var{maxlength} must be set to the
allocated length of @var{buffer}. The function returns the actual
length of valid bytes put into @var{buffer} or 0 if the provided buffer
is too short. Passing @code{NULL} for @var{buffer} returns the required
length for @var{buffer}. For convenience reasons an extra byte with
value 0 is appended to the buffer.
@noindent
The following formats are supported:
@table @code
@item GCRYSEXP_FMT_DEFAULT
Returns a convenient external S-expression representation.
@item GCRYSEXP_FMT_CANON
Return the S-expression in canonical format.
@item GCRYSEXP_FMT_BASE64
Not currently supported.
@item GCRYSEXP_FMT_ADVANCED
Returns the S-expression in advanced format.
@end table
@end deftypefun
@deftypefun void gcry_sexp_dump (@w{gcry_sexp_t @var{sexp}})
Dumps @var{sexp} in a format suitable for debugging to Libgcrypt's
logging stream.
@end deftypefun
@noindent
Often canonical encoding is used in the external representation. The
following function can be used to check for valid encoding and to learn
the length of the S-expression.
@deftypefun size_t gcry_sexp_canon_len (@w{const unsigned char *@var{buffer}}, @w{size_t @var{length}}, @w{size_t *@var{erroff}}, @w{int *@var{errcode}})
Scan the canonical encoded @var{buffer} with implicit length values and
return the actual length this S-expression uses. For a valid S-expression
it should never return 0. If @var{length} is not 0, the maximum
length to scan is given; this can be used for syntax checks of
data passed from outside. @var{errcode} and @var{erroff} may both be
passed as @code{NULL}.
@end deftypefun
@noindent
There are functions to parse S-expressions and retrieve elements:
@deftypefun gcry_sexp_t gcry_sexp_find_token (@w{const gcry_sexp_t @var{list}}, @w{const char *@var{token}}, @w{size_t @var{toklen}})
Scan the S-expression for a sublist with a type (the car of the list)
matching the string @var{token}. If @var{toklen} is not 0, the token is
assumed to be raw memory of this length. The function returns a newly
allocated S-expression consisting of the found sublist or @code{NULL}
when not found.
@end deftypefun
@deftypefun int gcry_sexp_length (@w{const gcry_sexp_t @var{list}})
Return the length of the @var{list}. For a valid S-expression this
should be at least 1.
@end deftypefun
@deftypefun gcry_sexp_t gcry_sexp_nth (@w{const gcry_sexp_t @var{list}}, @w{int @var{number}})
Create and return a new S-expression from the element with index @var{number} in
@var{list}. Note that the first element has the index 0. If there is
no such element, @code{NULL} is returned.
@end deftypefun
@deftypefun gcry_sexp_t gcry_sexp_car (@w{const gcry_sexp_t @var{list}})
Create and return a new S-expression from the first element in
@var{list}; this is called the "type" and should always exist per
S-expression specification and in general be a string. @code{NULL} is
returned in case of a problem.
@end deftypefun
@deftypefun gcry_sexp_t gcry_sexp_cdr (@w{const gcry_sexp_t @var{list}})
Create and return a new list form all elements except for the first one.
Note that this function may return an invalid S-expression because it
is not guaranteed, that the type exists and is a string. However, for
parsing a complex S-expression it might be useful for intermediate
lists. Returns @code{NULL} on error.
@end deftypefun
@deftypefun {const char *} gcry_sexp_nth_data (@w{const gcry_sexp_t @var{list}}, @w{int @var{number}}, @w{size_t *@var{datalen}})
This function is used to get data from a @var{list}. A pointer to the
actual data with index @var{number} is returned and the length of this
data will be stored to @var{datalen}. If there is no data at the given
index or the index represents another list, @code{NULL} is returned.
@strong{Caution:} The returned pointer is valid as long as @var{list} is
not modified or released.
@noindent
Here is an example on how to extract and print the surname (Meier) from
the S-expression @samp{(Name Otto Meier (address Burgplatz 3))}:
@example
size_t len;
const char *name;
name = gcry_sexp_nth_data (list, 2, &len);
printf ("my name is %.*s\n", (int)len, name);
@end example
@end deftypefun
@deftypefun {void *} gcry_sexp_nth_buffer (@w{const gcry_sexp_t @var{list}}, @w{int @var{number}}, @w{size_t *@var{rlength}})
This function is used to get data from a @var{list}. A malloced
buffer with the actual data at list index @var{number} is returned and
the length of this buffer will be stored to @var{rlength}. If there
is no data at the given index or the index represents another list,
@code{NULL} is returned. The caller must release the result using
@code{gcry_free}.
@noindent
Here is an example on how to extract and print the CRC value from the
S-expression @samp{(hash crc32 #23ed00d7)}:
@example
size_t len;
char *value;
value = gcry_sexp_nth_buffer (list, 2, &len);
if (value)
fwrite (value, len, 1, stdout);
gcry_free (value);
@end example
@end deftypefun
@deftypefun {char *} gcry_sexp_nth_string (@w{gcry_sexp_t @var{list}}, @w{int @var{number}})
This function is used to get and convert data from a @var{list}. The
data is assumed to be a Nul terminated string. The caller must
release this returned value using @code{gcry_free}. If there is
no data at the given index, the index represents a list or the value
can't be converted to a string, @code{NULL} is returned.
@end deftypefun
@deftypefun gcry_mpi_t gcry_sexp_nth_mpi (@w{gcry_sexp_t @var{list}}, @w{int @var{number}}, @w{int @var{mpifmt}})
This function is used to get and convert data from a @var{list}. This
data is assumed to be an MPI stored in the format described by
@var{mpifmt} and returned as a standard Libgcrypt MPI. The caller must
release this returned value using @code{gcry_mpi_release}. If there is
no data at the given index, the index represents a list or the value
can't be converted to an MPI, @code{NULL} is returned. If you use
this function to parse results of a public key function, you most
likely want to use @code{GCRYMPI_FMT_USG}.
@end deftypefun
@deftypefun gpg_error_t gcry_sexp_extract_param ( @
@w{gcry_sexp_t @var{sexp}}, @
@w{const char *@var{path}}, @
@w{const char *@var{list}}, ...)
Extract parameters from an S-expression using a list of parameter
names. The names of these parameters are specified in LIST. White
space between the parameter names are ignored. Some special characters
may be given to control the conversion:
@table @samp
@item +
Switch to unsigned integer format (GCRYMPI_FMT_USG). This is the
default mode.
@item -
Switch to standard signed format (GCRYMPI_FMT_STD).
@item /
Switch to opaque MPI format. The resulting MPIs may not be used for
computations; see @code{gcry_mpi_get_opaque} for details.
@item &
Switch to buffer descriptor mode. See below for details.
@item ?
If immediately following a parameter letter (no white space allowed),
that parameter is considered optional.
@end table
In general parameter names are single letters. To use a string for a
parameter name, enclose the name in single quotes.
Unless in buffer descriptor mode for each parameter name a pointer to
an @code{gcry_mpi_t} variable is expected that must be set to
@code{NULL} prior to invoking this function, and finally a @code{NULL}
is expected. For example
@example
_gcry_sexp_extract_param (key, NULL, "n/x+e d-'foo'",
&mpi_n, &mpi_x, &mpi_e, &mpi_foo, NULL)
@end example
stores the parameter 'n' from @var{key} as an unsigned MPI into
@var{mpi_n}, the parameter 'x' as an opaque MPI into @var{mpi_x}, the
parameter 'e' again as an unsigned MPI into @var{mpi_e}, and the
parameter 'foo' as a signed MPI.
@var{path} is an optional string used to locate a token. The
exclamation mark separated tokens are used via
@code{gcry_sexp_find_token} to find a start point inside the
S-expression.
In buffer descriptor mode a pointer to a @code{gcry_buffer_t}
descriptor is expected instead of a pointer to an MPI. The caller may
use two different operation modes here: If the @var{data} field of the
provided descriptor is @code{NULL}, the function allocates a new
buffer and stores it at @var{data}; the other fields are set
accordingly with @var{off} set to 0. If @var{data} is not
@code{NULL}, the function assumes that the @var{data}, @var{size}, and
@var{off} fields specify a buffer where to but the value of the
respective parameter; on return the @var{len} field receives the
number of bytes copied to that buffer; in case the buffer is too
small, the function immediately returns with an error code (and
@var{len} is set to 0).
The function returns 0 on success. On error an error code is
returned, all passed MPIs that might have been allocated up to this
point are deallocated and set to @code{NULL}, and all passed buffers
are either truncated if the caller supplied the buffer, or deallocated
if the function allocated the buffer.
@end deftypefun
@c **********************************************************
@c ******************* MPIs ******** ***********************
@c **********************************************************
@node MPI library
@chapter MPI library
@menu
* Data types:: MPI related data types.
* Basic functions:: First steps with MPI numbers.
* MPI formats:: External representation of MPIs.
* Calculations:: Performing MPI calculations.
* Comparisons:: How to compare MPI values.
* Bit manipulations:: How to access single bits of MPI values.
* EC functions:: Elliptic curve related functions.
* Miscellaneous:: Miscellaneous MPI functions.
@end menu
Public key cryptography is based on mathematics with large numbers. To
implement the public key functions, a library for handling these large
numbers is required. Because of the general usefulness of such a
library, its interface is exposed by Libgcrypt.
In the context of Libgcrypt and in most other applications, these large
numbers are called MPIs (multi-precision-integers).
@node Data types
@section Data types
@deftp {Data type} {gcry_mpi_t}
This type represents an object to hold an MPI.
@end deftp
@deftp {Data type} {gcry_mpi_point_t}
This type represents an object to hold a point for elliptic curve math.
@end deftp
@node Basic functions
@section Basic functions
@noindent
To work with MPIs, storage must be allocated and released for the
numbers. This can be done with one of these functions:
@deftypefun gcry_mpi_t gcry_mpi_new (@w{unsigned int @var{nbits}})
Allocate a new MPI object, initialize it to 0 and initially allocate
enough memory for a number of at least @var{nbits}. This pre-allocation is
only a small performance issue and not actually necessary because
Libgcrypt automatically re-allocates the required memory.
@end deftypefun
@deftypefun gcry_mpi_t gcry_mpi_snew (@w{unsigned int @var{nbits}})
This is identical to @code{gcry_mpi_new} but allocates the MPI in the so
called "secure memory" which in turn will take care that all derived
values will also be stored in this "secure memory". Use this for highly
confidential data like private key parameters.
@end deftypefun
@deftypefun gcry_mpi_t gcry_mpi_copy (@w{const gcry_mpi_t @var{a}})
Create a new MPI as the exact copy of @var{a} but with the constant
and immutable flags cleared.
@end deftypefun
@deftypefun void gcry_mpi_release (@w{gcry_mpi_t @var{a}})
Release the MPI @var{a} and free all associated resources. Passing
@code{NULL} is allowed and ignored. When a MPI stored in the "secure
memory" is released, that memory gets wiped out immediately.
@end deftypefun
@noindent
The simplest operations are used to assign a new value to an MPI:
@deftypefun gcry_mpi_t gcry_mpi_set (@w{gcry_mpi_t @var{w}}, @w{const gcry_mpi_t @var{u}})
Assign the value of @var{u} to @var{w} and return @var{w}. If
@code{NULL} is passed for @var{w}, a new MPI is allocated, set to the
value of @var{u} and returned.
@end deftypefun
@deftypefun gcry_mpi_t gcry_mpi_set_ui (@w{gcry_mpi_t @var{w}}, @w{unsigned long @var{u}})
Assign the value of @var{u} to @var{w} and return @var{w}. If
@code{NULL} is passed for @var{w}, a new MPI is allocated, set to the
value of @var{u} and returned. This function takes an @code{unsigned
int} as type for @var{u} and thus it is only possible to set @var{w} to
small values (usually up to the word size of the CPU).
@end deftypefun
@deftypefun gcry_error_t gcry_mpi_get_ui (@w{unsigned int *@var{w}}, @w{gcry_mpi_t @var{u}})
If @var{u} is not negative and small enough to be stored in an
@code{unsigned int} variable, store its value at @var{w}. If the
value does not fit or is negative return GPG_ERR_ERANGE and do not
change the value stored at @var{w}. Note that this function returns
an @code{unsigned int} so that this value can immediately be used with
the bit test functions. This is in contrast to the other "_ui"
functions which allow for values up to an @code{unsigned long}.
@end deftypefun
@deftypefun void gcry_mpi_swap (@w{gcry_mpi_t @var{a}}, @w{gcry_mpi_t @var{b}})
Swap the values of @var{a} and @var{b}.
@end deftypefun
@deftypefun void gcry_mpi_snatch (@w{gcry_mpi_t @var{w}}, @
@w{const gcry_mpi_t @var{u}})
Set @var{u} into @var{w} and release @var{u}. If @var{w} is
@code{NULL} only @var{u} will be released.
@end deftypefun
@deftypefun void gcry_mpi_neg (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}})
Set the sign of @var{w} to the negative of @var{u}.
@end deftypefun
@deftypefun void gcry_mpi_abs (@w{gcry_mpi_t @var{w}})
Clear the sign of @var{w}.
@end deftypefun
@node MPI formats
@section MPI formats
@noindent
The following functions are used to convert between an external
representation of an MPI and the internal one of Libgcrypt.
@deftypefun gcry_error_t gcry_mpi_scan (@w{gcry_mpi_t *@var{r_mpi}}, @w{enum gcry_mpi_format @var{format}}, @w{const unsigned char *@var{buffer}}, @w{size_t @var{buflen}}, @w{size_t *@var{nscanned}})
Convert the external representation of an integer stored in @var{buffer}
with a length of @var{buflen} into a newly created MPI returned which
will be stored at the address of @var{r_mpi}. For certain formats the
length argument is not required and should be passed as @code{0}. A
@var{buflen} larger than 16 MiByte will be rejected. After a
successful operation the variable @var{nscanned} receives the number of
bytes actually scanned unless @var{nscanned} was given as
@code{NULL}. @var{format} describes the format of the MPI as stored in
@var{buffer}:
@table @code
@item GCRYMPI_FMT_STD
2-complement stored without a length header. Note that
@code{gcry_mpi_print} stores a @code{0} as a string of zero length.
@item GCRYMPI_FMT_PGP
As used by OpenPGP (only defined as unsigned). This is basically
@code{GCRYMPI_FMT_STD} with a 2 byte big endian length header.
A length header indicating a length of more than 16384 is not allowed.
@item GCRYMPI_FMT_SSH
As used in the Secure Shell protocol. This is @code{GCRYMPI_FMT_STD}
with a 4 byte big endian header.
@item GCRYMPI_FMT_HEX
Stored as a string with each byte of the MPI encoded as 2 hex digits.
Negative numbers are prefix with a minus sign and in addition the
high bit is always zero to make clear that an explicit sign ist used.
When using this format, @var{buflen} must be zero.
@item GCRYMPI_FMT_USG
Simple unsigned integer.
@end table
@noindent
Note that all of the above formats store the integer in big-endian
format (MSB first).
@end deftypefun
@deftypefun gcry_error_t gcry_mpi_print (@w{enum gcry_mpi_format @var{format}}, @w{unsigned char *@var{buffer}}, @w{size_t @var{buflen}}, @w{size_t *@var{nwritten}}, @w{const gcry_mpi_t @var{a}})
Convert the MPI @var{a} into an external representation described by
@var{format} (see above) and store it in the provided @var{buffer}
which has a usable length of at least the @var{buflen} bytes. If
@var{nwritten} is not NULL, it will receive the number of bytes
actually stored in @var{buffer} after a successful operation.
@end deftypefun
@deftypefun gcry_error_t gcry_mpi_aprint (@w{enum gcry_mpi_format @var{format}}, @w{unsigned char **@var{buffer}}, @w{size_t *@var{nbytes}}, @w{const gcry_mpi_t @var{a}})
Convert the MPI @var{a} into an external representation described by
@var{format} (see above) and store it in a newly allocated buffer which
address will be stored in the variable @var{buffer} points to. The
number of bytes stored in this buffer will be stored in the variable
@var{nbytes} points to, unless @var{nbytes} is @code{NULL}.
Even if @var{nbytes} is zero, the function allocates at least one byte
and store a zero there. Thus with formats @code{GCRYMPI_FMT_STD} and
@code{GCRYMPI_FMT_USG} the caller may safely set a returned length of
0 to 1 to represent a zero as a 1 byte string.
@end deftypefun
@deftypefun void gcry_mpi_dump (@w{const gcry_mpi_t @var{a}})
Dump the value of @var{a} in a format suitable for debugging to
Libgcrypt's logging stream. Note that one leading space but no trailing
space or linefeed will be printed. It is okay to pass @code{NULL} for
@var{a}.
@end deftypefun
@node Calculations
@section Calculations
@noindent
Basic arithmetic operations:
@deftypefun void gcry_mpi_add (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}}, @w{gcry_mpi_t @var{v}})
@math{@var{w} = @var{u} + @var{v}}.
@end deftypefun
@deftypefun void gcry_mpi_add_ui (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}}, @w{unsigned long @var{v}})
@math{@var{w} = @var{u} + @var{v}}. Note that @var{v} is an unsigned integer.
@end deftypefun
@deftypefun void gcry_mpi_addm (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}}, @w{gcry_mpi_t @var{v}}, @w{gcry_mpi_t @var{m}})
@math{@var{w} = @var{u} + @var{v} \bmod @var{m}}.
@end deftypefun
@deftypefun void gcry_mpi_sub (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}}, @w{gcry_mpi_t @var{v}})
@math{@var{w} = @var{u} - @var{v}}.
@end deftypefun
@deftypefun void gcry_mpi_sub_ui (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}}, @w{unsigned long @var{v}})
@math{@var{w} = @var{u} - @var{v}}. @var{v} is an unsigned integer.
@end deftypefun
@deftypefun void gcry_mpi_subm (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}}, @w{gcry_mpi_t @var{v}}, @w{gcry_mpi_t @var{m}})
@math{@var{w} = @var{u} - @var{v} \bmod @var{m}}.
@end deftypefun
@deftypefun void gcry_mpi_mul (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}}, @w{gcry_mpi_t @var{v}})
@math{@var{w} = @var{u} * @var{v}}.
@end deftypefun
@deftypefun void gcry_mpi_mul_ui (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}}, @w{unsigned long @var{v}})
@math{@var{w} = @var{u} * @var{v}}. @var{v} is an unsigned integer.
@end deftypefun
@deftypefun void gcry_mpi_mulm (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}}, @w{gcry_mpi_t @var{v}}, @w{gcry_mpi_t @var{m}})
@math{@var{w} = @var{u} * @var{v} \bmod @var{m}}.
@end deftypefun
@deftypefun void gcry_mpi_mul_2exp (@w{gcry_mpi_t @var{w}}, @w{gcry_mpi_t @var{u}}, @w{unsigned long @var{e}})
@c FIXME: I am in need for a real TeX{info} guru:
@c I don't know why TeX can grok @var{e} here.
@math{@var{w} = @var{u} * 2^e}.
@end deftypefun
@deftypefun void gcry_mpi_div (@w{gcry_mpi_t @var{q}}, @w{gcry_mpi_t @var{r}}, @w{gcry_mpi_t @var{dividend}}, @w{gcry_mpi_t @var{divisor}}, @w{int @var{round}})
@math{@var{q} = @var{dividend} / @var{divisor}}, @math{@var{r} =
@var{dividend} \bmod @var{divisor}}. @var{q} and @var{r} may be passed
as @code{NULL}. @var{round} is either negative for floored division
(rounds towards the next lower integer) or zero for truncated division
(rounds towards zero).
@end deftypefun
@deftypefun void gcry_mpi_mod (@w{gcry_mpi_t @var{r}}, @w{gcry_mpi_t @var{dividend}}, @w{gcry_mpi_t @var{divisor}})
@math{@var{r} = @var{dividend} \bmod @var{divisor}}.
@end deftypefun
@deftypefun void gcry_mpi_powm (@w{gcry_mpi_t @var{w}}, @w{const gcry_mpi_t @var{b}}, @w{const gcry_mpi_t @var{e}}, @w{const gcry_mpi_t @var{m}})
@c I don't know why TeX can grok @var{e} here.
@math{@var{w} = @var{b}^e \bmod @var{m}}.
@end deftypefun
@deftypefun int gcry_mpi_gcd (@w{gcry_mpi_t @var{g}}, @w{gcry_mpi_t @var{a}}, @w{gcry_mpi_t @var{b}})
Set @var{g} to the greatest common divisor of @var{a} and @var{b}.
Return true if the @var{g} is 1.
@end deftypefun
@deftypefun int gcry_mpi_invm (@w{gcry_mpi_t @var{x}}, @w{gcry_mpi_t @var{a}}, @w{gcry_mpi_t @var{m}})
Set @var{x} to the multiplicative inverse of @math{@var{a} \bmod @var{m}}.
Return true if the inverse exists.
@end deftypefun
@node Comparisons
@section Comparisons
@noindent
The next 2 functions are used to compare MPIs:
@deftypefun int gcry_mpi_cmp (@w{const gcry_mpi_t @var{u}}, @w{const gcry_mpi_t @var{v}})
Compare the multi-precision-integers number @var{u} and @var{v}
returning 0 for equality, a positive value for @var{u} > @var{v} and a
negative for @var{u} < @var{v}. If both numbers are opaque values
(cf, gcry_mpi_set_opaque) the comparison is done by checking the bit
sizes using memcmp. If only one number is an opaque value, the opaque
value is less than the other number.
@end deftypefun
@deftypefun int gcry_mpi_cmp_ui (@w{const gcry_mpi_t @var{u}}, @w{unsigned long @var{v}})
Compare the multi-precision-integers number @var{u} with the unsigned
integer @var{v} returning 0 for equality, a positive value for @var{u} >
@var{v} and a negative for @var{u} < @var{v}.
@end deftypefun
@deftypefun int gcry_mpi_is_neg (@w{const gcry_mpi_t @var{a}})
Return 1 if @var{a} is less than zero; return 0 if zero or positive.
@end deftypefun
@node Bit manipulations
@section Bit manipulations
@noindent
There are a couple of functions to get information on arbitrary bits
in an MPI and to set or clear them:
@deftypefun {unsigned int} gcry_mpi_get_nbits (@w{gcry_mpi_t @var{a}})
Return the number of bits required to represent @var{a}.
@end deftypefun
@deftypefun int gcry_mpi_test_bit (@w{gcry_mpi_t @var{a}}, @w{unsigned int @var{n}})
Return true if bit number @var{n} (counting from 0) is set in @var{a}.
@end deftypefun
@deftypefun void gcry_mpi_set_bit (@w{gcry_mpi_t @var{a}}, @w{unsigned int @var{n}})
Set bit number @var{n} in @var{a}.
@end deftypefun
@deftypefun void gcry_mpi_clear_bit (@w{gcry_mpi_t @var{a}}, @w{unsigned int @var{n}})
Clear bit number @var{n} in @var{a}.
@end deftypefun
@deftypefun void gcry_mpi_set_highbit (@w{gcry_mpi_t @var{a}}, @w{unsigned int @var{n}})
Set bit number @var{n} in @var{a} and clear all bits greater than @var{n}.
@end deftypefun
@deftypefun void gcry_mpi_clear_highbit (@w{gcry_mpi_t @var{a}}, @w{unsigned int @var{n}})
Clear bit number @var{n} in @var{a} and all bits greater than @var{n}.
@end deftypefun
@deftypefun void gcry_mpi_rshift (@w{gcry_mpi_t @var{x}}, @w{gcry_mpi_t @var{a}}, @w{unsigned int @var{n}})
Shift the value of @var{a} by @var{n} bits to the right and store the
result in @var{x}.
@end deftypefun
@deftypefun void gcry_mpi_lshift (@w{gcry_mpi_t @var{x}}, @w{gcry_mpi_t @var{a}}, @w{unsigned int @var{n}})
Shift the value of @var{a} by @var{n} bits to the left and store the
result in @var{x}.
@end deftypefun
@node EC functions
@section EC functions
@noindent
Libgcrypt provides an API to access low level functions used by its
elliptic curve implementation. These functions allow to implement
elliptic curve methods for which no explicit support is available.
@deftypefun gcry_mpi_point_t gcry_mpi_point_new (@w{unsigned int @var{nbits}})
Allocate a new point object, initialize it to 0, and allocate enough
memory for a points of at least @var{nbits}. This pre-allocation
yields only a small performance win and is not really necessary
because Libgcrypt automatically re-allocates the required memory.
Using 0 for @var{nbits} is usually the right thing to do.
@end deftypefun
@deftypefun void gcry_mpi_point_release (@w{gcry_mpi_point_t @var{point}})
Release @var{point} and free all associated resources. Passing
@code{NULL} is allowed and ignored.
@end deftypefun
@deftypefun gcry_mpi_point_t gcry_mpi_point_copy (@w{gcry_mpi_point_t @var{point}})
Allocate and return a new point object and initialize it with
@var{point}. If @var{point} is NULL the function is identical to
@code{gcry_mpi_point_new(0)}.
@end deftypefun
@deftypefun void gcry_mpi_point_get (@w{gcry_mpi_t @var{x}}, @
@w{gcry_mpi_t @var{y}}, @w{gcry_mpi_t @var{z}}, @
@w{gcry_mpi_point_t @var{point}})
Store the projective coordinates from @var{point} into the MPIs
@var{x}, @var{y}, and @var{z}. If a coordinate is not required,
@code{NULL} may be used for @var{x}, @var{y}, or @var{z}.
@end deftypefun
@deftypefun void gcry_mpi_point_snatch_get (@w{gcry_mpi_t @var{x}}, @
@w{gcry_mpi_t @var{y}}, @w{gcry_mpi_t @var{z}}, @
@w{gcry_mpi_point_t @var{point}})
Store the projective coordinates from @var{point} into the MPIs
@var{x}, @var{y}, and @var{z}. If a coordinate is not required,
@code{NULL} may be used for @var{x}, @var{y}, or @var{z}. The object
@var{point} is then released. Using this function instead of
@code{gcry_mpi_point_get} and @code{gcry_mpi_point_release} has the
advantage of avoiding some extra memory allocations and copies.
@end deftypefun
@deftypefun gcry_mpi_point_t gcry_mpi_point_set ( @
@w{gcry_mpi_point_t @var{point}}, @
@w{gcry_mpi_t @var{x}}, @w{gcry_mpi_t @var{y}}, @w{gcry_mpi_t @var{z}})
Store the projective coordinates from @var{x}, @var{y}, and @var{z}
into @var{point}. If a coordinate is given as @code{NULL}, the value
0 is used. If @code{NULL} is used for @var{point} a new point object
is allocated and returned. Returns @var{point} or the newly allocated
point object.
@end deftypefun
@deftypefun gcry_mpi_point_t gcry_mpi_point_snatch_set ( @
@w{gcry_mpi_point_t @var{point}}, @
@w{gcry_mpi_t @var{x}}, @w{gcry_mpi_t @var{y}}, @w{gcry_mpi_t @var{z}})
Store the projective coordinates from @var{x}, @var{y}, and @var{z}
into @var{point}. If a coordinate is given as @code{NULL}, the value
0 is used. If @code{NULL} is used for @var{point} a new point object
is allocated and returned. The MPIs @var{x}, @var{y}, and @var{z} are
released. Using this function instead of @code{gcry_mpi_point_set}
and 3 calls to @code{gcry_mpi_release} has the advantage of avoiding
some extra memory allocations and copies. Returns @var{point} or the
newly allocated point object.
@end deftypefun
@anchor{gcry_mpi_ec_new}
@deftypefun gpg_error_t gcry_mpi_ec_new (@w{gcry_ctx_t *@var{r_ctx}}, @
@w{gcry_sexp_t @var{keyparam}}, @w{const char *@var{curvename}})
Allocate a new context for elliptic curve operations. If
@var{keyparam} is given it specifies the parameters of the curve
(@pxref{ecc_keyparam}). If @var{curvename} is given in addition to
@var{keyparam} and the key parameters do not include a named curve
reference, the string @var{curvename} is used to fill in missing
parameters. If only @var{curvename} is given, the context is
initialized for this named curve.
If a parameter specifying a point (e.g. @code{g} or @code{q}) is not
found, the parser looks for a non-encoded point by appending
@code{.x}, @code{.y}, and @code{.z} to the parameter name and looking
them all up to create a point. A parameter with the suffix @code{.z}
is optional and defaults to 1.
On success the function returns 0 and stores the new context object at
@var{r_ctx}; this object eventually needs to be released
(@pxref{gcry_ctx_release}). On error the function stores @code{NULL} at
@var{r_ctx} and returns an error code.
@end deftypefun
@deftypefun gcry_mpi_t gcry_mpi_ec_get_mpi ( @
@w{const char *@var{name}}, @w{gcry_ctx_t @var{ctx}}, @w{int @var{copy}})
Return the MPI with @var{name} from the context @var{ctx}. If not
found @code{NULL} is returned. If the returned MPI may later be
modified, it is suggested to pass @code{1} to @var{copy}, so that the
function guarantees that a modifiable copy of the MPI is returned. If
@code{0} is used for @var{copy}, this function may return a constant
flagged MPI. In any case @code{gcry_mpi_release} needs to be called
to release the result. For valid names @ref{ecc_keyparam}. If the
public key @code{q} is requested but only the private key @code{d} is
available, @code{q} will be recomputed on the fly. If a point
parameter is requested it is returned as an uncompressed
encoded point unless these special names are used:
@table @var
@item q@@eddsa
Return an EdDSA style compressed point. This is only supported for
Twisted Edwards curves.
@end table
@end deftypefun
@deftypefun gcry_mpi_point_t gcry_mpi_ec_get_point ( @
@w{const char *@var{name}}, @w{gcry_ctx_t @var{ctx}}, @w{int @var{copy}})
Return the point with @var{name} from the context @var{ctx}. If not
found @code{NULL} is returned. If the returned MPI may later be
modified, it is suggested to pass @code{1} to @var{copy}, so that the
function guarantees that a modifiable copy of the MPI is returned. If
@code{0} is used for @var{copy}, this function may return a constant
flagged point. In any case @code{gcry_mpi_point_release} needs to be
called to release the result. If the public key @code{q} is requested
but only the private key @code{d} is available, @code{q} will be
recomputed on the fly.
@end deftypefun
@deftypefun gpg_error_t gcry_mpi_ec_set_mpi ( @
@w{const char *@var{name}}, @w{gcry_mpi_t @var{newvalue}}, @
@w{gcry_ctx_t @var{ctx}})
Store the MPI @var{newvalue} at @var{name} into the context @var{ctx}.
On success @code{0} is returned; on error an error code. Valid names
are the MPI parameters of an elliptic curve (@pxref{ecc_keyparam}).
@end deftypefun
@deftypefun gpg_error_t gcry_mpi_ec_set_point ( @
@w{const char *@var{name}}, @w{gcry_mpi_point_t @var{newvalue}}, @
@w{gcry_ctx_t @var{ctx}})
Store the point @var{newvalue} at @var{name} into the context
@var{ctx}. On success @code{0} is returned; on error an error code.
Valid names are the point parameters of an elliptic curve
(@pxref{ecc_keyparam}).
@end deftypefun
@deftypefun gpg_err_code_t gcry_mpi_ec_decode_point ( @
@w{mpi_point_t @var{result}}, @w{gcry_mpi_t @var{value}}, @
@w{gcry_ctx_t @var{ctx}})
Decode the point given as an MPI in @var{value} and store at
@var{result}. To decide which encoding is used the function takes a
context @var{ctx} which can be created with @code{gcry_mpi_ec_new}.
If @code{NULL} is given for the context the function assumes a 0x04
prefixed uncompressed encoding. On error an error code is returned
and @var{result} might be changed.
@end deftypefun
@deftypefun int gcry_mpi_ec_get_affine ( @
@w{gcry_mpi_t @var{x}}, @w{gcry_mpi_t @var{y}}, @
@w{gcry_mpi_point_t @var{point}}, @w{gcry_ctx_t @var{ctx}})
Compute the affine coordinates from the projective coordinates in
@var{point} and store them into @var{x} and @var{y}. If one
coordinate is not required, @code{NULL} may be passed to @var{x} or
@var{y}. @var{ctx} is the context object which has been created using
@code{gcry_mpi_ec_new}. Returns 0 on success or not 0 if @var{point}
is at infinity.
Note that you can use @code{gcry_mpi_ec_set_point} with the value
@code{GCRYMPI_CONST_ONE} for @var{z} to convert affine coordinates
back into projective coordinates.
@end deftypefun
@deftypefun void gcry_mpi_ec_dup ( @
@w{gcry_mpi_point_t @var{w}}, @w{gcry_mpi_point_t @var{u}}, @
@w{gcry_ctx_t @var{ctx}})
Double the point @var{u} of the elliptic curve described by @var{ctx}
and store the result into @var{w}.
@end deftypefun
@deftypefun void gcry_mpi_ec_add ( @
@w{gcry_mpi_point_t @var{w}}, @w{gcry_mpi_point_t @var{u}}, @
@w{gcry_mpi_point_t @var{v}}, @w{gcry_ctx_t @var{ctx}})
Add the points @var{u} and @var{v} of the elliptic curve described by
@var{ctx} and store the result into @var{w}.
@end deftypefun
@deftypefun void gcry_mpi_ec_sub ( @
@w{gcry_mpi_point_t @var{w}}, @w{gcry_mpi_point_t @var{u}}, @
@w{gcry_mpi_point_t @var{v}}, @w{gcry_ctx_t @var{ctx}})
Subtracts the point @var{v} from the point @var{u} of the elliptic
curve described by @var{ctx} and store the result into @var{w}. Only
Twisted Edwards curves are supported for now.
@end deftypefun
@deftypefun void gcry_mpi_ec_mul ( @
@w{gcry_mpi_point_t @var{w}}, @w{gcry_mpi_t @var{n}}, @
@w{gcry_mpi_point_t @var{u}}, @w{gcry_ctx_t @var{ctx}})
Multiply the point @var{u} of the elliptic curve described by
@var{ctx} by @var{n} and store the result into @var{w}.
@end deftypefun
@deftypefun int gcry_mpi_ec_curve_point ( @
@w{gcry_mpi_point_t @var{point}}, @w{gcry_ctx_t @var{ctx}})
Return true if @var{point} is on the elliptic curve described by
@var{ctx}.
@end deftypefun
@node Miscellaneous
@section Miscellaneous
An MPI data type is allowed to be ``misused'' to store an arbitrary
value. Two functions implement this kludge:
@deftypefun gcry_mpi_t gcry_mpi_set_opaque (@w{gcry_mpi_t @var{a}}, @w{void *@var{p}}, @w{unsigned int @var{nbits}})
Store @var{nbits} of the value @var{p} points to in @var{a} and mark
@var{a} as an opaque value (i.e. an value that can't be used for any
math calculation and is only used to store an arbitrary bit pattern in
@var{a}). Ownership of @var{p} is taken by this function and thus the
user may not use dereference the passed value anymore. It is required
that them memory referenced by @var{p} has been allocated in a way
that @code{gcry_free} is able to release it.
WARNING: Never use an opaque MPI for actual math operations. The only
valid functions are gcry_mpi_get_opaque and gcry_mpi_release. Use
gcry_mpi_scan to convert a string of arbitrary bytes into an MPI.
@end deftypefun
@deftypefun gcry_mpi_t gcry_mpi_set_opaque_copy (@w{gcry_mpi_t @var{a}}, @w{const void *@var{p}}, @w{unsigned int @var{nbits}})
Same as @code{gcry_mpi_set_opaque} but ownership of @var{p} is not
taken instead a copy of @var{p} is used.
@end deftypefun
@deftypefun {void *} gcry_mpi_get_opaque (@w{gcry_mpi_t @var{a}}, @w{unsigned int *@var{nbits}})
Return a pointer to an opaque value stored in @var{a} and return its
size in @var{nbits}. Note that the returned pointer is still owned by
@var{a} and that the function should never be used for an non-opaque
MPI.
@end deftypefun
Each MPI has an associated set of flags for special purposes. The
currently defined flags are:
@table @code
@item GCRYMPI_FLAG_SECURE
Setting this flag converts @var{a} into an MPI stored in "secure
memory". Clearing this flag is not allowed.
@item GCRYMPI_FLAG_OPAQUE
This is an internal flag, indicating the an opaque valuue and not an
integer is stored. This is an read-only flag; it may not be set or
cleared.
@item GCRYMPI_FLAG_IMMUTABLE
If this flag is set, the MPI is marked as immutable. Setting or
changing the value of that MPI is ignored and an error message is
logged. The flag is sometimes useful for debugging.
@item GCRYMPI_FLAG_CONST
If this flag is set, the MPI is marked as a constant and as immutable
Setting or changing the value of that MPI is ignored and an error
message is logged. Such an MPI will never be deallocated and may thus
be used without copying. Note that using gcry_mpi_copy will return a
copy of that constant with this and the immutable flag cleared. A few
commonly used constants are pre-defined and accessible using the
macros @code{GCRYMPI_CONST_ONE}, @code{GCRYMPI_CONST_TWO},
@code{GCRYMPI_CONST_THREE}, @code{GCRYMPI_CONST_FOUR}, and
@code{GCRYMPI_CONST_EIGHT}.
@item GCRYMPI_FLAG_USER1
@itemx GCRYMPI_FLAG_USER2
@itemx GCRYMPI_FLAG_USER3
@itemx GCRYMPI_FLAG_USER4
These flags are reserved for use by the application.
@end table
@deftypefun void gcry_mpi_set_flag (@w{gcry_mpi_t @var{a}}, @
@w{enum gcry_mpi_flag @var{flag}})
Set the @var{flag} for the MPI @var{a}. The only allowed flags are
@code{GCRYMPI_FLAG_SECURE}, @code{GCRYMPI_FLAG_IMMUTABLE}, and
@code{GCRYMPI_FLAG_CONST}.
@end deftypefun
@deftypefun void gcry_mpi_clear_flag (@w{gcry_mpi_t @var{a}}, @
@w{enum gcry_mpi_flag @var{flag}})
Clear @var{flag} for the multi-precision-integers @var{a}. The only
allowed flag is @code{GCRYMPI_FLAG_IMMUTABLE} but only if
@code{GCRYMPI_FLAG_CONST} is not set. If @code{GCRYMPI_FLAG_CONST} is
set, clearing @code{GCRYMPI_FLAG_IMMUTABLE} will simply be ignored.
@end deftypefun
o
@deftypefun int gcry_mpi_get_flag (@w{gcry_mpi_t @var{a}}, @
@w{enum gcry_mpi_flag @var{flag}})
Return true if @var{flag} is set for @var{a}.
@end deftypefun
To put a random value into an MPI, the following convenience function
may be used:
@deftypefun void gcry_mpi_randomize (@w{gcry_mpi_t @var{w}}, @w{unsigned int @var{nbits}}, @w{enum gcry_random_level @var{level}})
Set the multi-precision-integers @var{w} to a random non-negative number of
@var{nbits}, using random data quality of level @var{level}. In case
@var{nbits} is not a multiple of a byte, @var{nbits} is rounded up to
the next byte boundary. When using a @var{level} of
@code{GCRY_WEAK_RANDOM} this function makes use of
@code{gcry_create_nonce}.
@end deftypefun
@c **********************************************************
@c ******************** Prime numbers ***********************
@c **********************************************************
@node Prime numbers
@chapter Prime numbers
@menu
* Generation:: Generation of new prime numbers.
* Checking:: Checking if a given number is prime.
@end menu
@node Generation
@section Generation
@deftypefun gcry_error_t gcry_prime_generate (gcry_mpi_t *@var{prime},unsigned int @var{prime_bits}, unsigned int @var{factor_bits}, gcry_mpi_t **@var{factors}, gcry_prime_check_func_t @var{cb_func}, void *@var{cb_arg}, gcry_random_level_t @var{random_level}, unsigned int @var{flags})
Generate a new prime number of @var{prime_bits} bits and store it in
@var{prime}. If @var{factor_bits} is non-zero, one of the prime factors
of (@var{prime} - 1) / 2 must be @var{factor_bits} bits long. If
@var{factors} is non-zero, allocate a new, @code{NULL}-terminated array
holding the prime factors and store it in @var{factors}. @var{flags}
might be used to influence the prime number generation process.
@end deftypefun
@deftypefun gcry_error_t gcry_prime_group_generator (gcry_mpi_t *@var{r_g}, gcry_mpi_t @var{prime}, gcry_mpi_t *@var{factors}, gcry_mpi_t @var{start_g})
Find a generator for @var{prime} where the factorization of
(@var{prime}-1) is in the @code{NULL} terminated array @var{factors}.
Return the generator as a newly allocated MPI in @var{r_g}. If
@var{start_g} is not NULL, use this as the start for the search.
@end deftypefun
@deftypefun void gcry_prime_release_factors (gcry_mpi_t *@var{factors})
Convenience function to release the @var{factors} array.
@end deftypefun
@node Checking
@section Checking
@deftypefun gcry_error_t gcry_prime_check (gcry_mpi_t @var{p}, unsigned int @var{flags})
Check whether the number @var{p} is prime. Returns zero in case @var{p}
is indeed a prime, returns @code{GPG_ERR_NO_PRIME} in case @var{p} is
not a prime and a different error code in case something went horribly
wrong.
@end deftypefun
@c **********************************************************
@c ******************** Utilities ***************************
@c **********************************************************
@node Utilities
@chapter Utilities
@menu
* Memory allocation:: Functions related with memory allocation.
* Context management:: Functions related with context management.
* Buffer description:: A data type to describe buffers.
* Config reporting:: How to return Libgcrypt's configuration.
@end menu
@node Memory allocation
@section Memory allocation
@deftypefun {void *} gcry_malloc (size_t @var{n})
This function tries to allocate @var{n} bytes of memory. On success
it returns a pointer to the memory area, in an out-of-core condition,
it returns NULL.
@end deftypefun
@deftypefun {void *} gcry_malloc_secure (size_t @var{n})
Like @code{gcry_malloc}, but uses secure memory.
@end deftypefun
@deftypefun {void *} gcry_calloc (size_t @var{n}, size_t @var{m})
This function allocates a cleared block of memory (i.e. initialized with
zero bytes) long enough to contain a vector of @var{n} elements, each of
size @var{m} bytes. On success it returns a pointer to the memory
block; in an out-of-core condition, it returns NULL.
@end deftypefun
@deftypefun {void *} gcry_calloc_secure (size_t @var{n}, size_t @var{m})
Like @code{gcry_calloc}, but uses secure memory.
@end deftypefun
@deftypefun {void *} gcry_realloc (void *@var{p}, size_t @var{n})
This function tries to resize the memory area pointed to by @var{p} to
@var{n} bytes. On success it returns a pointer to the new memory
area, in an out-of-core condition, it returns NULL. Depending on
whether the memory pointed to by @var{p} is secure memory or not,
gcry_realloc tries to use secure memory as well.
@end deftypefun
@deftypefun void gcry_free (void *@var{p})
Release the memory area pointed to by @var{p}.
@end deftypefun
@node Context management
@section Context management
Some function make use of a context object. As of now there are only
a few math functions. However, future versions of Libgcrypt may make
more use of this context object.
@deftp {Data type} {gcry_ctx_t}
This type is used to refer to the general purpose context object.
@end deftp
@anchor{gcry_ctx_release}
@deftypefun void gcry_ctx_release (gcry_ctx_t @var{ctx})
Release the context object @var{ctx} and all associated resources. A
@code{NULL} passed as @var{ctx} is ignored.
@end deftypefun
@node Buffer description
@section Buffer description
To help hashing non-contiguous areas of memory a general purpose data
type is defined:
@deftp {Data type} {gcry_buffer_t}
This type is a structure to describe a buffer. The user should make
sure that this structure is initialized to zero. The available fields
of this structure are:
@table @code
@item .size
This is either 0 for no information available or indicates the
allocated length of the buffer.
@item .off
This is the offset into the buffer.
@item .len
This is the valid length of the buffer starting at @code{.off}.
@item .data
This is the address of the buffer.
@end table
@end deftp
@node Config reporting
@section How to return Libgcrypt's configuration.
Although @code{GCRYCTL_PRINT_CONFIG} can be used to print
configuration options, it is sometimes necessary to check them in a
program. This can be accomplished by using this function:
@deftypefun {char *} gcry_get_config @
(@w{int @var{mode}}, @
@w{const char *@var{what}})
This function returns a malloced string with colon delimited configure
options. With a value of 0 for @var{mode} this string resembles the
output of @code{GCRYCTL_PRINT_CONFIG}. However, if @var{what} is not
NULL, only the line where the first field (e.g. "cpu-arch") matches
@var{what} is returned.
Other values than 0 for @var{mode} are not defined. The caller shall
free the string using @code{gcry_free}. On error NULL is returned and
ERRNO is set; if a value for WHAT is unknow ERRNO will be set to 0.
@end deftypefun
@c **********************************************************
@c ********************* Tools ****************************
@c **********************************************************
@node Tools
@chapter Tools
@menu
* hmac256:: A standalone HMAC-SHA-256 implementation
@end menu
@manpage hmac256.1
@node hmac256
@section A HMAC-SHA-256 tool
@ifset manverb
.B hmac256
\- Compute an HMAC-SHA-256 MAC
@end ifset
@mansect synopsis
@ifset manverb
.B hmac256
.RB [ \-\-binary ]
.I key
.I [FILENAME]
@end ifset
@mansect description
This is a standalone HMAC-SHA-256 implementation used to compute an
HMAC-SHA-256 message authentication code. The tool has originally
been developed as a second implementation for Libgcrypt to allow
comparing against the primary implementation and to be used for
internal consistency checks. It should not be used for sensitive data
because no mechanisms to clear the stack etc are used.
The code has been written in a highly portable manner and requires
only a few standard definitions to be provided in a config.h file.
@noindent
@command{hmac256} is commonly invoked as
@example
hmac256 "This is my key" foo.txt
@end example
@noindent
This compute the MAC on the file @file{foo.txt} using the key given on
the command line.
@mansect options
@noindent
@command{hmac256} understands these options:
@table @gnupgtabopt
@item --binary
Print the MAC as a binary string. The default is to print the MAC
encoded has lower case hex digits.
@item --version
Print version of the program and exit.
@end table
@mansect see also
@ifset isman
@command{sha256sum}(1)
@end ifset
@manpause
@c **********************************************************
@c **************** Environment Variables *****************
@c **********************************************************
@node Configuration
@chapter Configuration files and environment variables
This chapter describes which files and environment variables can be
used to change the behaviour of Libgcrypt.
@noindent
The environment variables considered by Libgcrypt are:
@table @code
@item GCRYPT_BARRETT
@cindex GCRYPT_BARRETT
By setting this variable to any value a different algorithm for
modular reduction is used for ECC.
@item GCRYPT_RNDUNIX_DBG
@item GCRYPT_RNDUNIX_DBGALL
@cindex GCRYPT_RNDUNIX_DBG
@cindex GCRYPT_RNDUNIX_DBGALL
These two environment variables are used to enable debug output for
the rndunix entropy gatherer, which is used on systems lacking a
/dev/random device. The value of @code{GCRYPT_RNDUNIX_DBG} is a file
name or @code{-} for stdout. Debug output is the written to this
file. By setting @code{GCRYPT_RNDUNIX_DBGALL} to any value the debug
output will be more verbose.
@item GCRYPT_RNDW32_NOPERF
@cindex GCRYPT_RNDW32_NOPERF
Setting this environment variable on Windows to any value disables
the use of performance data (@code{HKEY_PERFORMANCE_DATA}) as source
for entropy. On some older Windows systems this could help to speed
up the creation of random numbers but also decreases the amount of
data used to init the random number generator.
@item GCRYPT_RNDW32_DBG
@cindex GCRYPT_RNDW32_DBG
Setting the value of this variable to a positive integer logs
information about the Windows entropy gatherer using the standard log
interface.
@item HOME
@cindex HOME
This is used to locate the socket to connect to the EGD random
daemon. The EGD can be used on system without a /dev/random to speed
up the random number generator. It is not needed on the majority of
today's operating systems and support for EGD requires the use of a
configure option at build time.
@end table
@noindent
The files which Libgcrypt uses to retrieve system information and the
files which can be created by the user to modify Libgcrypt's behavior
are:
@table @file
@item /etc/gcrypt/hwf.deny
@cindex /etc/gcrypt/hwf.deny
This file can be used to disable the use of hardware based
optimizations, @pxref{hardware features}.
@item /etc/gcrypt/random.conf
@cindex /etc/gcrypt/random.conf
This file can be used to globally change parameters of the random
generator. The file is a simple text file where empty lines and
lines with the first non white-space character being '#' are
ignored. Supported options are
@table @file
@item disable-jent
@cindex disable-jent
Disable the use of the jitter based entropy generator.
@item only-urandom
@cindex only-urandom
Always use the non-blocking /dev/urandom or the respective system call
instead of the blocking /dev/random. If Libgcrypt is used early in
the boot process of the system, this option should only be used if the
system also supports the getrandom system call.
@end table
@item /etc/gcrypt/fips_enabled
@itemx /proc/sys/crypto/fips_enabled
@cindex /etc/gcrypt/fips_enabled
@cindex fips_enabled
On Linux these files are used to enable FIPS mode, @pxref{enabling fips mode}.
@item /proc/cpuinfo
@itemx /proc/self/auxv
@cindex /proc/cpuinfo
@cindex /proc/self/auxv
On Linux running on the ARM architecture, these files are used to read
hardware capabilities of the CPU.
@end table
@c **********************************************************
@c ***************** Architecure Overview *****************
@c **********************************************************
@node Architecture
@chapter Architecture
This chapter describes the internal architecture of Libgcrypt.
Libgcrypt is a function library written in ISO C-90. Any compliant
compiler should be able to build Libgcrypt as long as the target is
either a POSIX platform or compatible to the API used by Windows NT.
Provisions have been take so that the library can be directly used from
C++ applications; however building with a C++ compiler is not supported.
Building Libgcrypt is done by using the common @code{./configure && make}
approach. The configure command is included in the source distribution
and as a portable shell script it works on any Unix-alike system. The
result of running the configure script are a C header file
(@file{config.h}), customized Makefiles, the setup of symbolic links and
a few other things. After that the make tool builds and optionally
installs the library and the documentation. See the files
@file{INSTALL} and @file{README} in the source distribution on how to do
this.
Libgcrypt is developed using a Subversion@footnote{A version control
system available for many platforms} repository. Although all released
versions are tagged in this repository, they should not be used to build
production versions of Libgcrypt. Instead released tarballs should be
used. These tarballs are available from several places with the master
copy at @indicateurl{ftp://ftp.gnupg.org/gcrypt/libgcrypt/}.
Announcements of new releases are posted to the
@indicateurl{gnupg-announce@@gnupg.org} mailing list@footnote{See
@url{http://www.gnupg.org/documentation/mailing-lists.en.html} for
details.}.
@float Figure,fig:subsystems
@caption{Libgcrypt subsystems}
@center @image{libgcrypt-modules, 150mm,,Libgcrypt subsystems}
@end float
Libgcrypt consists of several subsystems (@pxref{fig:subsystems}) and
all these subsystems provide a public API; this includes the helper
subsystems like the one for S-expressions. The API style depends on the
subsystem; in general an open-use-close approach is implemented. The
open returns a handle to a context used for all further operations on
this handle, several functions may then be used on this handle and a
final close function releases all resources associated with the handle.
@menu
* Public-Key Subsystem Architecture:: About public keys.
* Symmetric Encryption Subsystem Architecture:: About standard ciphers.
* Hashing and MACing Subsystem Architecture:: About hashing.
* Multi-Precision-Integer Subsystem Architecture:: About big integers.
* Prime-Number-Generator Subsystem Architecture:: About prime numbers.
* Random-Number Subsystem Architecture:: About random stuff.
@c * Helper Subsystems Architecture:: About other stuff.
@end menu
@node Public-Key Subsystem Architecture
@section Public-Key Architecture
Because public key cryptography is almost always used to process small
amounts of data (hash values or session keys), the interface is not
implemented using the open-use-close paradigm, but with single
self-contained functions. Due to the wide variety of parameters
required by different algorithms S-expressions, as flexible way to
convey these parameters, are used. There is a set of helper functions
to work with these S-expressions.
@c see @xref{S-expression Subsystem Architecture}.
Aside of functions to register new algorithms, map algorithms names to
algorithms identifiers and to lookup properties of a key, the
following main functions are available:
@table @code
@item gcry_pk_encrypt
Encrypt data using a public key.
@item gcry_pk_decrypt
Decrypt data using a private key.
@item gcry_pk_sign
Sign data using a private key.
@item gcry_pk_verify
Verify that a signature matches the data.
@item gcry_pk_testkey
Perform a consistency over a public or private key.
@item gcry_pk_genkey
Create a new public/private key pair.
@end table
All these functions
lookup the module implementing the algorithm and pass the actual work
to that module. The parsing of the S-expression input and the
construction of S-expression for the return values is done by the high
level code (@file{cipher/pubkey.c}). Thus the internal interface
between the algorithm modules and the high level functions passes data
in a custom format.
By default Libgcrypt uses a blinding technique for RSA decryption to
mitigate real world timing attacks over a network: Instead of using
the RSA decryption directly, a blinded value @math{y = x r^{e} \bmod n}
is decrypted and the unblinded value @math{x' = y' r^{-1} \bmod n}
returned. The blinding value @math{r} is a random value with the size
of the modulus @math{n} and generated with @code{GCRY_WEAK_RANDOM}
random level.
@cindex X9.31
@cindex FIPS 186
The algorithm used for RSA and DSA key generation depends on whether
Libgcrypt is operated in standard or in FIPS mode. In standard mode
an algorithm based on the Lim-Lee prime number generator is used. In
FIPS mode RSA keys are generated as specified in ANSI X9.31 (1998) and
DSA keys as specified in FIPS 186-2.
@node Symmetric Encryption Subsystem Architecture
@section Symmetric Encryption Subsystem Architecture
The interface to work with symmetric encryption algorithms is made up
of functions from the @code{gcry_cipher_} name space. The
implementation follows the open-use-close paradigm and uses registered
algorithm modules for the actual work. Unless a module implements
optimized cipher mode implementations, the high level code
(@file{cipher/cipher.c}) implements the modes and calls the core
algorithm functions to process each block.
The most important functions are:
@table @code
@item gcry_cipher_open
Create a new instance to encrypt or decrypt using a specified
algorithm and mode.
@item gcry_cipher_close
Release an instance.
@item gcry_cipher_setkey
Set a key to be used for encryption or decryption.
@item gcry_cipher_setiv
Set an initialization vector to be used for encryption or decryption.
@item gcry_cipher_encrypt
@itemx gcry_cipher_decrypt
Encrypt or decrypt data. These functions may be called with arbitrary
amounts of data and as often as needed to encrypt or decrypt all data.
@end table
There are also functions to query properties of algorithms or context,
like block length, key length, map names or to enable features like
padding methods.
@node Hashing and MACing Subsystem Architecture
@section Hashing and MACing Subsystem Architecture
The interface to work with message digests and CRC algorithms is made
up of functions from the @code{gcry_md_} name space. The
implementation follows the open-use-close paradigm and uses registered
algorithm modules for the actual work. Although CRC algorithms are
not considered cryptographic hash algorithms, they share enough
properties so that it makes sense to handle them in the same way.
It is possible to use several algorithms at once with one context and
thus compute them all on the same data.
The most important functions are:
@table @code
@item gcry_md_open
Create a new message digest instance and optionally enable one
algorithm. A flag may be used to turn the message digest algorithm
into a HMAC algorithm.
@item gcry_md_enable
Enable an additional algorithm for the instance.
@item gcry_md_setkey
Set the key for the MAC.
@item gcry_md_write
Pass more data for computing the message digest to an instance.
@item gcry_md_putc
Buffered version of @code{gcry_md_write} implemented as a macro.
@item gcry_md_read
Finalize the computation of the message digest or HMAC and return the
result.
@item gcry_md_close
Release an instance
@item gcry_md_hash_buffer
Convenience function to directly compute a message digest over a
memory buffer without the need to create an instance first.
@end table
There are also functions to query properties of algorithms or the
instance, like enabled algorithms, digest length, map algorithm names.
it is also possible to reset an instance or to copy the current state
of an instance at any time. Debug functions to write the hashed data
to files are available as well.
@node Multi-Precision-Integer Subsystem Architecture
@section Multi-Precision-Integer Subsystem Architecture
The implementation of Libgcrypt's big integer computation code is
based on an old release of GNU Multi-Precision Library (GMP). The
decision not to use the GMP library directly was due to stalled
development at that time and due to security requirements which could
not be provided by the code in GMP. As GMP does, Libgcrypt provides
high performance assembler implementations of low level code for
several CPUS to gain much better performance than with a generic C
implementation.
@noindent
Major features of Libgcrypt's multi-precision-integer code compared to
GMP are:
@itemize
@item
Avoidance of stack based allocations to allow protection against
swapping out of sensitive data and for easy zeroing of sensitive
intermediate results.
@item
Optional use of secure memory and tracking of its use so that results
are also put into secure memory.
@item
MPIs are identified by a handle (implemented as a pointer) to give
better control over allocations and to augment them with extra
properties like opaque data.
@item
Removal of unnecessary code to reduce complexity.
@item
Functions specialized for public key cryptography.
@end itemize
@node Prime-Number-Generator Subsystem Architecture
@section Prime-Number-Generator Subsystem Architecture
Libgcrypt provides an interface to its prime number generator. These
functions make use of the internal prime number generator which is
required for the generation for public key key pairs. The plain prime
checking function is exported as well.
The generation of random prime numbers is based on the Lim and Lee
algorithm to create practically save primes.@footnote{Chae Hoon Lim
and Pil Joong Lee. A key recovery attack on discrete log-based schemes
using a prime order subgroup. In Burton S. Kaliski Jr., editor,
Advances in Cryptology: Crypto '97, pages 249­-263, Berlin /
Heidelberg / New York, 1997. Springer-Verlag. Described on page 260.}
This algorithm creates a pool of smaller primes, select a few of them
to create candidate primes of the form @math{2 * p_0 * p_1 * ... * p_n
+ 1}, tests the candidate for primality and permutates the pool until
a prime has been found. It is possible to clamp one of the small
primes to a certain size to help DSA style algorithms. Because most
of the small primes in the pool are not used for the resulting prime
number, they are saved for later use (see @code{save_pool_prime} and
@code{get_pool_prime} in @file{cipher/primegen.c}). The prime
generator optionally supports the finding of an appropriate generator.
@noindent
The primality test works in three steps:
@enumerate
@item
The standard sieve algorithm using the primes up to 4999 is used as a
quick first check.
@item
A Fermat test filters out almost all non-primes.
@item
A 5 round Rabin-Miller test is finally used. The first round uses a
witness of 2, whereas the next rounds use a random witness.
@end enumerate
To support the generation of RSA and DSA keys in FIPS mode according
to X9.31 and FIPS 186-2, Libgcrypt implements two additional prime
generation functions: @code{_gcry_derive_x931_prime} and
@code{_gcry_generate_fips186_2_prime}. These functions are internal
and not available through the public API.
@node Random-Number Subsystem Architecture
@section Random-Number Subsystem Architecture
Libgcrypt provides 3 levels or random quality: The level
@code{GCRY_VERY_STRONG_RANDOM} usually used for key generation, the
level @code{GCRY_STRONG_RANDOM} for all other strong random
requirements and the function @code{gcry_create_nonce} which is used
for weaker usages like nonces. There is also a level
@code{GCRY_WEAK_RANDOM} which in general maps to
@code{GCRY_STRONG_RANDOM} except when used with the function
@code{gcry_mpi_randomize}, where it randomizes an
multi-precision-integer using the @code{gcry_create_nonce} function.
@noindent
There are two distinct random generators available:
@itemize
@item
The Continuously Seeded Pseudo Random Number Generator (CSPRNG), which
is based on the classic GnuPG derived big pool implementation.
Implemented in @code{random/random-csprng.c} and used by default.
@item
A FIPS approved ANSI X9.31 PRNG using AES with a 128 bit key. Implemented in
@code{random/random-fips.c} and used if Libgcrypt is in FIPS mode.
@end itemize
@noindent
Both generators make use of so-called entropy gathering modules:
@table @asis
@item rndlinux
Uses the operating system provided @file{/dev/random} and
@file{/dev/urandom} devices. The @file{/dev/gcrypt/random.conf}
config option @option{only-urandom} can be used to inhibit the use of
the blocking @file{/dev/random} device.
@item rndunix
Runs several operating system commands to collect entropy from sources
like virtual machine and process statistics. It is a kind of
poor-man's @code{/dev/random} implementation. It is not available in
FIPS mode.
@item rndegd
Uses the operating system provided Entropy Gathering Daemon (EGD).
The EGD basically uses the same algorithms as rndunix does. However
as a system daemon it keeps on running and thus can serve several
processes requiring entropy input and does not waste collected entropy
if the application does not need all the collected entropy. It is not
available in FIPS mode.
@item rndw32
Targeted for the Microsoft Windows OS. It uses certain properties of
that system and is the only gathering module available for that OS.
@item rndhw
Extra module to collect additional entropy by utilizing a hardware
random number generator. As of now the supported hardware RNG is
the Padlock engine of VIA (Centaur) CPUs and x86 CPUs with the RDRAND
instruction. It is not available in FIPS mode.
@item rndjent
Extra module to collect additional entropy using a CPU jitter based
approach. This is only used on X86 hardware where the RDTSC opcode is
available. The @file{/dev/gcrypt/random.conf} config option
@option{disable-jent} can be used to inhibit the use of this module.
@end table
@menu
* CSPRNG Description:: Description of the CSPRNG.
* FIPS PRNG Description:: Description of the FIPS X9.31 PRNG.
@end menu
@node CSPRNG Description
@subsection Description of the CSPRNG
This random number generator is loosely modelled after the one
described in Peter Gutmann's paper: "Software Generation of
Practically Strong Random Numbers".@footnote{Also described in chapter
6 of his book "Cryptographic Security Architecture", New York, 2004,
ISBN 0-387-95387-6.}
A pool of 600 bytes is used and mixed using the core SHA-1 hash
transform function. Several extra features are used to make the
robust against a wide variety of attacks and to protect against
failures of subsystems. The state of the generator may be saved to a
file and initially seed form a file.
Depending on how Libgcrypt was build the generator is able to select
the best working entropy gathering module. It makes use of the slow
and fast collection methods and requires the pool to initially seeded
form the slow gatherer or a seed file. An entropy estimation is used
to mix in enough data from the gather modules before returning the
actual random output. Process fork detection and protection is
implemented.
@c FIXME: The design and implementation needs a more verbose description.
The implementation of the nonce generator (for
@code{gcry_create_nonce}) is a straightforward repeated hash design: A
28 byte buffer is initially seeded with the PID and the time in
seconds in the first 20 bytes and with 8 bytes of random taken from
the @code{GCRY_STRONG_RANDOM} generator. Random numbers are then
created by hashing all the 28 bytes with SHA-1 and saving that again
in the first 20 bytes. The hash is also returned as result.
@node FIPS PRNG Description
@subsection Description of the FIPS X9.31 PRNG
The core of this deterministic random number generator is implemented
according to the document ``NIST-Recommended Random Number Generator
Based on ANSI X9.31 Appendix A.2.4 Using the 3-Key Triple DES and AES
Algorithms'', dated 2005-01-31. This implementation uses the AES
variant.
The generator is based on contexts to utilize the same core functions
for all random levels as required by the high-level interface. All
random generators return their data in 128 bit blocks. If the caller
requests less bits, the extra bits are not used. The key for each
generator is only set once at the first time a generator context is
used. The seed value is set along with the key and again after 1000
output blocks.
On Unix like systems the @code{GCRY_VERY_STRONG_RANDOM} and
@code{GCRY_STRONG_RANDOM} generators are keyed and seeded using the
rndlinux module with the @file{/dev/random} device. Thus these
generators may block until the OS kernel has collected enough entropy.
When used with Microsoft Windows the rndw32 module is used instead.
The generator used for @code{gcry_create_nonce} is keyed and seeded
from the @code{GCRY_STRONG_RANDOM} generator. Thus is may also block
if the @code{GCRY_STRONG_RANDOM} generator has not yet been used
before and thus gets initialized on the first use by
@code{gcry_create_nonce}. This special treatment is justified by the
weaker requirements for a nonce generator and to save precious kernel
entropy for use by the ``real'' random generators.
A self-test facility uses a separate context to check the
functionality of the core X9.31 functions using a known answers test.
During runtime each output block is compared to the previous one to
detect a stuck generator.
The DT value for the generator is made up of the current time down to
microseconds (if available) and a free running 64 bit counter. When
used with the test context the DT value is taken from the context and
incremented on each use.
@c @node Helper Subsystems Architecture
@c @section Helper Subsystems Architecture
@c
@c There are a few smaller subsystems which are mainly used internally by
@c Libgcrypt but also available to applications.
@c
@c @menu
@c * S-expression Subsystem Architecture:: Details about the S-expression architecture.
@c * Memory Subsystem Architecture:: Details about the memory allocation architecture.
@c * Miscellaneous Subsystems Architecture:: Details about other subsystems.
@c @end menu
@c
@c @node S-expression Subsystem Architecture
@c @subsection S-expression Subsystem Architecture
@c
@c Libgcrypt provides an interface to S-expression to create and parse
@c them. To use an S-expression with Libgcrypt it needs first be
@c converted into the internal representation used by Libgcrypt (the type
@c @code{gcry_sexp_t}). The conversion functions support a large subset
@c of the S-expression specification and further feature a printf like
@c function to convert a list of big integers or other binary data into
@c an S-expression.
@c
@c Libgcrypt currently implements S-expressions using a tagged linked
@c list. However this is not exposed to an application and may be
@c changed in future releases to reduce overhead when already working
@c with canonically encoded S-expressions. Secure memory is supported by
@c this S-expressions implementation.
@c
@c @node Memory Subsystem Architecture
@c @subsection Memory Subsystem Architecture
@c
@c TBD.
@c
@c
@c @node Miscellaneous Subsystems Architecture
@c @subsection Miscellaneous Subsystems Architecture
@c
@c TBD.
@c
@c
@c **********************************************************
@c ******************* Appendices *************************
@c **********************************************************
@c ********************************************
@node Self-Tests
@appendix Description of the Self-Tests
In addition to the build time regression test suite, Libgcrypt
implements self-tests to be performed at runtime. Which self-tests
are actually used depends on the mode Libgcrypt is used in. In
standard mode a limited set of self-tests is run at the time an
algorithm is first used. Note that not all algorithms feature a
self-test in standard mode. The @code{GCRYCTL_SELFTEST} control
command may be used to run all implemented self-tests at any time;
this will even run more tests than those run in FIPS mode.
If any of the self-tests fails, the library immediately returns an
error code to the caller. If Libgcrypt is in FIPS mode the self-tests
will be performed within the ``Self-Test'' state and any failure puts
the library into the ``Error'' state.
@c --------------------------------
@section Power-Up Tests
Power-up tests are only performed if Libgcrypt is in FIPS mode.
@subsection Symmetric Cipher Algorithm Power-Up Tests
The following symmetric encryption algorithm tests are run during
power-up:
@table @asis
@item 3DES
To test the 3DES 3-key EDE encryption in ECB mode these tests are
run:
@enumerate
@item
A known answer test is run on a 64 bit test vector processed by 64
rounds of Single-DES block encryption and decryption using a key
changed with each round.
@item
A known answer test is run on a 64 bit test vector processed by 16
rounds of 2-key and 3-key Triple-DES block encryption and decryptions
using a key changed with each round.
@item
10 known answer tests using 3-key Triple-DES EDE encryption, comparing
the ciphertext to the known value, then running a decryption and
comparing it to the initial plaintext.
@end enumerate
(@code{cipher/des.c:selftest})
@item AES-128
A known answer tests is run using one test vector and one test
key with AES in ECB mode. (@code{cipher/rijndael.c:selftest_basic_128})
@item AES-192
A known answer tests is run using one test vector and one test
key with AES in ECB mode. (@code{cipher/rijndael.c:selftest_basic_192})
@item AES-256
A known answer tests is run using one test vector and one test key
with AES in ECB mode. (@code{cipher/rijndael.c:selftest_basic_256})
@end table
@subsection Hash Algorithm Power-Up Tests
The following hash algorithm tests are run during power-up:
@table @asis
@item SHA-1
A known answer test using the string @code{"abc"} is run.
(@code{cipher/@/sha1.c:@/selftests_sha1})
@item SHA-224
A known answer test using the string @code{"abc"} is run.
(@code{cipher/@/sha256.c:@/selftests_sha224})
@item SHA-256
A known answer test using the string @code{"abc"} is run.
(@code{cipher/@/sha256.c:@/selftests_sha256})
@item SHA-384
A known answer test using the string @code{"abc"} is run.
(@code{cipher/@/sha512.c:@/selftests_sha384})
@item SHA-512
A known answer test using the string @code{"abc"} is run.
(@code{cipher/@/sha512.c:@/selftests_sha512})
@end table
@subsection MAC Algorithm Power-Up Tests
The following MAC algorithm tests are run during power-up:
@table @asis
@item HMAC SHA-1
A known answer test using 9 byte of data and a 64 byte key is run.
(@code{cipher/hmac-tests.c:selftests_sha1})
@item HMAC SHA-224
A known answer test using 28 byte of data and a 4 byte key is run.
(@code{cipher/hmac-tests.c:selftests_sha224})
@item HMAC SHA-256
A known answer test using 28 byte of data and a 4 byte key is run.
(@code{cipher/hmac-tests.c:selftests_sha256})
@item HMAC SHA-384
A known answer test using 28 byte of data and a 4 byte key is run.
(@code{cipher/hmac-tests.c:selftests_sha384})
@item HMAC SHA-512
A known answer test using 28 byte of data and a 4 byte key is run.
(@code{cipher/hmac-tests.c:selftests_sha512})
@end table
@subsection Random Number Power-Up Test
The DRNG is tested during power-up this way:
@enumerate
@item
Requesting one block of random using the public interface to check
general working and the duplicated block detection.
@item
3 know answer tests using pre-defined keys, seed and initial DT
values. For each test 3 blocks of 16 bytes are requested and compared
to the expected result. The DT value is incremented for each block.
@end enumerate
@subsection Public Key Algorithm Power-Up Tests
The public key algorithms are tested during power-up:
@table @asis
@item RSA
A pre-defined 1024 bit RSA key is used and these tests are run
in turn:
@enumerate
@item
Conversion of S-expression to internal format.
(@code{cipher/@/rsa.c:@/selftests_rsa})
@item
Private key consistency check.
(@code{cipher/@/rsa.c:@/selftests_rsa})
@item
A pre-defined 20 byte value is signed with PKCS#1 padding for SHA-1.
The result is verified using the public key against the original data
and against modified data. (@code{cipher/@/rsa.c:@/selftest_sign_1024})
@item
A 1000 bit random value is encrypted and checked that it does not
match the original random value. The encrypted result is then
decrypted and checked that it matches the original random value.
(@code{cipher/@/rsa.c:@/selftest_encr_1024})
@end enumerate
@item DSA
A pre-defined 1024 bit DSA key is used and these tests are run in turn:
@enumerate
@item
Conversion of S-expression to internal format.
(@code{cipher/@/dsa.c:@/selftests_dsa})
@item
Private key consistency check.
(@code{cipher/@/dsa.c:@/selftests_dsa})
@item
A pre-defined 20 byte value is signed with PKCS#1 padding for
SHA-1. The result is verified using the public key against the
original data and against modified data.
(@code{cipher/@/dsa.c:@/selftest_sign_1024})
@end enumerate
@end table
@subsection Integrity Power-Up Tests
The integrity of the Libgcrypt is tested during power-up but only if
checking has been enabled at build time. The check works by computing
a HMAC SHA-256 checksum over the file used to load Libgcrypt into
memory. That checksum is compared against a checksum stored in a file
of the same name but with a single dot as a prefix and a suffix of
@file{.hmac}.
@subsection Critical Functions Power-Up Tests
The 3DES weak key detection is tested during power-up by calling the
detection function with keys taken from a table listening all weak
keys. The table itself is protected using a SHA-1 hash.
(@code{cipher/@/des.c:@/selftest})
@c --------------------------------
@section Conditional Tests
The conditional tests are performed if a certain condition is met.
This may occur at any time; the library does not necessary enter the
``Self-Test'' state to run these tests but will transit to the
``Error'' state if a test failed.
@subsection Key-Pair Generation Tests
After an asymmetric key-pair has been generated, Libgcrypt runs a
pair-wise consistency tests on the generated key. On failure the
generated key is not used, an error code is returned and, if in FIPS
mode, the library is put into the ``Error'' state.
@table @asis
@item RSA
The test uses a random number 64 bits less the size of the modulus as
plaintext and runs an encryption and decryption operation in turn. The
encrypted value is checked to not match the plaintext and the result
of the decryption is checked to match the plaintext.
A new random number of the same size is generated, signed and verified
to test the correctness of the signing operation. As a second signing
test, the signature is modified by incrementing its value and then
verified with the expected result that the verification fails.
(@code{cipher/@/rsa.c:@/test_keys})
@item DSA
The test uses a random number of the size of the Q parameter to create
a signature and then checks that the signature verifies. As a second
signing test, the data is modified by incrementing its value and then
verified against the signature with the expected result that the
verification fails. (@code{cipher/@/dsa.c:@/test_keys})
@end table
@subsection Software Load Tests
No code is loaded at runtime.
@subsection Manual Key Entry Tests
A manual key entry feature is not implemented in Libgcrypt.
@subsection Continuous RNG Tests
The continuous random number test is only used in FIPS mode. The RNG
generates blocks of 128 bit size; the first block generated per
context is saved in the context and another block is generated to be
returned to the caller. Each block is compared against the saved
block and then stored in the context. If a duplicated block is
detected an error is signaled and the library is put into the
``Fatal-Error'' state.
(@code{random/@/random-fips.c:@/x931_aes_driver})
@c --------------------------------
@section Application Requested Tests
The application may requests tests at any time by means of the
@code{GCRYCTL_SELFTEST} control command. Note that using these tests
is not FIPS conform: Although Libgcrypt rejects all application
requests for services while running self-tests, it does not ensure
that no other operations of Libgcrypt are still being executed. Thus,
in FIPS mode an application requesting self-tests needs to power-cycle
Libgcrypt instead.
When self-tests are requested, Libgcrypt runs all the tests it does
during power-up as well as a few extra checks as described below.
@subsection Symmetric Cipher Algorithm Tests
The following symmetric encryption algorithm tests are run in addition
to the power-up tests:
@table @asis
@item AES-128
A known answer tests with test vectors taken from NIST SP800-38a and
using the high level functions is run for block modes CFB and OFB.
@end table
@subsection Hash Algorithm Tests
The following hash algorithm tests are run in addition to the
power-up tests:
@table @asis
@item SHA-1
@itemx SHA-224
@itemx SHA-256
@enumerate
@item
A known answer test using a 56 byte string is run.
@item
A known answer test using a string of one million letters "a" is run.
@end enumerate
(@code{cipher/@/sha1.c:@/selftests_sha1},
@code{cipher/@/sha256.c:@/selftests_sha224},
@code{cipher/@/sha256.c:@/selftests_sha256})
@item SHA-384
@item SHA-512
@enumerate
@item
A known answer test using a 112 byte string is run.
@item
A known answer test using a string of one million letters "a" is run.
@end enumerate
(@code{cipher/@/sha512.c:@/selftests_sha384},
@code{cipher/@/sha512.c:@/selftests_sha512})
@end table
@subsection MAC Algorithm Tests
The following MAC algorithm tests are run in addition to the power-up
tests:
@table @asis
@item HMAC SHA-1
@enumerate
@item
A known answer test using 9 byte of data and a 20 byte key is run.
@item
A known answer test using 9 byte of data and a 100 byte key is run.
@item
A known answer test using 9 byte of data and a 49 byte key is run.
@end enumerate
(@code{cipher/hmac-tests.c:selftests_sha1})
@item HMAC SHA-224
@itemx HMAC SHA-256
@itemx HMAC SHA-384
@itemx HMAC SHA-512
@enumerate
@item
A known answer test using 9 byte of data and a 20 byte key is run.
@item
A known answer test using 50 byte of data and a 20 byte key is run.
@item
A known answer test using 50 byte of data and a 26 byte key is run.
@item
A known answer test using 54 byte of data and a 131 byte key is run.
@item
A known answer test using 152 byte of data and a 131 byte key is run.
@end enumerate
(@code{cipher/@/hmac-tests.c:@/selftests_sha224},
@code{cipher/@/hmac-tests.c:@/selftests_sha256},
@code{cipher/@/hmac-tests.c:@/selftests_sha384},
@code{cipher/@/hmac-tests.c:@/selftests_sha512})
@end table
@c ********************************************
@node FIPS Mode
@appendix Description of the FIPS Mode
This appendix gives detailed information pertaining to the FIPS mode.
In particular, the changes to the standard mode and the finite state
machine are described. The self-tests required in this mode are
described in the appendix on self-tests.
@c -------------------------------
@section Restrictions in FIPS Mode
@noindent
If Libgcrypt is used in FIPS mode these restrictions are effective:
@itemize
@item
The cryptographic algorithms are restricted to this list:
@table @asis
@item GCRY_CIPHER_3DES
3 key EDE Triple-DES symmetric encryption.
@item GCRY_CIPHER_AES128
AES 128 bit symmetric encryption.
@item GCRY_CIPHER_AES192
AES 192 bit symmetric encryption.
@item GCRY_CIPHER_AES256
AES 256 bit symmetric encryption.
@item GCRY_MD_SHA1
SHA-1 message digest.
@item GCRY_MD_SHA224
SHA-224 message digest.
@item GCRY_MD_SHA256
SHA-256 message digest.
@item GCRY_MD_SHA384
SHA-384 message digest.
@item GCRY_MD_SHA512
SHA-512 message digest.
@item GCRY_MD_SHA1,GCRY_MD_FLAG_HMAC
HMAC using a SHA-1 message digest.
@item GCRY_MD_SHA224,GCRY_MD_FLAG_HMAC
HMAC using a SHA-224 message digest.
@item GCRY_MD_SHA256,GCRY_MD_FLAG_HMAC
HMAC using a SHA-256 message digest.
@item GCRY_MD_SHA384,GCRY_MD_FLAG_HMAC
HMAC using a SHA-384 message digest.
@item GCRY_MD_SHA512,GCRY_MD_FLAG_HMAC
HMAC using a SHA-512 message digest.
@item GCRY_PK_RSA
RSA encryption and signing.
@item GCRY_PK_DSA
DSA signing.
@end table
Note that the CRC algorithms are not considered cryptographic algorithms
and thus are in addition available.
@item
RSA key generation refuses to create a key with a keysize of
less than 1024 bits.
@item
DSA key generation refuses to create a key with a keysize other
than 1024 bits.
@item
The @code{transient-key} flag for RSA and DSA key generation is ignored.
@item
Support for the VIA Padlock engine is disabled.
@item
FIPS mode may only be used on systems with a /dev/random device.
Switching into FIPS mode on other systems will fail at runtime.
@item
Saving and loading a random seed file is ignored.
@item
An X9.31 style random number generator is used in place of the
large-pool-CSPRNG generator.
@item
The command @code{GCRYCTL_ENABLE_QUICK_RANDOM} is ignored.
@item
Message digest debugging is disabled.
@item
All debug output related to cryptographic data is suppressed.
@item
On-the-fly self-tests are not performed, instead self-tests are run
before entering operational state.
@item
The function @code{gcry_set_allocation_handler} may not be used. If
it is used Libgcrypt disables FIPS mode unless Enforced FIPS mode is
enabled, in which case Libgcrypt will enter the error state.
@item
The digest algorithm MD5 may not be used. If it is used Libgcrypt
disables FIPS mode unless Enforced FIPS mode is enabled, in which case
Libgcrypt will enter the error state.
@item
In Enforced FIPS mode the command @code{GCRYCTL_DISABLE_SECMEM} is
ignored. In standard FIPS mode it disables FIPS mode.
@item
A handler set by @code{gcry_set_outofcore_handler} is ignored.
@item
A handler set by @code{gcry_set_fatalerror_handler} is ignored.
@end itemize
Note that when we speak about disabling FIPS mode, it merely means
that the function @code{gcry_fips_mode_active} returns false; it does
not mean that any non FIPS algorithms are allowed.
@c ********************************************
@section FIPS Finite State Machine
The FIPS mode of libgcrypt implements a finite state machine (FSM) using
8 states (@pxref{tbl:fips-states}) and checks at runtime that only valid
transitions (@pxref{tbl:fips-state-transitions}) may happen.
@float Figure,fig:fips-fsm
@caption{FIPS mode state diagram}
@center @image{fips-fsm,150mm,,FIPS FSM Diagram}
@end float
@float Table,tbl:fips-states
@caption{FIPS mode states}
@noindent
States used by the FIPS FSM:
@table @asis
@item Power-Off
Libgcrypt is not runtime linked to another application. This usually
means that the library is not loaded into main memory. This state is
documentation only.
@item Power-On
Libgcrypt is loaded into memory and API calls may be made. Compiler
introduced constructor functions may be run. Note that Libgcrypt does
not implement any arbitrary constructor functions to be called by the
operating system
@item Init
The Libgcrypt initialization functions are performed and the library has
not yet run any self-test.
@item Self-Test
Libgcrypt is performing self-tests.
@item Operational
Libgcrypt is in the operational state and all interfaces may be used.
@item Error
Libgrypt is in the error state. When calling any FIPS relevant
interfaces they either return an error (@code{GPG_ERR_NOT_OPERATIONAL})
or put Libgcrypt into the Fatal-Error state and won't return.
@item Fatal-Error
Libgcrypt is in a non-recoverable error state and
will automatically transit into the Shutdown state.
@item Shutdown
Libgcrypt is about to be terminated and removed from the memory. The
application may at this point still running cleanup handlers.
@end table
@end float
@float Table,tbl:fips-state-transitions
@caption{FIPS mode state transitions}
@noindent
The valid state transitions (@pxref{fig:fips-fsm}) are:
@table @code
@item 1
Power-Off to Power-On is implicitly done by the OS loading Libgcrypt as
a shared library and having it linked to an application.
@item 2
Power-On to Init is triggered by the application calling the
Libgcrypt initialization function @code{gcry_check_version}.
@item 3
Init to Self-Test is either triggered by a dedicated API call or implicit
by invoking a libgrypt service controlled by the FSM.
@item 4
Self-Test to Operational is triggered after all self-tests passed
successfully.
@item 5
Operational to Shutdown is an artificial state without any direct action
in Libgcrypt. When reaching the Shutdown state the library is
deinitialized and can't return to any other state again.
@item 6
Shutdown to Power-off is the process of removing Libgcrypt from the
computer's memory. For obvious reasons the Power-Off state can't be
represented within Libgcrypt and thus this transition is for
documentation only.
@item 7
Operational to Error is triggered if Libgcrypt detected an application
error which can't be returned to the caller but still allows Libgcrypt
to properly run. In the Error state all FIPS relevant interfaces return
an error code.
@item 8
Error to Shutdown is similar to the Operational to Shutdown transition
(5).
@item 9
Error to Fatal-Error is triggered if Libgrypt detects an fatal error
while already being in Error state.
@item 10
Fatal-Error to Shutdown is automatically entered by Libgcrypt
after having reported the error.
@item 11
Power-On to Shutdown is an artificial state to document that Libgcrypt
has not ye been initialized but the process is about to terminate.
@item 12
Power-On to Fatal-Error will be triggered if certain Libgcrypt functions
are used without having reached the Init state.
@item 13
Self-Test to Fatal-Error is triggered by severe errors in Libgcrypt while
running self-tests.
@item 14
Self-Test to Error is triggered by a failed self-test.
@item 15
Operational to Fatal-Error is triggered if Libcrypt encountered a
non-recoverable error.
@item 16
Operational to Self-Test is triggered if the application requested to run
the self-tests again.
@item 17
Error to Self-Test is triggered if the application has requested to run
self-tests to get to get back into operational state after an error.
@item 18
Init to Error is triggered by errors in the initialization code.
@item 19
Init to Fatal-Error is triggered by non-recoverable errors in the
initialization code.
@item 20
Error to Error is triggered by errors while already in the Error
state.
@end table
@end float
@c ********************************************
@section FIPS Miscellaneous Information
Libgcrypt does not do any key management on itself; the application
needs to care about it. Keys which are passed to Libgcrypt should be
allocated in secure memory as available with the functions
@code{gcry_malloc_secure} and @code{gcry_calloc_secure}. By calling
@code{gcry_free} on this memory, the memory and thus the keys are
overwritten with zero bytes before releasing the memory.
For use with the random number generator, Libgcrypt generates 3
internal keys which are stored in the encryption contexts used by the
RNG. These keys are stored in secure memory for the lifetime of the
process. Application are required to use @code{GCRYCTL_TERM_SECMEM}
before process termination. This will zero out the entire secure
memory and thus also the encryption contexts with these keys.
@c **********************************************************
@c ************* Appendices (license etc.) ****************
@c **********************************************************
@include lgpl.texi
@include gpl.texi
@node Figures and Tables
@unnumbered List of Figures and Tables
@listoffloats Figure
@listoffloats Table
@node Concept Index
@unnumbered Concept Index
@printindex cp
@node Function and Data Index
@unnumbered Function and Data Index
@printindex fn
@bye
GCRYCTL_SET_RANDOM_DAEMON_SOCKET
GCRYCTL_USE_RANDOM_DAEMON
The random daemon is still a bit experimental, thus we do not document
them. Note that they should be used during initialization and that
these functions are not really thread safe.
@c LocalWords: int HD
diff --git a/src/gcrypt.h.in b/src/gcrypt.h.in
index b55657f5..1eb3d7c0 100644
--- a/src/gcrypt.h.in
+++ b/src/gcrypt.h.in
@@ -1,1803 +1,1804 @@
/* gcrypt.h - GNU Cryptographic Library Interface -*- c -*-
* Copyright (C) 1998-2017 Free Software Foundation, Inc.
* Copyright (C) 2012-2017 g10 Code GmbH
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, see <http://www.gnu.org/licenses/>.
*
* File: @configure_input@
*/
#ifndef _GCRYPT_H
#define _GCRYPT_H
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <gpg-error.h>
#include <sys/types.h>
#if defined _WIN32 || defined __WIN32__
# include <winsock2.h>
# include <ws2tcpip.h>
# include <time.h>
# ifndef __GNUC__
typedef long ssize_t;
typedef int pid_t;
# endif /*!__GNUC__*/
#else
# include <sys/socket.h>
# include <sys/time.h>
#@INSERT_SYS_SELECT_H@
#endif /*!_WIN32*/
@FALLBACK_SOCKLEN_T@
/* This is required for error code compatibility. */
#define _GCRY_ERR_SOURCE_DEFAULT GPG_ERR_SOURCE_GCRYPT
#ifdef __cplusplus
extern "C" {
#if 0 /* (Keep Emacsens' auto-indent happy.) */
}
#endif
#endif
/* The version of this header should match the one of the library. It
should not be used by a program because gcry_check_version() should
return the same version. The purpose of this macro is to let
autoconf (using the AM_PATH_GCRYPT macro) check that this header
matches the installed library. */
#define GCRYPT_VERSION "@VERSION@"
/* The version number of this header. It may be used to handle minor
API incompatibilities. */
#define GCRYPT_VERSION_NUMBER @VERSION_NUMBER@
/* Internal: We can't use the convenience macros for the multi
precision integer functions when building this library. */
#ifdef _GCRYPT_IN_LIBGCRYPT
#ifndef GCRYPT_NO_MPI_MACROS
#define GCRYPT_NO_MPI_MACROS 1
#endif
#endif
/* We want to use gcc attributes when possible. Warning: Don't use
these macros in your programs: As indicated by the leading
underscore they are subject to change without notice. */
#ifdef __GNUC__
#define _GCRY_GCC_VERSION (__GNUC__ * 10000 \
+ __GNUC_MINOR__ * 100 \
+ __GNUC_PATCHLEVEL__)
#if _GCRY_GCC_VERSION >= 30100
#define _GCRY_GCC_ATTR_DEPRECATED __attribute__ ((__deprecated__))
#endif
#if _GCRY_GCC_VERSION >= 29600
#define _GCRY_GCC_ATTR_PURE __attribute__ ((__pure__))
#endif
#if _GCRY_GCC_VERSION >= 30200
#define _GCRY_GCC_ATTR_MALLOC __attribute__ ((__malloc__))
#endif
#define _GCRY_GCC_ATTR_PRINTF(f,a) __attribute__ ((format (printf,f,a)))
#if _GCRY_GCC_VERSION >= 40000
#define _GCRY_GCC_ATTR_SENTINEL(a) __attribute__ ((sentinel(a)))
#endif
#endif /*__GNUC__*/
#ifndef _GCRY_GCC_ATTR_DEPRECATED
#define _GCRY_GCC_ATTR_DEPRECATED
#endif
#ifndef _GCRY_GCC_ATTR_PURE
#define _GCRY_GCC_ATTR_PURE
#endif
#ifndef _GCRY_GCC_ATTR_MALLOC
#define _GCRY_GCC_ATTR_MALLOC
#endif
#ifndef _GCRY_GCC_ATTR_PRINTF
#define _GCRY_GCC_ATTR_PRINTF(f,a)
#endif
#ifndef _GCRY_GCC_ATTR_SENTINEL
#define _GCRY_GCC_ATTR_SENTINEL(a)
#endif
/* Make up an attribute to mark functions and types as deprecated but
allow internal use by Libgcrypt. */
#ifdef _GCRYPT_IN_LIBGCRYPT
#define _GCRY_ATTR_INTERNAL
#else
#define _GCRY_ATTR_INTERNAL _GCRY_GCC_ATTR_DEPRECATED
#endif
/* Wrappers for the libgpg-error library. */
typedef gpg_error_t gcry_error_t;
typedef gpg_err_code_t gcry_err_code_t;
typedef gpg_err_source_t gcry_err_source_t;
static GPG_ERR_INLINE gcry_error_t
gcry_err_make (gcry_err_source_t source, gcry_err_code_t code)
{
return gpg_err_make (source, code);
}
/* The user can define GPG_ERR_SOURCE_DEFAULT before including this
file to specify a default source for gpg_error. */
#ifndef GCRY_ERR_SOURCE_DEFAULT
#define GCRY_ERR_SOURCE_DEFAULT GPG_ERR_SOURCE_USER_1
#endif
static GPG_ERR_INLINE gcry_error_t
gcry_error (gcry_err_code_t code)
{
return gcry_err_make (GCRY_ERR_SOURCE_DEFAULT, code);
}
static GPG_ERR_INLINE gcry_err_code_t
gcry_err_code (gcry_error_t err)
{
return gpg_err_code (err);
}
static GPG_ERR_INLINE gcry_err_source_t
gcry_err_source (gcry_error_t err)
{
return gpg_err_source (err);
}
/* Return a pointer to a string containing a description of the error
code in the error value ERR. */
const char *gcry_strerror (gcry_error_t err);
/* Return a pointer to a string containing a description of the error
source in the error value ERR. */
const char *gcry_strsource (gcry_error_t err);
/* Retrieve the error code for the system error ERR. This returns
GPG_ERR_UNKNOWN_ERRNO if the system error is not mapped (report
this). */
gcry_err_code_t gcry_err_code_from_errno (int err);
/* Retrieve the system error for the error code CODE. This returns 0
if CODE is not a system error code. */
int gcry_err_code_to_errno (gcry_err_code_t code);
/* Return an error value with the error source SOURCE and the system
error ERR. */
gcry_error_t gcry_err_make_from_errno (gcry_err_source_t source, int err);
/* Return an error value with the system error ERR. */
gcry_error_t gcry_error_from_errno (int err);
/* NOTE: Since Libgcrypt 1.6 the thread callbacks are not anymore
used. However we keep it to allow for some source code
compatibility if used in the standard way. */
/* Constants defining the thread model to use. Used with the OPTION
field of the struct gcry_thread_cbs. */
#define GCRY_THREAD_OPTION_DEFAULT 0
#define GCRY_THREAD_OPTION_USER 1
#define GCRY_THREAD_OPTION_PTH 2
#define GCRY_THREAD_OPTION_PTHREAD 3
/* The version number encoded in the OPTION field of the struct
gcry_thread_cbs. */
#define GCRY_THREAD_OPTION_VERSION 1
/* Wrapper for struct ath_ops. */
struct gcry_thread_cbs
{
/* The OPTION field encodes the thread model and the version number
of this structure.
Bits 7 - 0 are used for the thread model
Bits 15 - 8 are used for the version number. */
unsigned int option;
} _GCRY_ATTR_INTERNAL;
#define GCRY_THREAD_OPTION_PTH_IMPL \
static struct gcry_thread_cbs gcry_threads_pth = { \
(GCRY_THREAD_OPTION_PTH | (GCRY_THREAD_OPTION_VERSION << 8))}
#define GCRY_THREAD_OPTION_PTHREAD_IMPL \
static struct gcry_thread_cbs gcry_threads_pthread = { \
(GCRY_THREAD_OPTION_PTHREAD | (GCRY_THREAD_OPTION_VERSION << 8))}
/* A generic context object as used by some functions. */
struct gcry_context;
typedef struct gcry_context *gcry_ctx_t;
/* The data objects used to hold multi precision integers. */
struct gcry_mpi;
typedef struct gcry_mpi *gcry_mpi_t;
struct gcry_mpi_point;
typedef struct gcry_mpi_point *gcry_mpi_point_t;
#ifndef GCRYPT_NO_DEPRECATED
typedef struct gcry_mpi *GCRY_MPI _GCRY_GCC_ATTR_DEPRECATED;
typedef struct gcry_mpi *GcryMPI _GCRY_GCC_ATTR_DEPRECATED;
#endif
/* A structure used for scatter gather hashing. */
typedef struct
{
size_t size; /* The allocated size of the buffer or 0. */
size_t off; /* Offset into the buffer. */
size_t len; /* The used length of the buffer. */
void *data; /* The buffer. */
} gcry_buffer_t;
/* Check that the library fulfills the version requirement. */
const char *gcry_check_version (const char *req_version);
/* Codes for function dispatchers. */
/* Codes used with the gcry_control function. */
enum gcry_ctl_cmds
{
/* Note: 1 .. 2 are not anymore used. */
GCRYCTL_CFB_SYNC = 3,
GCRYCTL_RESET = 4, /* e.g. for MDs */
GCRYCTL_FINALIZE = 5,
GCRYCTL_GET_KEYLEN = 6,
GCRYCTL_GET_BLKLEN = 7,
GCRYCTL_TEST_ALGO = 8,
GCRYCTL_IS_SECURE = 9,
GCRYCTL_GET_ASNOID = 10,
GCRYCTL_ENABLE_ALGO = 11,
GCRYCTL_DISABLE_ALGO = 12,
GCRYCTL_DUMP_RANDOM_STATS = 13,
GCRYCTL_DUMP_SECMEM_STATS = 14,
GCRYCTL_GET_ALGO_NPKEY = 15,
GCRYCTL_GET_ALGO_NSKEY = 16,
GCRYCTL_GET_ALGO_NSIGN = 17,
GCRYCTL_GET_ALGO_NENCR = 18,
GCRYCTL_SET_VERBOSITY = 19,
GCRYCTL_SET_DEBUG_FLAGS = 20,
GCRYCTL_CLEAR_DEBUG_FLAGS = 21,
GCRYCTL_USE_SECURE_RNDPOOL= 22,
GCRYCTL_DUMP_MEMORY_STATS = 23,
GCRYCTL_INIT_SECMEM = 24,
GCRYCTL_TERM_SECMEM = 25,
GCRYCTL_DISABLE_SECMEM_WARN = 27,
GCRYCTL_SUSPEND_SECMEM_WARN = 28,
GCRYCTL_RESUME_SECMEM_WARN = 29,
GCRYCTL_DROP_PRIVS = 30,
GCRYCTL_ENABLE_M_GUARD = 31,
GCRYCTL_START_DUMP = 32,
GCRYCTL_STOP_DUMP = 33,
GCRYCTL_GET_ALGO_USAGE = 34,
GCRYCTL_IS_ALGO_ENABLED = 35,
GCRYCTL_DISABLE_INTERNAL_LOCKING = 36,
GCRYCTL_DISABLE_SECMEM = 37,
GCRYCTL_INITIALIZATION_FINISHED = 38,
GCRYCTL_INITIALIZATION_FINISHED_P = 39,
GCRYCTL_ANY_INITIALIZATION_P = 40,
GCRYCTL_SET_CBC_CTS = 41,
GCRYCTL_SET_CBC_MAC = 42,
/* Note: 43 is not anymore used. */
GCRYCTL_ENABLE_QUICK_RANDOM = 44,
GCRYCTL_SET_RANDOM_SEED_FILE = 45,
GCRYCTL_UPDATE_RANDOM_SEED_FILE = 46,
GCRYCTL_SET_THREAD_CBS = 47,
GCRYCTL_FAST_POLL = 48,
GCRYCTL_SET_RANDOM_DAEMON_SOCKET = 49,
GCRYCTL_USE_RANDOM_DAEMON = 50,
GCRYCTL_FAKED_RANDOM_P = 51,
GCRYCTL_SET_RNDEGD_SOCKET = 52,
GCRYCTL_PRINT_CONFIG = 53,
GCRYCTL_OPERATIONAL_P = 54,
GCRYCTL_FIPS_MODE_P = 55,
GCRYCTL_FORCE_FIPS_MODE = 56,
GCRYCTL_SELFTEST = 57,
/* Note: 58 .. 62 are used internally. */
GCRYCTL_DISABLE_HWF = 63,
GCRYCTL_SET_ENFORCED_FIPS_FLAG = 64,
GCRYCTL_SET_PREFERRED_RNG_TYPE = 65,
GCRYCTL_GET_CURRENT_RNG_TYPE = 66,
GCRYCTL_DISABLE_LOCKED_SECMEM = 67,
GCRYCTL_DISABLE_PRIV_DROP = 68,
GCRYCTL_SET_CCM_LENGTHS = 69,
GCRYCTL_CLOSE_RANDOM_DEVICE = 70,
GCRYCTL_INACTIVATE_FIPS_FLAG = 71,
GCRYCTL_REACTIVATE_FIPS_FLAG = 72,
GCRYCTL_SET_SBOX = 73,
GCRYCTL_DRBG_REINIT = 74,
GCRYCTL_SET_TAGLEN = 75,
GCRYCTL_GET_TAGLEN = 76,
- GCRYCTL_REINIT_SYSCALL_CLAMP = 77
+ GCRYCTL_REINIT_SYSCALL_CLAMP = 77,
+ GCRYCTL_AUTO_EXPAND_SECMEM = 78
};
/* Perform various operations defined by CMD. */
gcry_error_t gcry_control (enum gcry_ctl_cmds CMD, ...);
/* S-expression management. */
/* The object to represent an S-expression as used with the public key
functions. */
struct gcry_sexp;
typedef struct gcry_sexp *gcry_sexp_t;
#ifndef GCRYPT_NO_DEPRECATED
typedef struct gcry_sexp *GCRY_SEXP _GCRY_GCC_ATTR_DEPRECATED;
typedef struct gcry_sexp *GcrySexp _GCRY_GCC_ATTR_DEPRECATED;
#endif
/* The possible values for the S-expression format. */
enum gcry_sexp_format
{
GCRYSEXP_FMT_DEFAULT = 0,
GCRYSEXP_FMT_CANON = 1,
GCRYSEXP_FMT_BASE64 = 2,
GCRYSEXP_FMT_ADVANCED = 3
};
/* Create an new S-expression object from BUFFER of size LENGTH and
return it in RETSEXP. With AUTODETECT set to 0 the data in BUFFER
is expected to be in canonized format. */
gcry_error_t gcry_sexp_new (gcry_sexp_t *retsexp,
const void *buffer, size_t length,
int autodetect);
/* Same as gcry_sexp_new but allows to pass a FREEFNC which has the
effect to transfer ownership of BUFFER to the created object. */
gcry_error_t gcry_sexp_create (gcry_sexp_t *retsexp,
void *buffer, size_t length,
int autodetect, void (*freefnc) (void *));
/* Scan BUFFER and return a new S-expression object in RETSEXP. This
function expects a printf like string in BUFFER. */
gcry_error_t gcry_sexp_sscan (gcry_sexp_t *retsexp, size_t *erroff,
const char *buffer, size_t length);
/* Same as gcry_sexp_sscan but expects a string in FORMAT and can thus
only be used for certain encodings. */
gcry_error_t gcry_sexp_build (gcry_sexp_t *retsexp, size_t *erroff,
const char *format, ...);
/* Like gcry_sexp_build, but uses an array instead of variable
function arguments. */
gcry_error_t gcry_sexp_build_array (gcry_sexp_t *retsexp, size_t *erroff,
const char *format, void **arg_list);
/* Release the S-expression object SEXP */
void gcry_sexp_release (gcry_sexp_t sexp);
/* Calculate the length of an canonized S-expression in BUFFER and
check for a valid encoding. */
size_t gcry_sexp_canon_len (const unsigned char *buffer, size_t length,
size_t *erroff, gcry_error_t *errcode);
/* Copies the S-expression object SEXP into BUFFER using the format
specified in MODE. */
size_t gcry_sexp_sprint (gcry_sexp_t sexp, int mode, void *buffer,
size_t maxlength);
/* Dumps the S-expression object A in a format suitable for debugging
to Libgcrypt's logging stream. */
void gcry_sexp_dump (const gcry_sexp_t a);
gcry_sexp_t gcry_sexp_cons (const gcry_sexp_t a, const gcry_sexp_t b);
gcry_sexp_t gcry_sexp_alist (const gcry_sexp_t *array);
gcry_sexp_t gcry_sexp_vlist (const gcry_sexp_t a, ...);
gcry_sexp_t gcry_sexp_append (const gcry_sexp_t a, const gcry_sexp_t n);
gcry_sexp_t gcry_sexp_prepend (const gcry_sexp_t a, const gcry_sexp_t n);
/* Scan the S-expression for a sublist with a type (the car of the
list) matching the string TOKEN. If TOKLEN is not 0, the token is
assumed to be raw memory of this length. The function returns a
newly allocated S-expression consisting of the found sublist or
`NULL' when not found. */
gcry_sexp_t gcry_sexp_find_token (gcry_sexp_t list,
const char *tok, size_t toklen);
/* Return the length of the LIST. For a valid S-expression this
should be at least 1. */
int gcry_sexp_length (const gcry_sexp_t list);
/* Create and return a new S-expression from the element with index
NUMBER in LIST. Note that the first element has the index 0. If
there is no such element, `NULL' is returned. */
gcry_sexp_t gcry_sexp_nth (const gcry_sexp_t list, int number);
/* Create and return a new S-expression from the first element in
LIST; this called the "type" and should always exist and be a
string. `NULL' is returned in case of a problem. */
gcry_sexp_t gcry_sexp_car (const gcry_sexp_t list);
/* Create and return a new list form all elements except for the first
one. Note, that this function may return an invalid S-expression
because it is not guaranteed, that the type exists and is a string.
However, for parsing a complex S-expression it might be useful for
intermediate lists. Returns `NULL' on error. */
gcry_sexp_t gcry_sexp_cdr (const gcry_sexp_t list);
gcry_sexp_t gcry_sexp_cadr (const gcry_sexp_t list);
/* This function is used to get data from a LIST. A pointer to the
actual data with index NUMBER is returned and the length of this
data will be stored to DATALEN. If there is no data at the given
index or the index represents another list, `NULL' is returned.
*Note:* The returned pointer is valid as long as LIST is not
modified or released. */
const char *gcry_sexp_nth_data (const gcry_sexp_t list, int number,
size_t *datalen);
/* This function is used to get data from a LIST. A malloced buffer to the
data with index NUMBER is returned and the length of this
data will be stored to RLENGTH. If there is no data at the given
index or the index represents another list, `NULL' is returned. */
void *gcry_sexp_nth_buffer (const gcry_sexp_t list, int number,
size_t *rlength);
/* This function is used to get and convert data from a LIST. The
data is assumed to be a Nul terminated string. The caller must
release the returned value using `gcry_free'. If there is no data
at the given index, the index represents a list or the value can't
be converted to a string, `NULL' is returned. */
char *gcry_sexp_nth_string (gcry_sexp_t list, int number);
/* This function is used to get and convert data from a LIST. This
data is assumed to be an MPI stored in the format described by
MPIFMT and returned as a standard Libgcrypt MPI. The caller must
release this returned value using `gcry_mpi_release'. If there is
no data at the given index, the index represents a list or the
value can't be converted to an MPI, `NULL' is returned. */
gcry_mpi_t gcry_sexp_nth_mpi (gcry_sexp_t list, int number, int mpifmt);
/* Extract MPIs from an s-expression using a list of parameters. The
* names of these parameters are given by the string LIST. Some
* special characters may be given to control the conversion:
*
* + :: Switch to unsigned integer format (default).
* - :: Switch to standard signed format.
* / :: Switch to opaque format.
* & :: Switch to buffer descriptor mode - see below.
* ? :: The previous parameter is optional.
*
* In general parameter names are single letters. To use a string for
* a parameter name, enclose the name in single quotes.
*
* Unless in gcry_buffer_t mode for each parameter name a pointer to
* an MPI variable is expected that must be set to NULL prior to
* invoking this function, and finally a NULL is expected. Example:
*
* _gcry_sexp_extract_param (key, NULL, "n/x+ed",
* &mpi_n, &mpi_x, &mpi_e, NULL)
*
* This stores the parameter "N" from KEY as an unsigned MPI into
* MPI_N, the parameter "X" as an opaque MPI into MPI_X, and the
* parameter "E" again as an unsigned MPI into MPI_E.
*
* If in buffer descriptor mode a pointer to gcry_buffer_t descriptor
* is expected instead of a pointer to an MPI. The caller may use two
* different operation modes: If the DATA field of the provided buffer
* descriptor is NULL, the function allocates a new buffer and stores
* it at DATA; the other fields are set accordingly with OFF being 0.
* If DATA is not NULL, the function assumes that DATA, SIZE, and OFF
* describe a buffer where to but the data; on return the LEN field
* receives the number of bytes copied to that buffer; if the buffer
* is too small, the function immediately returns with an error code
* (and LEN set to 0).
*
* PATH is an optional string used to locate a token. The exclamation
* mark separated tokens are used to via gcry_sexp_find_token to find
* a start point inside SEXP.
*
* The function returns 0 on success. On error an error code is
* returned, all passed MPIs that might have been allocated up to this
* point are deallocated and set to NULL, and all passed buffers are
* either truncated if the caller supplied the buffer, or deallocated
* if the function allocated the buffer.
*/
gpg_error_t gcry_sexp_extract_param (gcry_sexp_t sexp,
const char *path,
const char *list,
...) _GCRY_GCC_ATTR_SENTINEL(0);
/*******************************************
* *
* Multi Precision Integer Functions *
* *
*******************************************/
/* Different formats of external big integer representation. */
enum gcry_mpi_format
{
GCRYMPI_FMT_NONE= 0,
GCRYMPI_FMT_STD = 1, /* Twos complement stored without length. */
GCRYMPI_FMT_PGP = 2, /* As used by OpenPGP (unsigned only). */
GCRYMPI_FMT_SSH = 3, /* As used by SSH (like STD but with length). */
GCRYMPI_FMT_HEX = 4, /* Hex format. */
GCRYMPI_FMT_USG = 5, /* Like STD but unsigned. */
GCRYMPI_FMT_OPAQUE = 8 /* Opaque format (some functions only). */
};
/* Flags used for creating big integers. */
enum gcry_mpi_flag
{
GCRYMPI_FLAG_SECURE = 1, /* Allocate the number in "secure" memory. */
GCRYMPI_FLAG_OPAQUE = 2, /* The number is not a real one but just
a way to store some bytes. This is
useful for encrypted big integers. */
GCRYMPI_FLAG_IMMUTABLE = 4, /* Mark the MPI as immutable. */
GCRYMPI_FLAG_CONST = 8, /* Mark the MPI as a constant. */
GCRYMPI_FLAG_USER1 = 0x0100,/* User flag 1. */
GCRYMPI_FLAG_USER2 = 0x0200,/* User flag 2. */
GCRYMPI_FLAG_USER3 = 0x0400,/* User flag 3. */
GCRYMPI_FLAG_USER4 = 0x0800 /* User flag 4. */
};
/* Macros to return pre-defined MPI constants. */
#define GCRYMPI_CONST_ONE (_gcry_mpi_get_const (1))
#define GCRYMPI_CONST_TWO (_gcry_mpi_get_const (2))
#define GCRYMPI_CONST_THREE (_gcry_mpi_get_const (3))
#define GCRYMPI_CONST_FOUR (_gcry_mpi_get_const (4))
#define GCRYMPI_CONST_EIGHT (_gcry_mpi_get_const (8))
/* Allocate a new big integer object, initialize it with 0 and
initially allocate memory for a number of at least NBITS. */
gcry_mpi_t gcry_mpi_new (unsigned int nbits);
/* Same as gcry_mpi_new() but allocate in "secure" memory. */
gcry_mpi_t gcry_mpi_snew (unsigned int nbits);
/* Release the number A and free all associated resources. */
void gcry_mpi_release (gcry_mpi_t a);
/* Create a new number with the same value as A. */
gcry_mpi_t gcry_mpi_copy (const gcry_mpi_t a);
/* Store the big integer value U in W and release U. */
void gcry_mpi_snatch (gcry_mpi_t w, gcry_mpi_t u);
/* Store the big integer value U in W. */
gcry_mpi_t gcry_mpi_set (gcry_mpi_t w, const gcry_mpi_t u);
/* Store the unsigned integer value U in W. */
gcry_mpi_t gcry_mpi_set_ui (gcry_mpi_t w, unsigned long u);
/* Store U as an unsigned int at W or return GPG_ERR_ERANGE. */
gpg_error_t gcry_mpi_get_ui (unsigned int *w, gcry_mpi_t u);
/* Swap the values of A and B. */
void gcry_mpi_swap (gcry_mpi_t a, gcry_mpi_t b);
/* Return 1 if A is negative; 0 if zero or positive. */
int gcry_mpi_is_neg (gcry_mpi_t a);
/* W = - U */
void gcry_mpi_neg (gcry_mpi_t w, gcry_mpi_t u);
/* W = [W] */
void gcry_mpi_abs (gcry_mpi_t w);
/* Compare the big integer number U and V returning 0 for equality, a
positive value for U > V and a negative for U < V. */
int gcry_mpi_cmp (const gcry_mpi_t u, const gcry_mpi_t v);
/* Compare the big integer number U with the unsigned integer V
returning 0 for equality, a positive value for U > V and a negative
for U < V. */
int gcry_mpi_cmp_ui (const gcry_mpi_t u, unsigned long v);
/* Convert the external representation of an integer stored in BUFFER
with a length of BUFLEN into a newly create MPI returned in
RET_MPI. If NSCANNED is not NULL, it will receive the number of
bytes actually scanned after a successful operation. */
gcry_error_t gcry_mpi_scan (gcry_mpi_t *ret_mpi, enum gcry_mpi_format format,
const void *buffer, size_t buflen,
size_t *nscanned);
/* Convert the big integer A into the external representation
described by FORMAT and store it in the provided BUFFER which has
been allocated by the user with a size of BUFLEN bytes. NWRITTEN
receives the actual length of the external representation unless it
has been passed as NULL. */
gcry_error_t gcry_mpi_print (enum gcry_mpi_format format,
unsigned char *buffer, size_t buflen,
size_t *nwritten,
const gcry_mpi_t a);
/* Convert the big integer A into the external representation described
by FORMAT and store it in a newly allocated buffer which address
will be put into BUFFER. NWRITTEN receives the actual lengths of the
external representation. */
gcry_error_t gcry_mpi_aprint (enum gcry_mpi_format format,
unsigned char **buffer, size_t *nwritten,
const gcry_mpi_t a);
/* Dump the value of A in a format suitable for debugging to
Libgcrypt's logging stream. Note that one leading space but no
trailing space or linefeed will be printed. It is okay to pass
NULL for A. */
void gcry_mpi_dump (const gcry_mpi_t a);
/* W = U + V. */
void gcry_mpi_add (gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v);
/* W = U + V. V is an unsigned integer. */
void gcry_mpi_add_ui (gcry_mpi_t w, gcry_mpi_t u, unsigned long v);
/* W = U + V mod M. */
void gcry_mpi_addm (gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v, gcry_mpi_t m);
/* W = U - V. */
void gcry_mpi_sub (gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v);
/* W = U - V. V is an unsigned integer. */
void gcry_mpi_sub_ui (gcry_mpi_t w, gcry_mpi_t u, unsigned long v );
/* W = U - V mod M */
void gcry_mpi_subm (gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v, gcry_mpi_t m);
/* W = U * V. */
void gcry_mpi_mul (gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v);
/* W = U * V. V is an unsigned integer. */
void gcry_mpi_mul_ui (gcry_mpi_t w, gcry_mpi_t u, unsigned long v );
/* W = U * V mod M. */
void gcry_mpi_mulm (gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v, gcry_mpi_t m);
/* W = U * (2 ^ CNT). */
void gcry_mpi_mul_2exp (gcry_mpi_t w, gcry_mpi_t u, unsigned long cnt);
/* Q = DIVIDEND / DIVISOR, R = DIVIDEND % DIVISOR,
Q or R may be passed as NULL. ROUND should be negative or 0. */
void gcry_mpi_div (gcry_mpi_t q, gcry_mpi_t r,
gcry_mpi_t dividend, gcry_mpi_t divisor, int round);
/* R = DIVIDEND % DIVISOR */
void gcry_mpi_mod (gcry_mpi_t r, gcry_mpi_t dividend, gcry_mpi_t divisor);
/* W = B ^ E mod M. */
void gcry_mpi_powm (gcry_mpi_t w,
const gcry_mpi_t b, const gcry_mpi_t e,
const gcry_mpi_t m);
/* Set G to the greatest common divisor of A and B.
Return true if the G is 1. */
int gcry_mpi_gcd (gcry_mpi_t g, gcry_mpi_t a, gcry_mpi_t b);
/* Set X to the multiplicative inverse of A mod M.
Return true if the value exists. */
int gcry_mpi_invm (gcry_mpi_t x, gcry_mpi_t a, gcry_mpi_t m);
/* Create a new point object. NBITS is usually 0. */
gcry_mpi_point_t gcry_mpi_point_new (unsigned int nbits);
/* Release the object POINT. POINT may be NULL. */
void gcry_mpi_point_release (gcry_mpi_point_t point);
/* Return a copy of POINT. */
gcry_mpi_point_t gcry_mpi_point_copy (gcry_mpi_point_t point);
/* Store the projective coordinates from POINT into X, Y, and Z. */
void gcry_mpi_point_get (gcry_mpi_t x, gcry_mpi_t y, gcry_mpi_t z,
gcry_mpi_point_t point);
/* Store the projective coordinates from POINT into X, Y, and Z and
release POINT. */
void gcry_mpi_point_snatch_get (gcry_mpi_t x, gcry_mpi_t y, gcry_mpi_t z,
gcry_mpi_point_t point);
/* Store the projective coordinates X, Y, and Z into POINT. */
gcry_mpi_point_t gcry_mpi_point_set (gcry_mpi_point_t point,
gcry_mpi_t x, gcry_mpi_t y, gcry_mpi_t z);
/* Store the projective coordinates X, Y, and Z into POINT and release
X, Y, and Z. */
gcry_mpi_point_t gcry_mpi_point_snatch_set (gcry_mpi_point_t point,
gcry_mpi_t x, gcry_mpi_t y,
gcry_mpi_t z);
/* Allocate a new context for elliptic curve operations based on the
parameters given by KEYPARAM or using CURVENAME. */
gpg_error_t gcry_mpi_ec_new (gcry_ctx_t *r_ctx,
gcry_sexp_t keyparam, const char *curvename);
/* Get a named MPI from an elliptic curve context. */
gcry_mpi_t gcry_mpi_ec_get_mpi (const char *name, gcry_ctx_t ctx, int copy);
/* Get a named point from an elliptic curve context. */
gcry_mpi_point_t gcry_mpi_ec_get_point (const char *name,
gcry_ctx_t ctx, int copy);
/* Store a named MPI into an elliptic curve context. */
gpg_error_t gcry_mpi_ec_set_mpi (const char *name, gcry_mpi_t newvalue,
gcry_ctx_t ctx);
/* Store a named point into an elliptic curve context. */
gpg_error_t gcry_mpi_ec_set_point (const char *name, gcry_mpi_point_t newvalue,
gcry_ctx_t ctx);
/* Decode and store VALUE into RESULT. */
gpg_error_t gcry_mpi_ec_decode_point (gcry_mpi_point_t result,
gcry_mpi_t value, gcry_ctx_t ctx);
/* Store the affine coordinates of POINT into X and Y. */
int gcry_mpi_ec_get_affine (gcry_mpi_t x, gcry_mpi_t y, gcry_mpi_point_t point,
gcry_ctx_t ctx);
/* W = 2 * U. */
void gcry_mpi_ec_dup (gcry_mpi_point_t w, gcry_mpi_point_t u, gcry_ctx_t ctx);
/* W = U + V. */
void gcry_mpi_ec_add (gcry_mpi_point_t w,
gcry_mpi_point_t u, gcry_mpi_point_t v, gcry_ctx_t ctx);
/* W = U - V. */
void gcry_mpi_ec_sub (gcry_mpi_point_t w,
gcry_mpi_point_t u, gcry_mpi_point_t v, gcry_ctx_t ctx);
/* W = N * U. */
void gcry_mpi_ec_mul (gcry_mpi_point_t w, gcry_mpi_t n, gcry_mpi_point_t u,
gcry_ctx_t ctx);
/* Return true if POINT is on the curve described by CTX. */
int gcry_mpi_ec_curve_point (gcry_mpi_point_t w, gcry_ctx_t ctx);
/* Return the number of bits required to represent A. */
unsigned int gcry_mpi_get_nbits (gcry_mpi_t a);
/* Return true when bit number N (counting from 0) is set in A. */
int gcry_mpi_test_bit (gcry_mpi_t a, unsigned int n);
/* Set bit number N in A. */
void gcry_mpi_set_bit (gcry_mpi_t a, unsigned int n);
/* Clear bit number N in A. */
void gcry_mpi_clear_bit (gcry_mpi_t a, unsigned int n);
/* Set bit number N in A and clear all bits greater than N. */
void gcry_mpi_set_highbit (gcry_mpi_t a, unsigned int n);
/* Clear bit number N in A and all bits greater than N. */
void gcry_mpi_clear_highbit (gcry_mpi_t a, unsigned int n);
/* Shift the value of A by N bits to the right and store the result in X. */
void gcry_mpi_rshift (gcry_mpi_t x, gcry_mpi_t a, unsigned int n);
/* Shift the value of A by N bits to the left and store the result in X. */
void gcry_mpi_lshift (gcry_mpi_t x, gcry_mpi_t a, unsigned int n);
/* Store NBITS of the value P points to in A and mark A as an opaque
value. On success A received the the ownership of the value P.
WARNING: Never use an opaque MPI for anything thing else than
gcry_mpi_release, gcry_mpi_get_opaque. */
gcry_mpi_t gcry_mpi_set_opaque (gcry_mpi_t a, void *p, unsigned int nbits);
/* Store NBITS of the value P points to in A and mark A as an opaque
value. The function takes a copy of the provided value P.
WARNING: Never use an opaque MPI for anything thing else than
gcry_mpi_release, gcry_mpi_get_opaque. */
gcry_mpi_t gcry_mpi_set_opaque_copy (gcry_mpi_t a,
const void *p, unsigned int nbits);
/* Return a pointer to an opaque value stored in A and return its size
in NBITS. Note that the returned pointer is still owned by A and
that the function should never be used for an non-opaque MPI. */
void *gcry_mpi_get_opaque (gcry_mpi_t a, unsigned int *nbits);
/* Set the FLAG for the big integer A. Currently only the flag
GCRYMPI_FLAG_SECURE is allowed to convert A into an big intger
stored in "secure" memory. */
void gcry_mpi_set_flag (gcry_mpi_t a, enum gcry_mpi_flag flag);
/* Clear FLAG for the big integer A. Note that this function is
currently useless as no flags are allowed. */
void gcry_mpi_clear_flag (gcry_mpi_t a, enum gcry_mpi_flag flag);
/* Return true if the FLAG is set for A. */
int gcry_mpi_get_flag (gcry_mpi_t a, enum gcry_mpi_flag flag);
/* Private function - do not use. */
gcry_mpi_t _gcry_mpi_get_const (int no);
/* Unless the GCRYPT_NO_MPI_MACROS is used, provide a couple of
convenience macros for the big integer functions. */
#ifndef GCRYPT_NO_MPI_MACROS
#define mpi_new(n) gcry_mpi_new( (n) )
#define mpi_secure_new( n ) gcry_mpi_snew( (n) )
#define mpi_release(a) \
do \
{ \
gcry_mpi_release ((a)); \
(a) = NULL; \
} \
while (0)
#define mpi_copy( a ) gcry_mpi_copy( (a) )
#define mpi_snatch( w, u) gcry_mpi_snatch( (w), (u) )
#define mpi_set( w, u) gcry_mpi_set( (w), (u) )
#define mpi_set_ui( w, u) gcry_mpi_set_ui( (w), (u) )
#define mpi_get_ui( w, u) gcry_mpi_get_ui( (w), (u) )
#define mpi_abs( w ) gcry_mpi_abs( (w) )
#define mpi_neg( w, u) gcry_mpi_neg( (w), (u) )
#define mpi_cmp( u, v ) gcry_mpi_cmp( (u), (v) )
#define mpi_cmp_ui( u, v ) gcry_mpi_cmp_ui( (u), (v) )
#define mpi_is_neg( a ) gcry_mpi_is_neg ((a))
#define mpi_add_ui(w,u,v) gcry_mpi_add_ui((w),(u),(v))
#define mpi_add(w,u,v) gcry_mpi_add ((w),(u),(v))
#define mpi_addm(w,u,v,m) gcry_mpi_addm ((w),(u),(v),(m))
#define mpi_sub_ui(w,u,v) gcry_mpi_sub_ui ((w),(u),(v))
#define mpi_sub(w,u,v) gcry_mpi_sub ((w),(u),(v))
#define mpi_subm(w,u,v,m) gcry_mpi_subm ((w),(u),(v),(m))
#define mpi_mul_ui(w,u,v) gcry_mpi_mul_ui ((w),(u),(v))
#define mpi_mul_2exp(w,u,v) gcry_mpi_mul_2exp ((w),(u),(v))
#define mpi_mul(w,u,v) gcry_mpi_mul ((w),(u),(v))
#define mpi_mulm(w,u,v,m) gcry_mpi_mulm ((w),(u),(v),(m))
#define mpi_powm(w,b,e,m) gcry_mpi_powm ( (w), (b), (e), (m) )
#define mpi_tdiv(q,r,a,m) gcry_mpi_div ( (q), (r), (a), (m), 0)
#define mpi_fdiv(q,r,a,m) gcry_mpi_div ( (q), (r), (a), (m), -1)
#define mpi_mod(r,a,m) gcry_mpi_mod ((r), (a), (m))
#define mpi_gcd(g,a,b) gcry_mpi_gcd ( (g), (a), (b) )
#define mpi_invm(g,a,b) gcry_mpi_invm ( (g), (a), (b) )
#define mpi_point_new(n) gcry_mpi_point_new((n))
#define mpi_point_release(p) \
do \
{ \
gcry_mpi_point_release ((p)); \
(p) = NULL; \
} \
while (0)
#define mpi_point_copy(p) gcry_mpi_point_copy((p))
#define mpi_point_get(x,y,z,p) gcry_mpi_point_get((x),(y),(z),(p))
#define mpi_point_snatch_get(x,y,z,p) gcry_mpi_point_snatch_get((x),(y),(z),(p))
#define mpi_point_set(p,x,y,z) gcry_mpi_point_set((p),(x),(y),(z))
#define mpi_point_snatch_set(p,x,y,z) gcry_mpi_point_snatch_set((p),(x),(y),(z))
#define mpi_get_nbits(a) gcry_mpi_get_nbits ((a))
#define mpi_test_bit(a,b) gcry_mpi_test_bit ((a),(b))
#define mpi_set_bit(a,b) gcry_mpi_set_bit ((a),(b))
#define mpi_set_highbit(a,b) gcry_mpi_set_highbit ((a),(b))
#define mpi_clear_bit(a,b) gcry_mpi_clear_bit ((a),(b))
#define mpi_clear_highbit(a,b) gcry_mpi_clear_highbit ((a),(b))
#define mpi_rshift(a,b,c) gcry_mpi_rshift ((a),(b),(c))
#define mpi_lshift(a,b,c) gcry_mpi_lshift ((a),(b),(c))
#define mpi_set_opaque(a,b,c) gcry_mpi_set_opaque( (a), (b), (c) )
#define mpi_get_opaque(a,b) gcry_mpi_get_opaque( (a), (b) )
#endif /* GCRYPT_NO_MPI_MACROS */
/************************************
* *
* Symmetric Cipher Functions *
* *
************************************/
/* The data object used to hold a handle to an encryption object. */
struct gcry_cipher_handle;
typedef struct gcry_cipher_handle *gcry_cipher_hd_t;
#ifndef GCRYPT_NO_DEPRECATED
typedef struct gcry_cipher_handle *GCRY_CIPHER_HD _GCRY_GCC_ATTR_DEPRECATED;
typedef struct gcry_cipher_handle *GcryCipherHd _GCRY_GCC_ATTR_DEPRECATED;
#endif
/* All symmetric encryption algorithms are identified by their IDs.
More IDs may be registered at runtime. */
enum gcry_cipher_algos
{
GCRY_CIPHER_NONE = 0,
GCRY_CIPHER_IDEA = 1,
GCRY_CIPHER_3DES = 2,
GCRY_CIPHER_CAST5 = 3,
GCRY_CIPHER_BLOWFISH = 4,
GCRY_CIPHER_SAFER_SK128 = 5,
GCRY_CIPHER_DES_SK = 6,
GCRY_CIPHER_AES = 7,
GCRY_CIPHER_AES192 = 8,
GCRY_CIPHER_AES256 = 9,
GCRY_CIPHER_TWOFISH = 10,
/* Other cipher numbers are above 300 for OpenPGP reasons. */
GCRY_CIPHER_ARCFOUR = 301, /* Fully compatible with RSA's RC4 (tm). */
GCRY_CIPHER_DES = 302, /* Yes, this is single key 56 bit DES. */
GCRY_CIPHER_TWOFISH128 = 303,
GCRY_CIPHER_SERPENT128 = 304,
GCRY_CIPHER_SERPENT192 = 305,
GCRY_CIPHER_SERPENT256 = 306,
GCRY_CIPHER_RFC2268_40 = 307, /* Ron's Cipher 2 (40 bit). */
GCRY_CIPHER_RFC2268_128 = 308, /* Ron's Cipher 2 (128 bit). */
GCRY_CIPHER_SEED = 309, /* 128 bit cipher described in RFC4269. */
GCRY_CIPHER_CAMELLIA128 = 310,
GCRY_CIPHER_CAMELLIA192 = 311,
GCRY_CIPHER_CAMELLIA256 = 312,
GCRY_CIPHER_SALSA20 = 313,
GCRY_CIPHER_SALSA20R12 = 314,
GCRY_CIPHER_GOST28147 = 315,
GCRY_CIPHER_CHACHA20 = 316
};
/* The Rijndael algorithm is basically AES, so provide some macros. */
#define GCRY_CIPHER_AES128 GCRY_CIPHER_AES
#define GCRY_CIPHER_RIJNDAEL GCRY_CIPHER_AES
#define GCRY_CIPHER_RIJNDAEL128 GCRY_CIPHER_AES128
#define GCRY_CIPHER_RIJNDAEL192 GCRY_CIPHER_AES192
#define GCRY_CIPHER_RIJNDAEL256 GCRY_CIPHER_AES256
/* The supported encryption modes. Note that not all of them are
supported for each algorithm. */
enum gcry_cipher_modes
{
GCRY_CIPHER_MODE_NONE = 0, /* Not yet specified. */
GCRY_CIPHER_MODE_ECB = 1, /* Electronic codebook. */
GCRY_CIPHER_MODE_CFB = 2, /* Cipher feedback. */
GCRY_CIPHER_MODE_CBC = 3, /* Cipher block chaining. */
GCRY_CIPHER_MODE_STREAM = 4, /* Used with stream ciphers. */
GCRY_CIPHER_MODE_OFB = 5, /* Outer feedback. */
GCRY_CIPHER_MODE_CTR = 6, /* Counter. */
GCRY_CIPHER_MODE_AESWRAP = 7, /* AES-WRAP algorithm. */
GCRY_CIPHER_MODE_CCM = 8, /* Counter with CBC-MAC. */
GCRY_CIPHER_MODE_GCM = 9, /* Galois Counter Mode. */
GCRY_CIPHER_MODE_POLY1305 = 10, /* Poly1305 based AEAD mode. */
GCRY_CIPHER_MODE_OCB = 11, /* OCB3 mode. */
GCRY_CIPHER_MODE_CFB8 = 12, /* Cipher feedback (8 bit mode). */
GCRY_CIPHER_MODE_XTS = 13 /* XTS mode. */
};
/* Flags used with the open function. */
enum gcry_cipher_flags
{
GCRY_CIPHER_SECURE = 1, /* Allocate in secure memory. */
GCRY_CIPHER_ENABLE_SYNC = 2, /* Enable CFB sync mode. */
GCRY_CIPHER_CBC_CTS = 4, /* Enable CBC cipher text stealing (CTS). */
GCRY_CIPHER_CBC_MAC = 8 /* Enable CBC message auth. code (MAC). */
};
/* GCM works only with blocks of 128 bits */
#define GCRY_GCM_BLOCK_LEN (128 / 8)
/* CCM works only with blocks of 128 bits. */
#define GCRY_CCM_BLOCK_LEN (128 / 8)
/* OCB works only with blocks of 128 bits. */
#define GCRY_OCB_BLOCK_LEN (128 / 8)
/* XTS works only with blocks of 128 bits. */
#define GCRY_XTS_BLOCK_LEN (128 / 8)
/* Create a handle for algorithm ALGO to be used in MODE. FLAGS may
be given as an bitwise OR of the gcry_cipher_flags values. */
gcry_error_t gcry_cipher_open (gcry_cipher_hd_t *handle,
int algo, int mode, unsigned int flags);
/* Close the cipher handle H and release all resource. */
void gcry_cipher_close (gcry_cipher_hd_t h);
/* Perform various operations on the cipher object H. */
gcry_error_t gcry_cipher_ctl (gcry_cipher_hd_t h, int cmd, void *buffer,
size_t buflen);
/* Retrieve various information about the cipher object H. */
gcry_error_t gcry_cipher_info (gcry_cipher_hd_t h, int what, void *buffer,
size_t *nbytes);
/* Retrieve various information about the cipher algorithm ALGO. */
gcry_error_t gcry_cipher_algo_info (int algo, int what, void *buffer,
size_t *nbytes);
/* Map the cipher algorithm whose ID is contained in ALGORITHM to a
string representation of the algorithm name. For unknown algorithm
IDs this function returns "?". */
const char *gcry_cipher_algo_name (int algorithm) _GCRY_GCC_ATTR_PURE;
/* Map the algorithm name NAME to an cipher algorithm ID. Return 0 if
the algorithm name is not known. */
int gcry_cipher_map_name (const char *name) _GCRY_GCC_ATTR_PURE;
/* Given an ASN.1 object identifier in standard IETF dotted decimal
format in STRING, return the encryption mode associated with that
OID or 0 if not known or applicable. */
int gcry_cipher_mode_from_oid (const char *string) _GCRY_GCC_ATTR_PURE;
/* Encrypt the plaintext of size INLEN in IN using the cipher handle H
into the buffer OUT which has an allocated length of OUTSIZE. For
most algorithms it is possible to pass NULL for in and 0 for INLEN
and do a in-place decryption of the data provided in OUT. */
gcry_error_t gcry_cipher_encrypt (gcry_cipher_hd_t h,
void *out, size_t outsize,
const void *in, size_t inlen);
/* The counterpart to gcry_cipher_encrypt. */
gcry_error_t gcry_cipher_decrypt (gcry_cipher_hd_t h,
void *out, size_t outsize,
const void *in, size_t inlen);
/* Set KEY of length KEYLEN bytes for the cipher handle HD. */
gcry_error_t gcry_cipher_setkey (gcry_cipher_hd_t hd,
const void *key, size_t keylen);
/* Set initialization vector IV of length IVLEN for the cipher handle HD. */
gcry_error_t gcry_cipher_setiv (gcry_cipher_hd_t hd,
const void *iv, size_t ivlen);
/* Provide additional authentication data for AEAD modes/ciphers. */
gcry_error_t gcry_cipher_authenticate (gcry_cipher_hd_t hd, const void *abuf,
size_t abuflen);
/* Get authentication tag for AEAD modes/ciphers. */
gcry_error_t gcry_cipher_gettag (gcry_cipher_hd_t hd, void *outtag,
size_t taglen);
/* Check authentication tag for AEAD modes/ciphers. */
gcry_error_t gcry_cipher_checktag (gcry_cipher_hd_t hd, const void *intag,
size_t taglen);
/* Reset the handle to the state after open. */
#define gcry_cipher_reset(h) gcry_cipher_ctl ((h), GCRYCTL_RESET, NULL, 0)
/* Perform the OpenPGP sync operation if this is enabled for the
cipher handle H. */
#define gcry_cipher_sync(h) gcry_cipher_ctl( (h), GCRYCTL_CFB_SYNC, NULL, 0)
/* Enable or disable CTS in future calls to gcry_encrypt(). CBC mode only. */
#define gcry_cipher_cts(h,on) gcry_cipher_ctl( (h), GCRYCTL_SET_CBC_CTS, \
NULL, on )
#define gcry_cipher_set_sbox(h,oid) gcry_cipher_ctl( (h), GCRYCTL_SET_SBOX, \
(void *) oid, 0);
/* Indicate to the encrypt and decrypt functions that the next call
provides the final data. Only used with some modes. */
#define gcry_cipher_final(a) \
gcry_cipher_ctl ((a), GCRYCTL_FINALIZE, NULL, 0)
/* Set counter for CTR mode. (CTR,CTRLEN) must denote a buffer of
block size length, or (NULL,0) to set the CTR to the all-zero block. */
gpg_error_t gcry_cipher_setctr (gcry_cipher_hd_t hd,
const void *ctr, size_t ctrlen);
/* Retrieve the key length in bytes used with algorithm A. */
size_t gcry_cipher_get_algo_keylen (int algo);
/* Retrieve the block length in bytes used with algorithm A. */
size_t gcry_cipher_get_algo_blklen (int algo);
/* Return 0 if the algorithm A is available for use. */
#define gcry_cipher_test_algo(a) \
gcry_cipher_algo_info( (a), GCRYCTL_TEST_ALGO, NULL, NULL )
/************************************
* *
* Asymmetric Cipher Functions *
* *
************************************/
/* The algorithms and their IDs we support. */
enum gcry_pk_algos
{
GCRY_PK_RSA = 1, /* RSA */
GCRY_PK_RSA_E = 2, /* (deprecated: use 1). */
GCRY_PK_RSA_S = 3, /* (deprecated: use 1). */
GCRY_PK_ELG_E = 16, /* (deprecated: use 20). */
GCRY_PK_DSA = 17, /* Digital Signature Algorithm. */
GCRY_PK_ECC = 18, /* Generic ECC. */
GCRY_PK_ELG = 20, /* Elgamal */
GCRY_PK_ECDSA = 301, /* (only for external use). */
GCRY_PK_ECDH = 302, /* (only for external use). */
GCRY_PK_EDDSA = 303 /* (only for external use). */
};
/* Flags describing usage capabilities of a PK algorithm. */
#define GCRY_PK_USAGE_SIGN 1 /* Good for signatures. */
#define GCRY_PK_USAGE_ENCR 2 /* Good for encryption. */
#define GCRY_PK_USAGE_CERT 4 /* Good to certify other keys. */
#define GCRY_PK_USAGE_AUTH 8 /* Good for authentication. */
#define GCRY_PK_USAGE_UNKN 128 /* Unknown usage flag. */
/* Modes used with gcry_pubkey_get_sexp. */
#define GCRY_PK_GET_PUBKEY 1
#define GCRY_PK_GET_SECKEY 2
/* Encrypt the DATA using the public key PKEY and store the result as
a newly created S-expression at RESULT. */
gcry_error_t gcry_pk_encrypt (gcry_sexp_t *result,
gcry_sexp_t data, gcry_sexp_t pkey);
/* Decrypt the DATA using the private key SKEY and store the result as
a newly created S-expression at RESULT. */
gcry_error_t gcry_pk_decrypt (gcry_sexp_t *result,
gcry_sexp_t data, gcry_sexp_t skey);
/* Sign the DATA using the private key SKEY and store the result as
a newly created S-expression at RESULT. */
gcry_error_t gcry_pk_sign (gcry_sexp_t *result,
gcry_sexp_t data, gcry_sexp_t skey);
/* Check the signature SIGVAL on DATA using the public key PKEY. */
gcry_error_t gcry_pk_verify (gcry_sexp_t sigval,
gcry_sexp_t data, gcry_sexp_t pkey);
/* Check that private KEY is sane. */
gcry_error_t gcry_pk_testkey (gcry_sexp_t key);
/* Generate a new key pair according to the parameters given in
S_PARMS. The new key pair is returned in as an S-expression in
R_KEY. */
gcry_error_t gcry_pk_genkey (gcry_sexp_t *r_key, gcry_sexp_t s_parms);
/* Catch all function for miscellaneous operations. */
gcry_error_t gcry_pk_ctl (int cmd, void *buffer, size_t buflen);
/* Retrieve information about the public key algorithm ALGO. */
gcry_error_t gcry_pk_algo_info (int algo, int what,
void *buffer, size_t *nbytes);
/* Map the public key algorithm whose ID is contained in ALGORITHM to
a string representation of the algorithm name. For unknown
algorithm IDs this functions returns "?". */
const char *gcry_pk_algo_name (int algorithm) _GCRY_GCC_ATTR_PURE;
/* Map the algorithm NAME to a public key algorithm Id. Return 0 if
the algorithm name is not known. */
int gcry_pk_map_name (const char* name) _GCRY_GCC_ATTR_PURE;
/* Return what is commonly referred as the key length for the given
public or private KEY. */
unsigned int gcry_pk_get_nbits (gcry_sexp_t key) _GCRY_GCC_ATTR_PURE;
/* Return the so called KEYGRIP which is the SHA-1 hash of the public
key parameters expressed in a way depending on the algorithm. */
unsigned char *gcry_pk_get_keygrip (gcry_sexp_t key, unsigned char *array);
/* Return the name of the curve matching KEY. */
const char *gcry_pk_get_curve (gcry_sexp_t key, int iterator,
unsigned int *r_nbits);
/* Return an S-expression with the parameters of the named ECC curve
NAME. ALGO must be set to an ECC algorithm. */
gcry_sexp_t gcry_pk_get_param (int algo, const char *name);
/* Return 0 if the public key algorithm A is available for use. */
#define gcry_pk_test_algo(a) \
gcry_pk_algo_info( (a), GCRYCTL_TEST_ALGO, NULL, NULL )
/* Return an S-expression representing the context CTX. */
gcry_error_t gcry_pubkey_get_sexp (gcry_sexp_t *r_sexp,
int mode, gcry_ctx_t ctx);
/************************************
* *
* Cryptograhic Hash Functions *
* *
************************************/
/* Algorithm IDs for the hash functions we know about. Not all of them
are implemented. */
enum gcry_md_algos
{
GCRY_MD_NONE = 0,
GCRY_MD_MD5 = 1,
GCRY_MD_SHA1 = 2,
GCRY_MD_RMD160 = 3,
GCRY_MD_MD2 = 5,
GCRY_MD_TIGER = 6, /* TIGER/192 as used by gpg <= 1.3.2. */
GCRY_MD_HAVAL = 7, /* HAVAL, 5 pass, 160 bit. */
GCRY_MD_SHA256 = 8,
GCRY_MD_SHA384 = 9,
GCRY_MD_SHA512 = 10,
GCRY_MD_SHA224 = 11,
GCRY_MD_MD4 = 301,
GCRY_MD_CRC32 = 302,
GCRY_MD_CRC32_RFC1510 = 303,
GCRY_MD_CRC24_RFC2440 = 304,
GCRY_MD_WHIRLPOOL = 305,
GCRY_MD_TIGER1 = 306, /* TIGER fixed. */
GCRY_MD_TIGER2 = 307, /* TIGER2 variant. */
GCRY_MD_GOSTR3411_94 = 308, /* GOST R 34.11-94. */
GCRY_MD_STRIBOG256 = 309, /* GOST R 34.11-2012, 256 bit. */
GCRY_MD_STRIBOG512 = 310, /* GOST R 34.11-2012, 512 bit. */
GCRY_MD_GOSTR3411_CP = 311, /* GOST R 34.11-94 with CryptoPro-A S-Box. */
GCRY_MD_SHA3_224 = 312,
GCRY_MD_SHA3_256 = 313,
GCRY_MD_SHA3_384 = 314,
GCRY_MD_SHA3_512 = 315,
GCRY_MD_SHAKE128 = 316,
GCRY_MD_SHAKE256 = 317,
GCRY_MD_BLAKE2B_512 = 318,
GCRY_MD_BLAKE2B_384 = 319,
GCRY_MD_BLAKE2B_256 = 320,
GCRY_MD_BLAKE2B_160 = 321,
GCRY_MD_BLAKE2S_256 = 322,
GCRY_MD_BLAKE2S_224 = 323,
GCRY_MD_BLAKE2S_160 = 324,
GCRY_MD_BLAKE2S_128 = 325,
GCRY_MD_SM3 = 326,
};
/* Flags used with the open function. */
enum gcry_md_flags
{
GCRY_MD_FLAG_SECURE = 1, /* Allocate all buffers in "secure" memory. */
GCRY_MD_FLAG_HMAC = 2, /* Make an HMAC out of this algorithm. */
GCRY_MD_FLAG_BUGEMU1 = 0x0100
};
/* (Forward declaration.) */
struct gcry_md_context;
/* This object is used to hold a handle to a message digest object.
This structure is private - only to be used by the public gcry_md_*
macros. */
typedef struct gcry_md_handle
{
/* Actual context. */
struct gcry_md_context *ctx;
/* Buffer management. */
int bufpos;
int bufsize;
unsigned char buf[1];
} *gcry_md_hd_t;
/* Compatibility types, do not use them. */
#ifndef GCRYPT_NO_DEPRECATED
typedef struct gcry_md_handle *GCRY_MD_HD _GCRY_GCC_ATTR_DEPRECATED;
typedef struct gcry_md_handle *GcryMDHd _GCRY_GCC_ATTR_DEPRECATED;
#endif
/* Create a message digest object for algorithm ALGO. FLAGS may be
given as an bitwise OR of the gcry_md_flags values. ALGO may be
given as 0 if the algorithms to be used are later set using
gcry_md_enable. */
gcry_error_t gcry_md_open (gcry_md_hd_t *h, int algo, unsigned int flags);
/* Release the message digest object HD. */
void gcry_md_close (gcry_md_hd_t hd);
/* Add the message digest algorithm ALGO to the digest object HD. */
gcry_error_t gcry_md_enable (gcry_md_hd_t hd, int algo);
/* Create a new digest object as an exact copy of the object HD. */
gcry_error_t gcry_md_copy (gcry_md_hd_t *bhd, gcry_md_hd_t ahd);
/* Reset the digest object HD to its initial state. */
void gcry_md_reset (gcry_md_hd_t hd);
/* Perform various operations on the digest object HD. */
gcry_error_t gcry_md_ctl (gcry_md_hd_t hd, int cmd,
void *buffer, size_t buflen);
/* Pass LENGTH bytes of data in BUFFER to the digest object HD so that
it can update the digest values. This is the actual hash
function. */
void gcry_md_write (gcry_md_hd_t hd, const void *buffer, size_t length);
/* Read out the final digest from HD return the digest value for
algorithm ALGO. */
unsigned char *gcry_md_read (gcry_md_hd_t hd, int algo);
/* Read more output from algorithm ALGO to BUFFER of size LENGTH from
* digest object HD. Algorithm needs to be 'expendable-output function'. */
gpg_error_t gcry_md_extract (gcry_md_hd_t hd, int algo, void *buffer,
size_t length);
/* Convenience function to calculate the hash from the data in BUFFER
of size LENGTH using the algorithm ALGO avoiding the creating of a
hash object. The hash is returned in the caller provided buffer
DIGEST which must be large enough to hold the digest of the given
algorithm. */
void gcry_md_hash_buffer (int algo, void *digest,
const void *buffer, size_t length);
/* Convenience function to hash multiple buffers. */
gpg_error_t gcry_md_hash_buffers (int algo, unsigned int flags, void *digest,
const gcry_buffer_t *iov, int iovcnt);
/* Retrieve the algorithm used with HD. This does not work reliable
if more than one algorithm is enabled in HD. */
int gcry_md_get_algo (gcry_md_hd_t hd);
/* Retrieve the length in bytes of the digest yielded by algorithm
ALGO. */
unsigned int gcry_md_get_algo_dlen (int algo);
/* Return true if the the algorithm ALGO is enabled in the digest
object A. */
int gcry_md_is_enabled (gcry_md_hd_t a, int algo);
/* Return true if the digest object A is allocated in "secure" memory. */
int gcry_md_is_secure (gcry_md_hd_t a);
/* Deprecated: Use gcry_md_is_enabled or gcry_md_is_secure. */
gcry_error_t gcry_md_info (gcry_md_hd_t h, int what, void *buffer,
size_t *nbytes) _GCRY_ATTR_INTERNAL;
/* Retrieve various information about the algorithm ALGO. */
gcry_error_t gcry_md_algo_info (int algo, int what, void *buffer,
size_t *nbytes);
/* Map the digest algorithm id ALGO to a string representation of the
algorithm name. For unknown algorithms this function returns
"?". */
const char *gcry_md_algo_name (int algo) _GCRY_GCC_ATTR_PURE;
/* Map the algorithm NAME to a digest algorithm Id. Return 0 if
the algorithm name is not known. */
int gcry_md_map_name (const char* name) _GCRY_GCC_ATTR_PURE;
/* For use with the HMAC feature, the set MAC key to the KEY of
KEYLEN bytes. */
gcry_error_t gcry_md_setkey (gcry_md_hd_t hd, const void *key, size_t keylen);
/* Start or stop debugging for digest handle HD; i.e. create a file
named dbgmd-<n>.<suffix> while hashing. If SUFFIX is NULL,
debugging stops and the file will be closed. */
void gcry_md_debug (gcry_md_hd_t hd, const char *suffix);
/* Update the hash(s) of H with the character C. This is a buffered
version of the gcry_md_write function. */
#define gcry_md_putc(h,c) \
do { \
gcry_md_hd_t h__ = (h); \
if( (h__)->bufpos == (h__)->bufsize ) \
gcry_md_write( (h__), NULL, 0 ); \
(h__)->buf[(h__)->bufpos++] = (c) & 0xff; \
} while(0)
/* Finalize the digest calculation. This is not really needed because
gcry_md_read() does this implicitly. */
#define gcry_md_final(a) \
gcry_md_ctl ((a), GCRYCTL_FINALIZE, NULL, 0)
/* Return 0 if the algorithm A is available for use. */
#define gcry_md_test_algo(a) \
gcry_md_algo_info( (a), GCRYCTL_TEST_ALGO, NULL, NULL )
/* Return an DER encoded ASN.1 OID for the algorithm A in buffer B. N
must point to size_t variable with the available size of buffer B.
After return it will receive the actual size of the returned
OID. */
#define gcry_md_get_asnoid(a,b,n) \
gcry_md_algo_info((a), GCRYCTL_GET_ASNOID, (b), (n))
/**********************************************
* *
* Message Authentication Code Functions *
* *
**********************************************/
/* The data object used to hold a handle to an encryption object. */
struct gcry_mac_handle;
typedef struct gcry_mac_handle *gcry_mac_hd_t;
/* Algorithm IDs for the hash functions we know about. Not all of them
are implemented. */
enum gcry_mac_algos
{
GCRY_MAC_NONE = 0,
GCRY_MAC_HMAC_SHA256 = 101,
GCRY_MAC_HMAC_SHA224 = 102,
GCRY_MAC_HMAC_SHA512 = 103,
GCRY_MAC_HMAC_SHA384 = 104,
GCRY_MAC_HMAC_SHA1 = 105,
GCRY_MAC_HMAC_MD5 = 106,
GCRY_MAC_HMAC_MD4 = 107,
GCRY_MAC_HMAC_RMD160 = 108,
GCRY_MAC_HMAC_TIGER1 = 109, /* The fixed TIGER variant */
GCRY_MAC_HMAC_WHIRLPOOL = 110,
GCRY_MAC_HMAC_GOSTR3411_94 = 111,
GCRY_MAC_HMAC_STRIBOG256 = 112,
GCRY_MAC_HMAC_STRIBOG512 = 113,
GCRY_MAC_HMAC_MD2 = 114,
GCRY_MAC_HMAC_SHA3_224 = 115,
GCRY_MAC_HMAC_SHA3_256 = 116,
GCRY_MAC_HMAC_SHA3_384 = 117,
GCRY_MAC_HMAC_SHA3_512 = 118,
GCRY_MAC_CMAC_AES = 201,
GCRY_MAC_CMAC_3DES = 202,
GCRY_MAC_CMAC_CAMELLIA = 203,
GCRY_MAC_CMAC_CAST5 = 204,
GCRY_MAC_CMAC_BLOWFISH = 205,
GCRY_MAC_CMAC_TWOFISH = 206,
GCRY_MAC_CMAC_SERPENT = 207,
GCRY_MAC_CMAC_SEED = 208,
GCRY_MAC_CMAC_RFC2268 = 209,
GCRY_MAC_CMAC_IDEA = 210,
GCRY_MAC_CMAC_GOST28147 = 211,
GCRY_MAC_GMAC_AES = 401,
GCRY_MAC_GMAC_CAMELLIA = 402,
GCRY_MAC_GMAC_TWOFISH = 403,
GCRY_MAC_GMAC_SERPENT = 404,
GCRY_MAC_GMAC_SEED = 405,
GCRY_MAC_POLY1305 = 501,
GCRY_MAC_POLY1305_AES = 502,
GCRY_MAC_POLY1305_CAMELLIA = 503,
GCRY_MAC_POLY1305_TWOFISH = 504,
GCRY_MAC_POLY1305_SERPENT = 505,
GCRY_MAC_POLY1305_SEED = 506
};
/* Flags used with the open function. */
enum gcry_mac_flags
{
GCRY_MAC_FLAG_SECURE = 1 /* Allocate all buffers in "secure" memory. */
};
/* Create a MAC handle for algorithm ALGO. FLAGS may be given as an bitwise OR
of the gcry_mac_flags values. CTX maybe NULL or gcry_ctx_t object to be
associated with HANDLE. */
gcry_error_t gcry_mac_open (gcry_mac_hd_t *handle, int algo,
unsigned int flags, gcry_ctx_t ctx);
/* Close the MAC handle H and release all resource. */
void gcry_mac_close (gcry_mac_hd_t h);
/* Perform various operations on the MAC object H. */
gcry_error_t gcry_mac_ctl (gcry_mac_hd_t h, int cmd, void *buffer,
size_t buflen);
/* Retrieve various information about the MAC algorithm ALGO. */
gcry_error_t gcry_mac_algo_info (int algo, int what, void *buffer,
size_t *nbytes);
/* Set KEY of length KEYLEN bytes for the MAC handle HD. */
gcry_error_t gcry_mac_setkey (gcry_mac_hd_t hd, const void *key,
size_t keylen);
/* Set initialization vector IV of length IVLEN for the MAC handle HD. */
gcry_error_t gcry_mac_setiv (gcry_mac_hd_t hd, const void *iv,
size_t ivlen);
/* Pass LENGTH bytes of data in BUFFER to the MAC object HD so that
it can update the MAC values. */
gcry_error_t gcry_mac_write (gcry_mac_hd_t hd, const void *buffer,
size_t length);
/* Read out the final authentication code from the MAC object HD to BUFFER. */
gcry_error_t gcry_mac_read (gcry_mac_hd_t hd, void *buffer, size_t *buflen);
/* Verify the final authentication code from the MAC object HD with BUFFER. */
gcry_error_t gcry_mac_verify (gcry_mac_hd_t hd, const void *buffer,
size_t buflen);
/* Retrieve the algorithm used with MAC. */
int gcry_mac_get_algo (gcry_mac_hd_t hd);
/* Retrieve the length in bytes of the MAC yielded by algorithm ALGO. */
unsigned int gcry_mac_get_algo_maclen (int algo);
/* Retrieve the default key length in bytes used with algorithm A. */
unsigned int gcry_mac_get_algo_keylen (int algo);
/* Map the MAC algorithm whose ID is contained in ALGORITHM to a
string representation of the algorithm name. For unknown algorithm
IDs this function returns "?". */
const char *gcry_mac_algo_name (int algorithm) _GCRY_GCC_ATTR_PURE;
/* Map the algorithm name NAME to an MAC algorithm ID. Return 0 if
the algorithm name is not known. */
int gcry_mac_map_name (const char *name) _GCRY_GCC_ATTR_PURE;
/* Reset the handle to the state after open/setkey. */
#define gcry_mac_reset(h) gcry_mac_ctl ((h), GCRYCTL_RESET, NULL, 0)
/* Return 0 if the algorithm A is available for use. */
#define gcry_mac_test_algo(a) \
gcry_mac_algo_info( (a), GCRYCTL_TEST_ALGO, NULL, NULL )
/******************************
* *
* Key Derivation Functions *
* *
******************************/
/* Algorithm IDs for the KDFs. */
enum gcry_kdf_algos
{
GCRY_KDF_NONE = 0,
GCRY_KDF_SIMPLE_S2K = 16,
GCRY_KDF_SALTED_S2K = 17,
GCRY_KDF_ITERSALTED_S2K = 19,
GCRY_KDF_PBKDF1 = 33,
GCRY_KDF_PBKDF2 = 34,
GCRY_KDF_SCRYPT = 48
};
/* Derive a key from a passphrase. */
gpg_error_t gcry_kdf_derive (const void *passphrase, size_t passphraselen,
int algo, int subalgo,
const void *salt, size_t saltlen,
unsigned long iterations,
size_t keysize, void *keybuffer);
/************************************
* *
* Random Generating Functions *
* *
************************************/
/* The type of the random number generator. */
enum gcry_rng_types
{
GCRY_RNG_TYPE_STANDARD = 1, /* The default CSPRNG generator. */
GCRY_RNG_TYPE_FIPS = 2, /* The FIPS X9.31 AES generator. */
GCRY_RNG_TYPE_SYSTEM = 3 /* The system's native generator. */
};
/* The possible values for the random quality. The rule of thumb is
to use STRONG for session keys and VERY_STRONG for key material.
WEAK is usually an alias for STRONG and should not be used anymore
(except with gcry_mpi_randomize); use gcry_create_nonce instead. */
typedef enum gcry_random_level
{
GCRY_WEAK_RANDOM = 0,
GCRY_STRONG_RANDOM = 1,
GCRY_VERY_STRONG_RANDOM = 2
}
gcry_random_level_t;
/* Fill BUFFER with LENGTH bytes of random, using random numbers of
quality LEVEL. */
void gcry_randomize (void *buffer, size_t length,
enum gcry_random_level level);
/* Add the external random from BUFFER with LENGTH bytes into the
pool. QUALITY should either be -1 for unknown or in the range of 0
to 100 */
gcry_error_t gcry_random_add_bytes (const void *buffer, size_t length,
int quality);
/* If random numbers are used in an application, this macro should be
called from time to time so that new stuff gets added to the
internal pool of the RNG. */
#define gcry_fast_random_poll() gcry_control (GCRYCTL_FAST_POLL, NULL)
/* Return NBYTES of allocated random using a random numbers of quality
LEVEL. */
void *gcry_random_bytes (size_t nbytes, enum gcry_random_level level)
_GCRY_GCC_ATTR_MALLOC;
/* Return NBYTES of allocated random using a random numbers of quality
LEVEL. The random numbers are created returned in "secure"
memory. */
void *gcry_random_bytes_secure (size_t nbytes, enum gcry_random_level level)
_GCRY_GCC_ATTR_MALLOC;
/* Set the big integer W to a random value of NBITS using a random
generator with quality LEVEL. Note that by using a level of
GCRY_WEAK_RANDOM gcry_create_nonce is used internally. */
void gcry_mpi_randomize (gcry_mpi_t w,
unsigned int nbits, enum gcry_random_level level);
/* Create an unpredicable nonce of LENGTH bytes in BUFFER. */
void gcry_create_nonce (void *buffer, size_t length);
/*******************************/
/* */
/* Prime Number Functions */
/* */
/*******************************/
/* Mode values passed to a gcry_prime_check_func_t. */
#define GCRY_PRIME_CHECK_AT_FINISH 0
#define GCRY_PRIME_CHECK_AT_GOT_PRIME 1
#define GCRY_PRIME_CHECK_AT_MAYBE_PRIME 2
/* The function should return 1 if the operation shall continue, 0 to
reject the prime candidate. */
typedef int (*gcry_prime_check_func_t) (void *arg, int mode,
gcry_mpi_t candidate);
/* Flags for gcry_prime_generate(): */
/* Allocate prime numbers and factors in secure memory. */
#define GCRY_PRIME_FLAG_SECRET (1 << 0)
/* Make sure that at least one prime factor is of size
`FACTOR_BITS'. */
#define GCRY_PRIME_FLAG_SPECIAL_FACTOR (1 << 1)
/* Generate a new prime number of PRIME_BITS bits and store it in
PRIME. If FACTOR_BITS is non-zero, one of the prime factors of
(prime - 1) / 2 must be FACTOR_BITS bits long. If FACTORS is
non-zero, allocate a new, NULL-terminated array holding the prime
factors and store it in FACTORS. FLAGS might be used to influence
the prime number generation process. */
gcry_error_t gcry_prime_generate (gcry_mpi_t *prime,
unsigned int prime_bits,
unsigned int factor_bits,
gcry_mpi_t **factors,
gcry_prime_check_func_t cb_func,
void *cb_arg,
gcry_random_level_t random_level,
unsigned int flags);
/* Find a generator for PRIME where the factorization of (prime-1) is
in the NULL terminated array FACTORS. Return the generator as a
newly allocated MPI in R_G. If START_G is not NULL, use this as
the start for the search. */
gcry_error_t gcry_prime_group_generator (gcry_mpi_t *r_g,
gcry_mpi_t prime,
gcry_mpi_t *factors,
gcry_mpi_t start_g);
/* Convenience function to release the FACTORS array. */
void gcry_prime_release_factors (gcry_mpi_t *factors);
/* Check whether the number X is prime. */
gcry_error_t gcry_prime_check (gcry_mpi_t x, unsigned int flags);
/************************************
* *
* Miscellaneous Stuff *
* *
************************************/
/* Release the context object CTX. */
void gcry_ctx_release (gcry_ctx_t ctx);
/* Log data using Libgcrypt's own log interface. */
void gcry_log_debug (const char *fmt, ...) _GCRY_GCC_ATTR_PRINTF(1,2);
void gcry_log_debughex (const char *text, const void *buffer, size_t length);
void gcry_log_debugmpi (const char *text, gcry_mpi_t mpi);
void gcry_log_debugpnt (const char *text,
gcry_mpi_point_t point, gcry_ctx_t ctx);
void gcry_log_debugsxp (const char *text, gcry_sexp_t sexp);
char *gcry_get_config (int mode, const char *what);
/* Log levels used by the internal logging facility. */
enum gcry_log_levels
{
GCRY_LOG_CONT = 0, /* (Continue the last log line.) */
GCRY_LOG_INFO = 10,
GCRY_LOG_WARN = 20,
GCRY_LOG_ERROR = 30,
GCRY_LOG_FATAL = 40,
GCRY_LOG_BUG = 50,
GCRY_LOG_DEBUG = 100
};
/* Type for progress handlers. */
typedef void (*gcry_handler_progress_t) (void *, const char *, int, int, int);
/* Type for memory allocation handlers. */
typedef void *(*gcry_handler_alloc_t) (size_t n);
/* Type for secure memory check handlers. */
typedef int (*gcry_handler_secure_check_t) (const void *);
/* Type for memory reallocation handlers. */
typedef void *(*gcry_handler_realloc_t) (void *p, size_t n);
/* Type for memory free handlers. */
typedef void (*gcry_handler_free_t) (void *);
/* Type for out-of-memory handlers. */
typedef int (*gcry_handler_no_mem_t) (void *, size_t, unsigned int);
/* Type for fatal error handlers. */
typedef void (*gcry_handler_error_t) (void *, int, const char *);
/* Type for logging handlers. */
typedef void (*gcry_handler_log_t) (void *, int, const char *, va_list);
/* Certain operations can provide progress information. This function
is used to register a handler for retrieving these information. */
void gcry_set_progress_handler (gcry_handler_progress_t cb, void *cb_data);
/* Register a custom memory allocation functions. */
void gcry_set_allocation_handler (
gcry_handler_alloc_t func_alloc,
gcry_handler_alloc_t func_alloc_secure,
gcry_handler_secure_check_t func_secure_check,
gcry_handler_realloc_t func_realloc,
gcry_handler_free_t func_free);
/* Register a function used instead of the internal out of memory
handler. */
void gcry_set_outofcore_handler (gcry_handler_no_mem_t h, void *opaque);
/* Register a function used instead of the internal fatal error
handler. */
void gcry_set_fatalerror_handler (gcry_handler_error_t fnc, void *opaque);
/* Register a function used instead of the internal logging
facility. */
void gcry_set_log_handler (gcry_handler_log_t f, void *opaque);
/* Reserved for future use. */
void gcry_set_gettext_handler (const char *(*f)(const char*));
/* Libgcrypt uses its own memory allocation. It is important to use
gcry_free () to release memory allocated by libgcrypt. */
void *gcry_malloc (size_t n) _GCRY_GCC_ATTR_MALLOC;
void *gcry_calloc (size_t n, size_t m) _GCRY_GCC_ATTR_MALLOC;
void *gcry_malloc_secure (size_t n) _GCRY_GCC_ATTR_MALLOC;
void *gcry_calloc_secure (size_t n, size_t m) _GCRY_GCC_ATTR_MALLOC;
void *gcry_realloc (void *a, size_t n);
char *gcry_strdup (const char *string) _GCRY_GCC_ATTR_MALLOC;
void *gcry_xmalloc (size_t n) _GCRY_GCC_ATTR_MALLOC;
void *gcry_xcalloc (size_t n, size_t m) _GCRY_GCC_ATTR_MALLOC;
void *gcry_xmalloc_secure (size_t n) _GCRY_GCC_ATTR_MALLOC;
void *gcry_xcalloc_secure (size_t n, size_t m) _GCRY_GCC_ATTR_MALLOC;
void *gcry_xrealloc (void *a, size_t n);
char *gcry_xstrdup (const char * a) _GCRY_GCC_ATTR_MALLOC;
void gcry_free (void *a);
/* Return true if A is allocated in "secure" memory. */
int gcry_is_secure (const void *a) _GCRY_GCC_ATTR_PURE;
/* Return true if Libgcrypt is in FIPS mode. */
#define gcry_fips_mode_active() !!gcry_control (GCRYCTL_FIPS_MODE_P, 0)
#if 0 /* (Keep Emacsens' auto-indent happy.) */
{
#endif
#ifdef __cplusplus
}
#endif
#endif /* _GCRYPT_H */
/*
@emacs_local_vars_begin@
@emacs_local_vars_read_only@
@emacs_local_vars_end@
*/
diff --git a/src/global.c b/src/global.c
index ad9ab1df..6c2486c4 100644
--- a/src/global.c
+++ b/src/global.c
@@ -1,1339 +1,1343 @@
/* global.c - global control functions
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
* 2004, 2005, 2006, 2008, 2011,
* 2012 Free Software Foundation, Inc.
* Copyright (C) 2013, 2014, 2017 g10 Code GmbH
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser general Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <ctype.h>
#include <limits.h>
#include <errno.h>
#include <unistd.h>
#ifdef HAVE_SYSLOG
# include <syslog.h>
#endif /*HAVE_SYSLOG*/
#include "g10lib.h"
#include "gcrypt-testapi.h"
#include "cipher.h"
#include "stdmem.h" /* our own memory allocator */
#include "secmem.h" /* our own secmem allocator */
/****************
* flag bits: 0 : general cipher debug
* 1 : general MPI debug
*/
static unsigned int debug_flags;
/* gcry_control (GCRYCTL_SET_FIPS_MODE), sets this flag so that the
initialization code switched fips mode on. */
static int force_fips_mode;
/* Controlled by global_init(). */
static int any_init_done;
/*
* Functions called before and after blocking syscalls.
* Initialized by global_init and used via
* _gcry_pre_syscall and _gcry_post_syscall.
*/
static void (*pre_syscall_func)(void);
static void (*post_syscall_func)(void);
/* Memory management. */
static gcry_handler_alloc_t alloc_func;
static gcry_handler_alloc_t alloc_secure_func;
static gcry_handler_secure_check_t is_secure_func;
static gcry_handler_realloc_t realloc_func;
static gcry_handler_free_t free_func;
static gcry_handler_no_mem_t outofcore_handler;
static void *outofcore_handler_value;
static int no_secure_memory;
/* Prototypes. */
static gpg_err_code_t external_lock_test (int cmd);
/* This is our handmade constructor. It gets called by any function
likely to be called at startup. The suggested way for an
application to make sure that this has been called is by using
gcry_check_version. */
static void
global_init (void)
{
gcry_error_t err = 0;
if (any_init_done)
return;
any_init_done = 1;
/* Tell the random module that we have seen an init call. */
_gcry_set_preferred_rng_type (0);
/* Get the system call clamp functions. */
if (!pre_syscall_func)
gpgrt_get_syscall_clamp (&pre_syscall_func, &post_syscall_func);
/* See whether the system is in FIPS mode. This needs to come as
early as possible but after ATH has been initialized. */
_gcry_initialize_fips_mode (force_fips_mode);
/* Before we do any other initialization we need to test available
hardware features. */
_gcry_detect_hw_features ();
/* Initialize the modules - this is mainly allocating some memory and
creating mutexes. */
err = _gcry_cipher_init ();
if (err)
goto fail;
err = _gcry_md_init ();
if (err)
goto fail;
err = _gcry_mac_init ();
if (err)
goto fail;
err = _gcry_pk_init ();
if (err)
goto fail;
err = _gcry_primegen_init ();
if (err)
goto fail;
err = _gcry_secmem_module_init ();
if (err)
goto fail;
err = _gcry_mpi_init ();
if (err)
goto fail;
return;
fail:
BUG ();
}
/* This function is called by the macro fips_is_operational and makes
sure that the minimal initialization has been done. This is far
from a perfect solution and hides problems with an improper
initialization but at least in single-threaded mode it should work
reliable.
The reason we need this is that a lot of applications don't use
Libgcrypt properly by not running any initialization code at all.
They just call a Libgcrypt function and that is all what they want.
Now with the FIPS mode, that has the side effect of entering FIPS
mode (for security reasons, FIPS mode is the default if no
initialization has been done) and bailing out immediately because
the FSM is in the wrong state. If we always run the init code,
Libgcrypt can test for FIPS mode and at least if not in FIPS mode,
it will behave as before. Note that this on-the-fly initialization
is only done for the cryptographic functions subject to FIPS mode
and thus not all API calls will do such an initialization. */
int
_gcry_global_is_operational (void)
{
if (!any_init_done)
{
#ifdef HAVE_SYSLOG
syslog (LOG_USER|LOG_WARNING, "Libgcrypt warning: "
"missing initialization - please fix the application");
#endif /*HAVE_SYSLOG*/
global_init ();
}
return _gcry_fips_is_operational ();
}
/* Version number parsing. */
/* This function parses the first portion of the version number S and
stores it in *NUMBER. On success, this function returns a pointer
into S starting with the first character, which is not part of the
initial number portion; on failure, NULL is returned. */
static const char*
parse_version_number( const char *s, int *number )
{
int val = 0;
if( *s == '0' && isdigit(s[1]) )
return NULL; /* leading zeros are not allowed */
for ( ; isdigit(*s); s++ ) {
val *= 10;
val += *s - '0';
}
*number = val;
return val < 0? NULL : s;
}
/* This function breaks up the complete string-representation of the
version number S, which is of the following struture: <major
number>.<minor number>.<micro number><patch level>. The major,
minor and micro number components will be stored in *MAJOR, *MINOR
and *MICRO.
On success, the last component, the patch level, will be returned;
in failure, NULL will be returned. */
static const char *
parse_version_string( const char *s, int *major, int *minor, int *micro )
{
s = parse_version_number( s, major );
if( !s || *s != '.' )
return NULL;
s++;
s = parse_version_number( s, minor );
if( !s || *s != '.' )
return NULL;
s++;
s = parse_version_number( s, micro );
if( !s )
return NULL;
return s; /* patchlevel */
}
/* If REQ_VERSION is non-NULL, check that the version of the library
is at minimum the requested one. Returns the string representation
of the library version if the condition is satisfied; return NULL
if the requested version is newer than that of the library.
If a NULL is passed to this function, no check is done, but the
string representation of the library is simply returned. */
const char *
_gcry_check_version (const char *req_version)
{
const char *ver = VERSION;
int my_major, my_minor, my_micro;
int rq_major, rq_minor, rq_micro;
const char *my_plvl;
if (req_version && req_version[0] == 1 && req_version[1] == 1)
return _gcry_compat_identification ();
/* Initialize library. */
global_init ();
if ( !req_version )
/* Caller wants our version number. */
return ver;
/* Parse own version number. */
my_plvl = parse_version_string( ver, &my_major, &my_minor, &my_micro );
if ( !my_plvl )
/* very strange our own version is bogus. Shouldn't we use
assert() here and bail out in case this happens? -mo. */
return NULL;
/* Parse requested version number. */
if (!parse_version_string (req_version, &rq_major, &rq_minor, &rq_micro))
return NULL; /* req version string is invalid, this can happen. */
/* Compare version numbers. */
if ( my_major > rq_major
|| (my_major == rq_major && my_minor > rq_minor)
|| (my_major == rq_major && my_minor == rq_minor && my_micro > rq_micro)
|| (my_major == rq_major && my_minor == rq_minor
&& my_micro == rq_micro))
{
return ver;
}
return NULL;
}
static void
print_config (const char *what, gpgrt_stream_t fp)
{
int i;
const char *s;
if (!what || !strcmp (what, "version"))
{
gpgrt_fprintf (fp, "version:%s:%x:%s:%x:\n",
VERSION, GCRYPT_VERSION_NUMBER,
GPGRT_VERSION, GPGRT_VERSION_NUMBER);
}
if (!what || !strcmp (what, "cc"))
{
gpgrt_fprintf (fp, "cc:%d:%s:\n",
#if GPGRT_VERSION_NUMBER >= 0x011b00 /* 1.27 */
GPGRT_GCC_VERSION
#else
_GPG_ERR_GCC_VERSION /* Due to a bug in gpg-error.h. */
#endif
,
#ifdef __clang__
"clang:" __VERSION__
#elif __GNUC__
"gcc:" __VERSION__
#else
":"
#endif
);
}
if (!what || !strcmp (what, "ciphers"))
gpgrt_fprintf (fp, "ciphers:%s:\n", LIBGCRYPT_CIPHERS);
if (!what || !strcmp (what, "pubkeys"))
gpgrt_fprintf (fp, "pubkeys:%s:\n", LIBGCRYPT_PUBKEY_CIPHERS);
if (!what || !strcmp (what, "digests"))
gpgrt_fprintf (fp, "digests:%s:\n", LIBGCRYPT_DIGESTS);
if (!what || !strcmp (what, "rnd-mod"))
{
gpgrt_fprintf (fp, "rnd-mod:"
#if USE_RNDEGD
"egd:"
#endif
#if USE_RNDLINUX
"linux:"
#endif
#if USE_RNDUNIX
"unix:"
#endif
#if USE_RNDW32
"w32:"
#endif
"\n");
}
if (!what || !strcmp (what, "cpu-arch"))
{
gpgrt_fprintf (fp, "cpu-arch:"
#if defined(HAVE_CPU_ARCH_X86)
"x86"
#elif defined(HAVE_CPU_ARCH_ALPHA)
"alpha"
#elif defined(HAVE_CPU_ARCH_SPARC)
"sparc"
#elif defined(HAVE_CPU_ARCH_MIPS)
"mips"
#elif defined(HAVE_CPU_ARCH_M68K)
"m68k"
#elif defined(HAVE_CPU_ARCH_PPC)
"ppc"
#elif defined(HAVE_CPU_ARCH_ARM)
"arm"
#endif
":\n");
}
if (!what || !strcmp (what, "mpi-asm"))
gpgrt_fprintf (fp, "mpi-asm:%s:\n", _gcry_mpi_get_hw_config ());
if (!what || !strcmp (what, "hwflist"))
{
unsigned int hwfeatures, afeature;
hwfeatures = _gcry_get_hw_features ();
gpgrt_fprintf (fp, "hwflist:");
for (i=0; (s = _gcry_enum_hw_features (i, &afeature)); i++)
if ((hwfeatures & afeature))
gpgrt_fprintf (fp, "%s:", s);
gpgrt_fprintf (fp, "\n");
}
if (!what || !strcmp (what, "fips-mode"))
{
/* We use y/n instead of 1/0 for the stupid reason that
* Emacsen's compile error parser would accidentally flag that
* line when printed during "make check" as an error. */
gpgrt_fprintf (fp, "fips-mode:%c:%c:\n",
fips_mode ()? 'y':'n',
_gcry_enforced_fips_mode ()? 'y':'n' );
}
if (!what || !strcmp (what, "rng-type"))
{
/* The currently used RNG type. */
unsigned int jver;
int active;
i = _gcry_get_rng_type (0);
switch (i)
{
case GCRY_RNG_TYPE_STANDARD: s = "standard"; break;
case GCRY_RNG_TYPE_FIPS: s = "fips"; break;
case GCRY_RNG_TYPE_SYSTEM: s = "system"; break;
default: BUG ();
}
jver = _gcry_rndjent_get_version (&active);
gpgrt_fprintf (fp, "rng-type:%s:%d:%u:%d:\n", s, i, jver, active);
}
}
/* With a MODE of 0 return a malloced string with configured features.
* In that case a WHAT of NULL returns everything in the same way
* GCRYCTL_PRINT_CONFIG would do. With a specific WHAT string only
* the requested feature is returned (w/o the trailing LF. On error
* NULL is returned. */
char *
_gcry_get_config (int mode, const char *what)
{
gpgrt_stream_t fp;
int save_errno;
void *data;
char *p;
if (mode)
{
gpg_err_set_errno (EINVAL);
return NULL;
}
fp = gpgrt_fopenmem (0, "w+b,samethread");
if (!fp)
return NULL;
print_config (what, fp);
if (gpgrt_ferror (fp))
{
save_errno = errno;
gpgrt_fclose (fp);
gpg_err_set_errno (save_errno);
return NULL;
}
gpgrt_rewind (fp);
if (gpgrt_fclose_snatch (fp, &data, NULL))
{
save_errno = errno;
gpgrt_fclose (fp);
gpg_err_set_errno (save_errno);
return NULL;
}
if (!data)
{
/* Nothing was printed (unknown value for WHAT). This is okay,
* so clear ERRNO to indicate this. */
gpg_err_set_errno (0);
return NULL;
}
/* Strip trailing LF. */
if (what && (p = strchr (data, '\n')))
*p = 0;
return data;
}
/* Command dispatcher function, acting as general control
function. */
gcry_err_code_t
_gcry_vcontrol (enum gcry_ctl_cmds cmd, va_list arg_ptr)
{
static int init_finished = 0;
gcry_err_code_t rc = 0;
switch (cmd)
{
case GCRYCTL_ENABLE_M_GUARD:
_gcry_private_enable_m_guard ();
break;
case GCRYCTL_ENABLE_QUICK_RANDOM:
_gcry_set_preferred_rng_type (0);
_gcry_enable_quick_random_gen ();
break;
case GCRYCTL_FAKED_RANDOM_P:
/* Return an error if the RNG is faked one (e.g. enabled by
ENABLE_QUICK_RANDOM. */
if (_gcry_random_is_faked ())
rc = GPG_ERR_GENERAL; /* Use as TRUE value. */
break;
case GCRYCTL_DUMP_RANDOM_STATS:
_gcry_random_dump_stats ();
break;
case GCRYCTL_DUMP_MEMORY_STATS:
/*m_print_stats("[fixme: prefix]");*/
break;
case GCRYCTL_DUMP_SECMEM_STATS:
_gcry_secmem_dump_stats (0);
break;
case GCRYCTL_DROP_PRIVS:
global_init ();
_gcry_secmem_init (0);
break;
case GCRYCTL_DISABLE_SECMEM:
global_init ();
no_secure_memory = 1;
break;
case GCRYCTL_INIT_SECMEM:
global_init ();
_gcry_secmem_init (va_arg (arg_ptr, unsigned int));
if ((_gcry_secmem_get_flags () & GCRY_SECMEM_FLAG_NOT_LOCKED))
rc = GPG_ERR_GENERAL;
break;
case GCRYCTL_TERM_SECMEM:
global_init ();
_gcry_secmem_term ();
break;
case GCRYCTL_DISABLE_SECMEM_WARN:
_gcry_set_preferred_rng_type (0);
_gcry_secmem_set_flags ((_gcry_secmem_get_flags ()
| GCRY_SECMEM_FLAG_NO_WARNING));
break;
case GCRYCTL_SUSPEND_SECMEM_WARN:
_gcry_set_preferred_rng_type (0);
_gcry_secmem_set_flags ((_gcry_secmem_get_flags ()
| GCRY_SECMEM_FLAG_SUSPEND_WARNING));
break;
case GCRYCTL_RESUME_SECMEM_WARN:
_gcry_set_preferred_rng_type (0);
_gcry_secmem_set_flags ((_gcry_secmem_get_flags ()
& ~GCRY_SECMEM_FLAG_SUSPEND_WARNING));
break;
+ case GCRYCTL_AUTO_EXPAND_SECMEM:
+ _gcry_secmem_set_auto_expand (va_arg (arg_ptr, unsigned int));
+ break;
+
case GCRYCTL_USE_SECURE_RNDPOOL:
global_init ();
_gcry_secure_random_alloc (); /* Put random number into secure memory. */
break;
case GCRYCTL_SET_RANDOM_SEED_FILE:
_gcry_set_preferred_rng_type (0);
_gcry_set_random_seed_file (va_arg (arg_ptr, const char *));
break;
case GCRYCTL_UPDATE_RANDOM_SEED_FILE:
_gcry_set_preferred_rng_type (0);
if ( fips_is_operational () )
_gcry_update_random_seed_file ();
break;
case GCRYCTL_SET_VERBOSITY:
_gcry_set_preferred_rng_type (0);
_gcry_set_log_verbosity (va_arg (arg_ptr, int));
break;
case GCRYCTL_SET_DEBUG_FLAGS:
debug_flags |= va_arg (arg_ptr, unsigned int);
break;
case GCRYCTL_CLEAR_DEBUG_FLAGS:
debug_flags &= ~va_arg (arg_ptr, unsigned int);
break;
case GCRYCTL_DISABLE_INTERNAL_LOCKING:
/* Not used anymore. */
global_init ();
break;
case GCRYCTL_ANY_INITIALIZATION_P:
if (any_init_done)
rc = GPG_ERR_GENERAL;
break;
case GCRYCTL_INITIALIZATION_FINISHED_P:
if (init_finished)
rc = GPG_ERR_GENERAL; /* Yes. */
break;
case GCRYCTL_INITIALIZATION_FINISHED:
/* This is a hook which should be used by an application after
all initialization has been done and right before any threads
are started. It is not really needed but the only way to be
really sure that all initialization for thread-safety has
been done. */
if (! init_finished)
{
global_init ();
/* Do only a basic random initialization, i.e. init the
mutexes. */
_gcry_random_initialize (0);
init_finished = 1;
/* Force us into operational state if in FIPS mode. */
(void)fips_is_operational ();
}
break;
case GCRYCTL_SET_THREAD_CBS:
/* This is now a dummy call. We used to install our own thread
library here. */
_gcry_set_preferred_rng_type (0);
global_init ();
break;
case GCRYCTL_FAST_POLL:
_gcry_set_preferred_rng_type (0);
/* We need to do make sure that the random pool is really
initialized so that the poll function is not a NOP. */
_gcry_random_initialize (1);
if ( fips_is_operational () )
_gcry_fast_random_poll ();
break;
case GCRYCTL_SET_RNDEGD_SOCKET:
#if USE_RNDEGD
_gcry_set_preferred_rng_type (0);
rc = _gcry_rndegd_set_socket_name (va_arg (arg_ptr, const char *));
#else
rc = GPG_ERR_NOT_SUPPORTED;
#endif
break;
case GCRYCTL_SET_RANDOM_DAEMON_SOCKET:
_gcry_set_preferred_rng_type (0);
_gcry_set_random_daemon_socket (va_arg (arg_ptr, const char *));
break;
case GCRYCTL_USE_RANDOM_DAEMON:
/* We need to do make sure that the random pool is really
initialized so that the poll function is not a NOP. */
_gcry_set_preferred_rng_type (0);
_gcry_random_initialize (1);
_gcry_use_random_daemon (!! va_arg (arg_ptr, int));
break;
case GCRYCTL_CLOSE_RANDOM_DEVICE:
_gcry_random_close_fds ();
break;
/* This command dumps information pertaining to the
configuration of libgcrypt to the given stream. It may be
used before the initialization has been finished but not
before a gcry_version_check. See also gcry_get_config. */
case GCRYCTL_PRINT_CONFIG:
{
FILE *fp = va_arg (arg_ptr, FILE *);
char *tmpstr;
_gcry_set_preferred_rng_type (0);
tmpstr = _gcry_get_config (0, NULL);
if (tmpstr)
{
if (fp)
fputs (tmpstr, fp);
else
log_info ("%s", tmpstr);
xfree (tmpstr);
}
}
break;
case GCRYCTL_OPERATIONAL_P:
/* Returns true if the library is in an operational state. This
is always true for non-fips mode. */
_gcry_set_preferred_rng_type (0);
if (_gcry_fips_test_operational ())
rc = GPG_ERR_GENERAL; /* Used as TRUE value */
break;
case GCRYCTL_FIPS_MODE_P:
if (fips_mode ()
&& !_gcry_is_fips_mode_inactive ()
&& !no_secure_memory)
rc = GPG_ERR_GENERAL; /* Used as TRUE value */
break;
case GCRYCTL_FORCE_FIPS_MODE:
/* Performing this command puts the library into fips mode. If
the library has already been initialized into fips mode, a
selftest is triggered. It is not possible to put the libraty
into fips mode after having passed the initialization. */
_gcry_set_preferred_rng_type (0);
if (!any_init_done)
{
/* Not yet initialized at all. Set a flag so that we are put
into fips mode during initialization. */
force_fips_mode = 1;
}
else
{
/* Already initialized. If we are already operational we
run a selftest. If not we use the is_operational call to
force us into operational state if possible. */
if (_gcry_fips_test_error_or_operational ())
_gcry_fips_run_selftests (1);
if (_gcry_fips_is_operational ())
rc = GPG_ERR_GENERAL; /* Used as TRUE value */
}
break;
case GCRYCTL_SELFTEST:
/* Run a selftest. This works in fips mode as well as in
standard mode. In contrast to the power-up tests, we use an
extended version of the selftests. Returns 0 on success or an
error code. */
global_init ();
rc = _gcry_fips_run_selftests (1);
break;
#if _GCRY_GCC_VERSION >= 40200
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wswitch"
#endif
case PRIV_CTL_INIT_EXTRNG_TEST: /* Init external random test. */
rc = GPG_ERR_NOT_SUPPORTED;
break;
case PRIV_CTL_RUN_EXTRNG_TEST: /* Run external DRBG test. */
{
struct gcry_drbg_test_vector *test =
va_arg (arg_ptr, struct gcry_drbg_test_vector *);
unsigned char *buf = va_arg (arg_ptr, unsigned char *);
if (buf)
rc = _gcry_rngdrbg_cavs_test (test, buf);
else
rc = _gcry_rngdrbg_healthcheck_one (test);
}
break;
case PRIV_CTL_DEINIT_EXTRNG_TEST: /* Deinit external random test. */
rc = GPG_ERR_NOT_SUPPORTED;
break;
case PRIV_CTL_EXTERNAL_LOCK_TEST: /* Run external lock test */
rc = external_lock_test (va_arg (arg_ptr, int));
break;
case PRIV_CTL_DUMP_SECMEM_STATS:
_gcry_secmem_dump_stats (1);
break;
#if _GCRY_GCC_VERSION >= 40200
# pragma GCC diagnostic pop
#endif
case GCRYCTL_DISABLE_HWF:
{
const char *name = va_arg (arg_ptr, const char *);
rc = _gcry_disable_hw_feature (name);
}
break;
case GCRYCTL_SET_ENFORCED_FIPS_FLAG:
if (!any_init_done)
{
/* Not yet initialized at all. Set the enforced fips mode flag */
_gcry_set_preferred_rng_type (0);
_gcry_set_enforced_fips_mode ();
}
else
rc = GPG_ERR_GENERAL;
break;
case GCRYCTL_SET_PREFERRED_RNG_TYPE:
/* This may be called before gcry_check_version. */
{
int i = va_arg (arg_ptr, int);
/* Note that we may not pass 0 to _gcry_set_preferred_rng_type. */
if (i > 0)
_gcry_set_preferred_rng_type (i);
}
break;
case GCRYCTL_GET_CURRENT_RNG_TYPE:
{
int *ip = va_arg (arg_ptr, int*);
if (ip)
*ip = _gcry_get_rng_type (!any_init_done);
}
break;
case GCRYCTL_DISABLE_LOCKED_SECMEM:
_gcry_set_preferred_rng_type (0);
_gcry_secmem_set_flags ((_gcry_secmem_get_flags ()
| GCRY_SECMEM_FLAG_NO_MLOCK));
break;
case GCRYCTL_DISABLE_PRIV_DROP:
_gcry_set_preferred_rng_type (0);
_gcry_secmem_set_flags ((_gcry_secmem_get_flags ()
| GCRY_SECMEM_FLAG_NO_PRIV_DROP));
break;
case GCRYCTL_INACTIVATE_FIPS_FLAG:
case GCRYCTL_REACTIVATE_FIPS_FLAG:
rc = GPG_ERR_NOT_IMPLEMENTED;
break;
case GCRYCTL_DRBG_REINIT:
{
const char *flagstr = va_arg (arg_ptr, const char *);
gcry_buffer_t *pers = va_arg (arg_ptr, gcry_buffer_t *);
int npers = va_arg (arg_ptr, int);
if (va_arg (arg_ptr, void *) || npers < 0)
rc = GPG_ERR_INV_ARG;
else if (_gcry_get_rng_type (!any_init_done) != GCRY_RNG_TYPE_FIPS)
rc = GPG_ERR_NOT_SUPPORTED;
else
rc = _gcry_rngdrbg_reinit (flagstr, pers, npers);
}
break;
case GCRYCTL_REINIT_SYSCALL_CLAMP:
if (!pre_syscall_func)
gpgrt_get_syscall_clamp (&pre_syscall_func, &post_syscall_func);
break;
default:
_gcry_set_preferred_rng_type (0);
rc = GPG_ERR_INV_OP;
}
return rc;
}
/* Set custom allocation handlers. This is in general not useful
* because the libgcrypt allocation functions are guaranteed to
* provide proper allocation handlers which zeroize memory if needed.
* NOTE: All 5 functions should be set. */
void
_gcry_set_allocation_handler (gcry_handler_alloc_t new_alloc_func,
gcry_handler_alloc_t new_alloc_secure_func,
gcry_handler_secure_check_t new_is_secure_func,
gcry_handler_realloc_t new_realloc_func,
gcry_handler_free_t new_free_func)
{
global_init ();
if (fips_mode ())
{
/* We do not want to enforce the fips mode, but merely set a
flag so that the application may check whether it is still in
fips mode. */
_gcry_inactivate_fips_mode ("custom allocation handler");
}
alloc_func = new_alloc_func;
alloc_secure_func = new_alloc_secure_func;
is_secure_func = new_is_secure_func;
realloc_func = new_realloc_func;
free_func = new_free_func;
}
/****************
* Set an optional handler which is called in case the xmalloc functions
* ran out of memory. This handler may do one of these things:
* o free some memory and return true, so that the xmalloc function
* tries again.
* o Do whatever it like and return false, so that the xmalloc functions
* use the default fatal error handler.
* o Terminate the program and don't return.
*
* The handler function is called with 3 arguments: The opaque value set with
* this function, the requested memory size, and a flag with these bits
* currently defined:
* bit 0 set = secure memory has been requested.
*/
void
_gcry_set_outofcore_handler (int (*f)(void*, size_t, unsigned int), void *value)
{
global_init ();
if (fips_mode () )
{
log_info ("out of core handler ignored in FIPS mode\n");
return;
}
outofcore_handler = f;
outofcore_handler_value = value;
}
/* Return the no_secure_memory flag. */
static int
get_no_secure_memory (void)
{
if (!no_secure_memory)
return 0;
if (_gcry_enforced_fips_mode ())
{
no_secure_memory = 0;
return 0;
}
return no_secure_memory;
}
static gcry_err_code_t
do_malloc (size_t n, unsigned int flags, void **mem)
{
gcry_err_code_t err = 0;
void *m;
if ((flags & GCRY_ALLOC_FLAG_SECURE) && !get_no_secure_memory ())
{
if (alloc_secure_func)
m = (*alloc_secure_func) (n);
else
m = _gcry_private_malloc_secure (n, !!(flags & GCRY_ALLOC_FLAG_XHINT));
}
else
{
if (alloc_func)
m = (*alloc_func) (n);
else
m = _gcry_private_malloc (n);
}
if (!m)
{
/* Make sure that ERRNO has been set in case a user supplied
memory handler didn't it correctly. */
if (!errno)
gpg_err_set_errno (ENOMEM);
err = gpg_err_code_from_errno (errno);
}
else
*mem = m;
return err;
}
void *
_gcry_malloc (size_t n)
{
void *mem = NULL;
do_malloc (n, 0, &mem);
return mem;
}
static void *
_gcry_malloc_secure_core (size_t n, int xhint)
{
void *mem = NULL;
do_malloc (n, (GCRY_ALLOC_FLAG_SECURE | (xhint? GCRY_ALLOC_FLAG_XHINT:0)),
&mem);
return mem;
}
void *
_gcry_malloc_secure (size_t n)
{
return _gcry_malloc_secure_core (n, 0);
}
int
_gcry_is_secure (const void *a)
{
if (get_no_secure_memory ())
return 0;
if (is_secure_func)
return is_secure_func (a) ;
return _gcry_private_is_secure (a);
}
void
_gcry_check_heap( const void *a )
{
(void)a;
/* FIXME: implement this*/
#if 0
if( some_handler )
some_handler(a)
else
_gcry_private_check_heap(a)
#endif
}
static void *
_gcry_realloc_core (void *a, size_t n, int xhint)
{
void *p;
/* To avoid problems with non-standard realloc implementations and
our own secmem_realloc, we divert to malloc and free here. */
if (!a)
return _gcry_malloc (n);
if (!n)
{
xfree (a);
return NULL;
}
if (realloc_func)
p = realloc_func (a, n);
else
p = _gcry_private_realloc (a, n, xhint);
if (!p && !errno)
gpg_err_set_errno (ENOMEM);
return p;
}
void *
_gcry_realloc (void *a, size_t n)
{
return _gcry_realloc_core (a, n, 0);
}
void
_gcry_free (void *p)
{
int save_errno;
if (!p)
return;
/* In case ERRNO is set we better save it so that the free machinery
may not accidentally change ERRNO. We restore it only if it was
already set to comply with the usual C semantic for ERRNO. */
save_errno = errno;
if (free_func)
free_func (p);
else
_gcry_private_free (p);
if (save_errno)
gpg_err_set_errno (save_errno);
}
void *
_gcry_calloc (size_t n, size_t m)
{
size_t bytes;
void *p;
bytes = n * m; /* size_t is unsigned so the behavior on overflow is
defined. */
if (m && bytes / m != n)
{
gpg_err_set_errno (ENOMEM);
return NULL;
}
p = _gcry_malloc (bytes);
if (p)
memset (p, 0, bytes);
return p;
}
void *
_gcry_calloc_secure (size_t n, size_t m)
{
size_t bytes;
void *p;
bytes = n * m; /* size_t is unsigned so the behavior on overflow is
defined. */
if (m && bytes / m != n)
{
gpg_err_set_errno (ENOMEM);
return NULL;
}
p = _gcry_malloc_secure (bytes);
if (p)
memset (p, 0, bytes);
return p;
}
static char *
_gcry_strdup_core (const char *string, int xhint)
{
char *string_cp = NULL;
size_t string_n = 0;
string_n = strlen (string);
if (_gcry_is_secure (string))
string_cp = _gcry_malloc_secure_core (string_n + 1, xhint);
else
string_cp = _gcry_malloc (string_n + 1);
if (string_cp)
strcpy (string_cp, string);
return string_cp;
}
/* Create and return a copy of the null-terminated string STRING. If
* it is contained in secure memory, the copy will be contained in
* secure memory as well. In an out-of-memory condition, NULL is
* returned. */
char *
_gcry_strdup (const char *string)
{
return _gcry_strdup_core (string, 0);
}
void *
_gcry_xmalloc( size_t n )
{
void *p;
while ( !(p = _gcry_malloc( n )) )
{
if ( fips_mode ()
|| !outofcore_handler
|| !outofcore_handler (outofcore_handler_value, n, 0) )
{
_gcry_fatal_error (gpg_err_code_from_errno (errno), NULL);
}
}
return p;
}
void *
_gcry_xrealloc( void *a, size_t n )
{
void *p;
while (!(p = _gcry_realloc_core (a, n, 1)))
{
if ( fips_mode ()
|| !outofcore_handler
|| !outofcore_handler (outofcore_handler_value, n,
_gcry_is_secure(a)? 3:2))
{
_gcry_fatal_error (gpg_err_code_from_errno (errno), NULL );
}
}
return p;
}
void *
_gcry_xmalloc_secure( size_t n )
{
void *p;
while (!(p = _gcry_malloc_secure_core (n, 1)))
{
if ( fips_mode ()
|| !outofcore_handler
|| !outofcore_handler (outofcore_handler_value, n, 1) )
{
_gcry_fatal_error (gpg_err_code_from_errno (errno),
_("out of core in secure memory"));
}
}
return p;
}
void *
_gcry_xcalloc( size_t n, size_t m )
{
size_t nbytes;
void *p;
nbytes = n * m;
if (m && nbytes / m != n)
{
gpg_err_set_errno (ENOMEM);
_gcry_fatal_error(gpg_err_code_from_errno (errno), NULL );
}
p = _gcry_xmalloc ( nbytes );
memset ( p, 0, nbytes );
return p;
}
void *
_gcry_xcalloc_secure( size_t n, size_t m )
{
size_t nbytes;
void *p;
nbytes = n * m;
if (m && nbytes / m != n)
{
gpg_err_set_errno (ENOMEM);
_gcry_fatal_error(gpg_err_code_from_errno (errno), NULL );
}
p = _gcry_xmalloc_secure ( nbytes );
memset ( p, 0, nbytes );
return p;
}
char *
_gcry_xstrdup (const char *string)
{
char *p;
while ( !(p = _gcry_strdup_core (string, 1)) )
{
size_t n = strlen (string);
int is_sec = !!_gcry_is_secure (string);
if (fips_mode ()
|| !outofcore_handler
|| !outofcore_handler (outofcore_handler_value, n, is_sec) )
{
_gcry_fatal_error (gpg_err_code_from_errno (errno),
is_sec? _("out of core in secure memory"):NULL);
}
}
return p;
}
/* Used before blocking system calls. */
void
_gcry_pre_syscall (void)
{
if (pre_syscall_func)
pre_syscall_func ();
}
/* Used after blocking system calls. */
void
_gcry_post_syscall (void)
{
if (post_syscall_func)
post_syscall_func ();
}
int
_gcry_get_debug_flag (unsigned int mask)
{
if ( fips_mode () )
return 0;
return (debug_flags & mask);
}
/* It is often useful to get some feedback of long running operations.
This function may be used to register a handler for this.
The callback function CB is used as:
void cb (void *opaque, const char *what, int printchar,
int current, int total);
Where WHAT is a string identifying the the type of the progress
output, PRINTCHAR the character usually printed, CURRENT the amount
of progress currently done and TOTAL the expected amount of
progress. A value of 0 for TOTAL indicates that there is no
estimation available.
Defined values for WHAT:
"need_entropy" X 0 number-of-bytes-required
When running low on entropy
"primegen" '\n' 0 0
Prime generated
'!'
Need to refresh the prime pool
'<','>'
Number of bits adjusted
'^'
Looking for a generator
'.'
Fermat tests on 10 candidates failed
':'
Restart with a new random value
'+'
Rabin Miller test passed
"pk_elg" '+','-','.','\n' 0 0
Only used in debugging mode.
"pk_dsa"
Only used in debugging mode.
*/
void
_gcry_set_progress_handler (void (*cb)(void *,const char*,int, int, int),
void *cb_data)
{
#if USE_DSA
_gcry_register_pk_dsa_progress (cb, cb_data);
#endif
#if USE_ELGAMAL
_gcry_register_pk_elg_progress (cb, cb_data);
#endif
_gcry_register_primegen_progress (cb, cb_data);
_gcry_register_random_progress (cb, cb_data);
}
/* This is a helper for the regression test suite to test Libgcrypt's locks.
It works using a one test lock with CMD controlling what to do:
30111 - Allocate and init lock
30112 - Take lock
30113 - Release lock
30114 - Destroy lock.
This function is used by tests/t-lock.c - it is not part of the
public API!
*/
static gpg_err_code_t
external_lock_test (int cmd)
{
GPGRT_LOCK_DEFINE (testlock);
gpg_err_code_t rc = 0;
switch (cmd)
{
case 30111: /* Init Lock. */
rc = gpgrt_lock_init (&testlock);
break;
case 30112: /* Take Lock. */
rc = gpgrt_lock_lock (&testlock);
break;
case 30113: /* Release Lock. */
rc = gpgrt_lock_unlock (&testlock);
break;
case 30114: /* Destroy Lock. */
rc = gpgrt_lock_destroy (&testlock);
break;
default:
rc = GPG_ERR_INV_OP;
break;
}
return rc;
}
diff --git a/src/secmem.c b/src/secmem.c
index f7ad1f66..79c135ff 100644
--- a/src/secmem.c
+++ b/src/secmem.c
@@ -1,878 +1,898 @@
/* secmem.c - memory allocation from a secure heap
* Copyright (C) 1998, 1999, 2000, 2001, 2002,
* 2003, 2007 Free Software Foundation, Inc.
* Copyright (C) 2013, 2016 g10 Code GmbH
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser general Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stdarg.h>
#include <unistd.h>
#include <stddef.h>
#if defined(HAVE_MLOCK) || defined(HAVE_MMAP)
#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#ifdef USE_CAPABILITIES
#include <sys/capability.h>
#endif
#endif
#include "g10lib.h"
#include "secmem.h"
#if defined (MAP_ANON) && ! defined (MAP_ANONYMOUS)
#define MAP_ANONYMOUS MAP_ANON
#endif
#define MINIMUM_POOL_SIZE 16384
#define STANDARD_POOL_SIZE 32768
#define DEFAULT_PAGE_SIZE 4096
typedef struct memblock
{
unsigned size; /* Size of the memory available to the
user. */
int flags; /* See below. */
PROPERLY_ALIGNED_TYPE aligned;
} memblock_t;
/* This flag specifies that the memory block is in use. */
#define MB_FLAG_ACTIVE (1 << 0)
/* An object describing a memory pool. */
typedef struct pooldesc_s
{
/* A link to the next pool. This is used to connect the overflow
* pools. */
struct pooldesc_s *next;
/* A memory buffer used as allocation pool. */
void *mem;
/* The allocated size of MEM. */
size_t size;
/* Flag indicating that this memory pool is ready for use. May be
* checked in an atexit function. */
volatile int okay;
/* Flag indicating whether MEM is mmapped. */
volatile int is_mmapped;
/* The number of allocated bytes and the number of used blocks in
* this pool. */
unsigned int cur_alloced, cur_blocks;
} pooldesc_t;
/* The pool of secure memory. This is the head of a linked list with
* the first element being the standard mlock-ed pool and the
* following elements being the overflow pools. */
static pooldesc_t mainpool;
-/* A couple of flags whith some being set early. */
+/* A couple of flags with some being set early. */
static int disable_secmem;
static int show_warning;
static int not_locked;
static int no_warning;
static int suspend_warning;
static int no_mlock;
static int no_priv_drop;
+static unsigned int auto_expand;
+
/* Lock protecting accesses to the memory pools. */
GPGRT_LOCK_DEFINE (secmem_lock);
/* Convenient macros. */
#define SECMEM_LOCK gpgrt_lock_lock (&secmem_lock)
#define SECMEM_UNLOCK gpgrt_lock_unlock (&secmem_lock)
/* The size of the memblock structure; this does not include the
memory that is available to the user. */
#define BLOCK_HEAD_SIZE \
offsetof (memblock_t, aligned)
/* Convert an address into the according memory block structure. */
#define ADDR_TO_BLOCK(addr) \
(memblock_t *) (void *) ((char *) addr - BLOCK_HEAD_SIZE)
/* Check whether P points into POOL. */
static inline int
ptr_into_pool_p (pooldesc_t *pool, const void *p)
{
/* We need to convert pointers to addresses. This is required by
C-99 6.5.8 to avoid undefined behaviour. See also
http://lists.gnupg.org/pipermail/gcrypt-devel/2007-February/001102.html
*/
uintptr_t p_addr = (uintptr_t)p;
uintptr_t pool_addr = (uintptr_t)pool->mem;
return p_addr >= pool_addr && p_addr < pool_addr + pool->size;
}
/* Update the stats. */
static void
stats_update (pooldesc_t *pool, size_t add, size_t sub)
{
if (add)
{
pool->cur_alloced += add;
pool->cur_blocks++;
}
if (sub)
{
pool->cur_alloced -= sub;
pool->cur_blocks--;
}
}
/* Return the block following MB or NULL, if MB is the last block. */
static memblock_t *
mb_get_next (pooldesc_t *pool, memblock_t *mb)
{
memblock_t *mb_next;
mb_next = (memblock_t *) (void *) ((char *) mb + BLOCK_HEAD_SIZE + mb->size);
if (! ptr_into_pool_p (pool, mb_next))
mb_next = NULL;
return mb_next;
}
/* Return the block preceding MB or NULL, if MB is the first
block. */
static memblock_t *
mb_get_prev (pooldesc_t *pool, memblock_t *mb)
{
memblock_t *mb_prev, *mb_next;
if (mb == pool->mem)
mb_prev = NULL;
else
{
mb_prev = (memblock_t *) pool->mem;
while (1)
{
mb_next = mb_get_next (pool, mb_prev);
if (mb_next == mb)
break;
else
mb_prev = mb_next;
}
}
return mb_prev;
}
/* If the preceding block of MB and/or the following block of MB
exist and are not active, merge them to form a bigger block. */
static void
mb_merge (pooldesc_t *pool, memblock_t *mb)
{
memblock_t *mb_prev, *mb_next;
mb_prev = mb_get_prev (pool, mb);
mb_next = mb_get_next (pool, mb);
if (mb_prev && (! (mb_prev->flags & MB_FLAG_ACTIVE)))
{
mb_prev->size += BLOCK_HEAD_SIZE + mb->size;
mb = mb_prev;
}
if (mb_next && (! (mb_next->flags & MB_FLAG_ACTIVE)))
mb->size += BLOCK_HEAD_SIZE + mb_next->size;
}
/* Return a new block, which can hold SIZE bytes. */
static memblock_t *
mb_get_new (pooldesc_t *pool, memblock_t *block, size_t size)
{
memblock_t *mb, *mb_split;
for (mb = block; ptr_into_pool_p (pool, mb); mb = mb_get_next (pool, mb))
if (! (mb->flags & MB_FLAG_ACTIVE) && mb->size >= size)
{
/* Found a free block. */
mb->flags |= MB_FLAG_ACTIVE;
if (mb->size - size > BLOCK_HEAD_SIZE)
{
/* Split block. */
mb_split = (memblock_t *) (void *) (((char *) mb) + BLOCK_HEAD_SIZE
+ size);
mb_split->size = mb->size - size - BLOCK_HEAD_SIZE;
mb_split->flags = 0;
mb->size = size;
mb_merge (pool, mb_split);
}
break;
}
if (! ptr_into_pool_p (pool, mb))
{
gpg_err_set_errno (ENOMEM);
mb = NULL;
}
return mb;
}
/* Print a warning message. */
static void
print_warn (void)
{
if (!no_warning)
log_info (_("Warning: using insecure memory!\n"));
}
/* Lock the memory pages of pool P of size N into core and drop
* privileges. */
static void
lock_pool_pages (void *p, size_t n)
{
#if defined(USE_CAPABILITIES) && defined(HAVE_MLOCK)
int err;
{
cap_t cap;
if (!no_priv_drop)
{
cap = cap_from_text ("cap_ipc_lock+ep");
cap_set_proc (cap);
cap_free (cap);
}
err = no_mlock? 0 : mlock (p, n);
if (err && errno)
err = errno;
if (!no_priv_drop)
{
cap = cap_from_text ("cap_ipc_lock+p");
cap_set_proc (cap);
cap_free(cap);
}
}
if (err)
{
if (err != EPERM
#ifdef EAGAIN /* BSD and also Linux may return EAGAIN */
&& err != EAGAIN
#endif
#ifdef ENOSYS /* Some SCOs return this (function not implemented) */
&& err != ENOSYS
#endif
#ifdef ENOMEM /* Linux might return this. */
&& err != ENOMEM
#endif
)
log_error ("can't lock memory: %s\n", strerror (err));
show_warning = 1;
not_locked = 1;
}
#elif defined(HAVE_MLOCK)
uid_t uid;
int err;
uid = getuid ();
#ifdef HAVE_BROKEN_MLOCK
/* Under HP/UX mlock segfaults if called by non-root. Note, we have
noch checked whether mlock does really work under AIX where we
also detected a broken nlock. Note further, that using plock ()
is not a good idea under AIX. */
if (uid)
{
errno = EPERM;
err = errno;
}
else
{
err = no_mlock? 0 : mlock (p, n);
if (err && errno)
err = errno;
}
#else /* !HAVE_BROKEN_MLOCK */
err = no_mlock? 0 : mlock (p, n);
if (err && errno)
err = errno;
#endif /* !HAVE_BROKEN_MLOCK */
/* Test whether we are running setuid(0). */
if (uid && ! geteuid ())
{
/* Yes, we are. */
if (!no_priv_drop)
{
/* Check that we really dropped the privs.
* Note: setuid(0) should always fail */
if (setuid (uid) || getuid () != geteuid () || !setuid (0))
log_fatal ("failed to reset uid: %s\n", strerror (errno));
}
}
if (err)
{
if (err != EPERM
#ifdef EAGAIN /* BSD and also Linux may return this. */
&& err != EAGAIN
#endif
#ifdef ENOSYS /* Some SCOs return this (function not implemented). */
&& err != ENOSYS
#endif
#ifdef ENOMEM /* Linux might return this. */
&& err != ENOMEM
#endif
)
log_error ("can't lock memory: %s\n", strerror (err));
show_warning = 1;
not_locked = 1;
}
#elif defined ( __QNX__ )
/* QNX does not page at all, so the whole secure memory stuff does
* not make much sense. However it is still of use because it
* wipes out the memory on a free().
* Therefore it is sufficient to suppress the warning. */
(void)p;
(void)n;
#elif defined (HAVE_DOSISH_SYSTEM) || defined (__CYGWIN__)
/* It does not make sense to print such a warning, given the fact that
* this whole Windows !@#$% and their user base are inherently insecure. */
(void)p;
(void)n;
#elif defined (__riscos__)
/* No virtual memory on RISC OS, so no pages are swapped to disc,
* besides we don't have mmap, so we don't use it! ;-)
* But don't complain, as explained above. */
(void)p;
(void)n;
#else
(void)p;
(void)n;
if (!no_mlock)
log_info ("Please note that you don't have secure memory on this system\n");
#endif
}
/* Initialize POOL. */
static void
init_pool (pooldesc_t *pool, size_t n)
{
memblock_t *mb;
pool->size = n;
if (disable_secmem)
log_bug ("secure memory is disabled");
#if HAVE_MMAP
{
size_t pgsize;
long int pgsize_val;
# if defined(HAVE_SYSCONF) && defined(_SC_PAGESIZE)
pgsize_val = sysconf (_SC_PAGESIZE);
# elif defined(HAVE_GETPAGESIZE)
pgsize_val = getpagesize ();
# else
pgsize_val = -1;
# endif
pgsize = (pgsize_val > 0)? pgsize_val:DEFAULT_PAGE_SIZE;
pool->size = (pool->size + pgsize - 1) & ~(pgsize - 1);
# ifdef MAP_ANONYMOUS
pool->mem = mmap (0, pool->size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
# else /* map /dev/zero instead */
{
int fd;
fd = open ("/dev/zero", O_RDWR);
if (fd == -1)
{
log_error ("can't open /dev/zero: %s\n", strerror (errno));
pool->mem = (void *) -1;
}
else
{
pool->mem = mmap (0, pool->size,
(PROT_READ | PROT_WRITE), MAP_PRIVATE, fd, 0);
close (fd);
}
}
# endif
if (pool->mem == (void *) -1)
log_info ("can't mmap pool of %u bytes: %s - using malloc\n",
(unsigned) pool->size, strerror (errno));
else
{
pool->is_mmapped = 1;
pool->okay = 1;
}
}
#endif /*HAVE_MMAP*/
if (!pool->okay)
{
pool->mem = malloc (pool->size);
if (!pool->mem)
log_fatal ("can't allocate memory pool of %u bytes\n",
(unsigned) pool->size);
else
pool->okay = 1;
}
/* Initialize first memory block. */
mb = (memblock_t *) pool->mem;
mb->size = pool->size - BLOCK_HEAD_SIZE;
mb->flags = 0;
}
+
+/* Enable overflow pool allocation in all cases. CHUNKSIZE is a hint
+ * on how large to allocate overflow pools. */
+void
+_gcry_secmem_set_auto_expand (unsigned int chunksize)
+{
+ /* Round up to a multiple of the STANDARD_POOL_SIZE. */
+ chunksize = ((chunksize + (2*STANDARD_POOL_SIZE) - 1)
+ / STANDARD_POOL_SIZE ) * STANDARD_POOL_SIZE;
+ if (chunksize < STANDARD_POOL_SIZE) /* In case of overflow. */
+ chunksize = STANDARD_POOL_SIZE;
+
+ SECMEM_LOCK;
+ auto_expand = chunksize;
+ SECMEM_UNLOCK;
+}
+
+
void
_gcry_secmem_set_flags (unsigned flags)
{
int was_susp;
SECMEM_LOCK;
was_susp = suspend_warning;
no_warning = flags & GCRY_SECMEM_FLAG_NO_WARNING;
suspend_warning = flags & GCRY_SECMEM_FLAG_SUSPEND_WARNING;
no_mlock = flags & GCRY_SECMEM_FLAG_NO_MLOCK;
no_priv_drop = flags & GCRY_SECMEM_FLAG_NO_PRIV_DROP;
/* and now issue the warning if it is not longer suspended */
if (was_susp && !suspend_warning && show_warning)
{
show_warning = 0;
print_warn ();
}
SECMEM_UNLOCK;
}
unsigned int
_gcry_secmem_get_flags (void)
{
unsigned flags;
SECMEM_LOCK;
flags = no_warning ? GCRY_SECMEM_FLAG_NO_WARNING : 0;
flags |= suspend_warning ? GCRY_SECMEM_FLAG_SUSPEND_WARNING : 0;
flags |= not_locked ? GCRY_SECMEM_FLAG_NOT_LOCKED : 0;
flags |= no_mlock ? GCRY_SECMEM_FLAG_NO_MLOCK : 0;
flags |= no_priv_drop ? GCRY_SECMEM_FLAG_NO_PRIV_DROP : 0;
SECMEM_UNLOCK;
return flags;
}
/* This function initializes the main memory pool MAINPOOL. Itis
* expected to be called with the secmem lock held. */
static void
_gcry_secmem_init_internal (size_t n)
{
pooldesc_t *pool;
pool = &mainpool;
if (!n)
{
#ifdef USE_CAPABILITIES
/* drop all capabilities */
if (!no_priv_drop)
{
cap_t cap;
cap = cap_from_text ("all-eip");
cap_set_proc (cap);
cap_free (cap);
}
#elif !defined(HAVE_DOSISH_SYSTEM)
uid_t uid;
disable_secmem = 1;
uid = getuid ();
if (uid != geteuid ())
{
if (setuid (uid) || getuid () != geteuid () || !setuid (0))
log_fatal ("failed to drop setuid\n");
}
#endif
}
else
{
if (n < MINIMUM_POOL_SIZE)
n = MINIMUM_POOL_SIZE;
if (! pool->okay)
{
init_pool (pool, n);
lock_pool_pages (pool->mem, n);
}
else
log_error ("Oops, secure memory pool already initialized\n");
}
}
/* Initialize the secure memory system. If running with the necessary
privileges, the secure memory pool will be locked into the core in
order to prevent page-outs of the data. Furthermore allocated
secure memory will be wiped out when released. */
void
_gcry_secmem_init (size_t n)
{
SECMEM_LOCK;
_gcry_secmem_init_internal (n);
SECMEM_UNLOCK;
}
gcry_err_code_t
_gcry_secmem_module_init ()
{
/* Not anymore needed. */
return 0;
}
static void *
_gcry_secmem_malloc_internal (size_t size, int xhint)
{
pooldesc_t *pool;
memblock_t *mb;
pool = &mainpool;
if (!pool->okay)
{
/* Try to initialize the pool if the user forgot about it. */
_gcry_secmem_init_internal (STANDARD_POOL_SIZE);
if (!pool->okay)
{
log_info (_("operation is not possible without "
"initialized secure memory\n"));
gpg_err_set_errno (ENOMEM);
return NULL;
}
}
if (not_locked && fips_mode ())
{
log_info (_("secure memory pool is not locked while in FIPS mode\n"));
gpg_err_set_errno (ENOMEM);
return NULL;
}
if (show_warning && !suspend_warning)
{
show_warning = 0;
print_warn ();
}
/* Blocks are always a multiple of 32. */
size = ((size + 31) / 32) * 32;
mb = mb_get_new (pool, (memblock_t *) pool->mem, size);
if (mb)
{
stats_update (pool, mb->size, 0);
return &mb->aligned.c;
}
/* If we are called from xmalloc style function resort to the
* overflow pools to return memory. We don't do this in FIPS mode,
* though. */
- if (xhint && !fips_mode ())
+ if ((xhint || auto_expand) && !fips_mode ())
{
for (pool = pool->next; pool; pool = pool->next)
{
mb = mb_get_new (pool, (memblock_t *) pool->mem, size);
if (mb)
{
stats_update (pool, mb->size, 0);
return &mb->aligned.c;
}
}
/* Allocate a new overflow pool. We put a new pool right after
* the mainpool so that the next allocation will happen in that
* pool and not in one of the older pools. When this new pool
* gets full we will try to find space in the older pools. */
pool = calloc (1, sizeof *pool);
if (!pool)
return NULL; /* Not enough memory for a new pool descriptor. */
- pool->size = STANDARD_POOL_SIZE;
+ pool->size = auto_expand? auto_expand : STANDARD_POOL_SIZE;
pool->mem = malloc (pool->size);
if (!pool->mem)
return NULL; /* Not enough memory available for a new pool. */
/* Initialize first memory block. */
mb = (memblock_t *) pool->mem;
mb->size = pool->size - BLOCK_HEAD_SIZE;
mb->flags = 0;
pool->okay = 1;
/* Take care: in _gcry_private_is_secure we do not lock and thus
* we assume that the second assignment below is atomic. */
pool->next = mainpool.next;
mainpool.next = pool;
/* After the first time we allocated an overflow pool, print a
* warning. */
if (!pool->next)
print_warn ();
/* Allocate. */
mb = mb_get_new (pool, (memblock_t *) pool->mem, size);
if (mb)
{
stats_update (pool, mb->size, 0);
return &mb->aligned.c;
}
}
return NULL;
}
/* Allocate a block from the secmem of SIZE. With XHINT set assume
* that the caller is a xmalloc style function. */
void *
_gcry_secmem_malloc (size_t size, int xhint)
{
void *p;
SECMEM_LOCK;
p = _gcry_secmem_malloc_internal (size, xhint);
SECMEM_UNLOCK;
return p;
}
static int
_gcry_secmem_free_internal (void *a)
{
pooldesc_t *pool;
memblock_t *mb;
int size;
for (pool = &mainpool; pool; pool = pool->next)
if (pool->okay && ptr_into_pool_p (pool, a))
break;
if (!pool)
return 0; /* A does not belong to use. */
mb = ADDR_TO_BLOCK (a);
size = mb->size;
/* This does not make much sense: probably this memory is held in the
* cache. We do it anyway: */
#define MB_WIPE_OUT(byte) \
wipememory2 (((char *) mb + BLOCK_HEAD_SIZE), (byte), size);
MB_WIPE_OUT (0xff);
MB_WIPE_OUT (0xaa);
MB_WIPE_OUT (0x55);
MB_WIPE_OUT (0x00);
/* Update stats. */
stats_update (pool, 0, size);
mb->flags &= ~MB_FLAG_ACTIVE;
mb_merge (pool, mb);
return 1; /* Freed. */
}
/* Wipe out and release memory. Returns true if this function
* actually released A. */
int
_gcry_secmem_free (void *a)
{
int mine;
if (!a)
return 1; /* Tell caller that we handled it. */
SECMEM_LOCK;
mine = _gcry_secmem_free_internal (a);
SECMEM_UNLOCK;
return mine;
}
static void *
_gcry_secmem_realloc_internal (void *p, size_t newsize, int xhint)
{
memblock_t *mb;
size_t size;
void *a;
mb = (memblock_t *) (void *) ((char *) p
- ((size_t) &((memblock_t *) 0)->aligned.c));
size = mb->size;
if (newsize < size)
{
/* It is easier to not shrink the memory. */
a = p;
}
else
{
a = _gcry_secmem_malloc_internal (newsize, xhint);
if (a)
{
memcpy (a, p, size);
memset ((char *) a + size, 0, newsize - size);
_gcry_secmem_free_internal (p);
}
}
return a;
}
/* Realloc memory. With XHINT set assume that the caller is a xmalloc
* style function. */
void *
_gcry_secmem_realloc (void *p, size_t newsize, int xhint)
{
void *a;
SECMEM_LOCK;
a = _gcry_secmem_realloc_internal (p, newsize, xhint);
SECMEM_UNLOCK;
return a;
}
/* Return true if P points into the secure memory areas. */
int
_gcry_private_is_secure (const void *p)
{
pooldesc_t *pool;
/* We do no lock here because once a pool is allocatred it will not
* be removed anymore (except for gcry_secmem_term). Further,
* adding a new pool to the list should be atomic. */
for (pool = &mainpool; pool; pool = pool->next)
if (pool->okay && ptr_into_pool_p (pool, p))
return 1;
return 0;
}
/****************
* Warning: This code might be called by an interrupt handler
* and frankly, there should really be such a handler,
* to make sure that the memory is wiped out.
* We hope that the OS wipes out mlocked memory after
* receiving a SIGKILL - it really should do so, otherwise
* there is no chance to get the secure memory cleaned.
*/
void
_gcry_secmem_term ()
{
pooldesc_t *pool, *next;
for (pool = &mainpool; pool; pool = next)
{
next = pool->next;
if (!pool->okay)
continue;
wipememory2 (pool->mem, 0xff, pool->size);
wipememory2 (pool->mem, 0xaa, pool->size);
wipememory2 (pool->mem, 0x55, pool->size);
wipememory2 (pool->mem, 0x00, pool->size);
if (0)
;
#if HAVE_MMAP
else if (pool->is_mmapped)
munmap (pool->mem, pool->size);
#endif
else
free (pool->mem);
pool->mem = NULL;
pool->okay = 0;
pool->size = 0;
if (pool != &mainpool)
free (pool);
}
mainpool.next = NULL;
not_locked = 0;
}
/* Print stats of the secmem allocator. With EXTENDED passwed as true
* a detiled listing is returned (used for testing). */
void
_gcry_secmem_dump_stats (int extended)
{
pooldesc_t *pool;
memblock_t *mb;
int i, poolno;
SECMEM_LOCK;
for (pool = &mainpool, poolno = 0; pool; pool = pool->next, poolno++)
{
if (!extended)
{
if (pool->okay)
log_info ("%-13s %u/%lu bytes in %u blocks\n",
pool == &mainpool? "secmem usage:":"",
pool->cur_alloced, (unsigned long)pool->size,
pool->cur_blocks);
}
else
{
for (i = 0, mb = (memblock_t *) pool->mem;
ptr_into_pool_p (pool, mb);
mb = mb_get_next (pool, mb), i++)
log_info ("SECMEM: pool %d %s block %i size %i\n",
poolno,
(mb->flags & MB_FLAG_ACTIVE) ? "used" : "free",
i,
mb->size);
}
}
SECMEM_UNLOCK;
}
diff --git a/src/secmem.h b/src/secmem.h
index 29dd64fc..8ad6ef1a 100644
--- a/src/secmem.h
+++ b/src/secmem.h
@@ -1,41 +1,42 @@
/* secmem.h - internal definitions for secmem
* Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser general Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#ifndef G10_SECMEM_H
#define G10_SECMEM_H 1
void _gcry_secmem_init (size_t npool);
void _gcry_secmem_term (void);
void *_gcry_secmem_malloc (size_t size, int xhint) _GCRY_GCC_ATTR_MALLOC;
void *_gcry_secmem_realloc (void *a, size_t newsize, int xhint);
int _gcry_secmem_free (void *a);
void _gcry_secmem_dump_stats (int extended);
+void _gcry_secmem_set_auto_expand (unsigned int chunksize);
void _gcry_secmem_set_flags (unsigned flags);
unsigned _gcry_secmem_get_flags(void);
int _gcry_private_is_secure (const void *p);
/* Flags for _gcry_secmem_{set,get}_flags. */
#define GCRY_SECMEM_FLAG_NO_WARNING (1 << 0)
#define GCRY_SECMEM_FLAG_SUSPEND_WARNING (1 << 1)
#define GCRY_SECMEM_FLAG_NOT_LOCKED (1 << 2)
#define GCRY_SECMEM_FLAG_NO_MLOCK (1 << 3)
#define GCRY_SECMEM_FLAG_NO_PRIV_DROP (1 << 4)
#endif /* G10_SECMEM_H */

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