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	diff --git a/doc/gcrypt.texi b/doc/gcrypt.texi
	index b7817d92..3bd26862 100644
	--- a/doc/gcrypt.texi
	+++ b/doc/gcrypt.texi
	@@ -1,5171 +1,5182 @@
	\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.

	Copyright @copyright{} 2000, 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2011 Free Software Foundation, Inc.

	@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 and 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
	* 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 common error handling related code for 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.
	@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 compilers
	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.
	@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, with the exception of the @code{GCRYCTL_SET_THREAD_CBS} command
	(called via the @code{gcry_control} function).
	@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 intialized. */
	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 intialized. */
	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 intialized. */

	/* Allocate a pool of 16k secure memory. This make the secure memory
	available and also drops privileges where needed. */
	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 your application is multi-threaded, you must set the thread support
	callbacks with the @code{GCRYCTL_SET_THREAD_CBS} command
	@strong{before} any other function in the library.

	This is easy enough if you are indeed writing an application using
	Libgcrypt. It is rather problematic if you are writing a library
	instead. Here are some tips what to do if you are writing a library:

	If your library requires a certain thread package, just initialize
	Libgcrypt to use this thread package. If your library supports multiple
	thread packages, but needs to be configured, you will have to
	implement a way to determine which thread package the application
	wants to use with your library anyway. Then configure Libgcrypt to use
	this thread package.

	If your library is fully reentrant without any special support by a
	thread package, then you are lucky indeed. Unfortunately, this does
	not relieve you from doing either of the two above, or use a third
	option. The third option is to let the application initialize Libgcrypt
	for you. Then you are not using Libgcrypt transparently, though.

	As if this was not difficult enough, a conflict may arise if two
	libraries try to initialize Libgcrypt independently of each others, and
	both such libraries are then linked into the same application. To
	make it a bit simpler for you, this will probably work, but only if
	both libraries have the same requirement for the thread package. This
	is currently only supported for the non-threaded case, GNU Pth and
	pthread.

	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.

	Note that future versions of Libgcrypt will drop this flexible thread
	support and instead only support the platforms standard thread
	implementation.


	@item
	The function @code{gcry_check_version} must be called before any other
	function in the library, except the @code{GCRYCTL_SET_THREAD_CBS}
	command (called via the @code{gcry_control} function), because it
	initializes the thread support subsystem in Libgcrypt. 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


	Libgcrypt contains convenient macros, which define the
	necessary thread callbacks for PThread and for GNU Pth:

	@table @code
	@item GCRY_THREAD_OPTION_PTH_IMPL

	This macro defines the following (static) symbols:
	@code{gcry_pth_init}, @code{gcry_pth_mutex_init},
	@code{gcry_pth_mutex_destroy}, @code{gcry_pth_mutex_lock},
	@code{gcry_pth_mutex_unlock}, @code{gcry_pth_read},
	@code{gcry_pth_write}, @code{gcry_pth_select},
	@code{gcry_pth_waitpid}, @code{gcry_pth_accept},
	@code{gcry_pth_connect}, @code{gcry_threads_pth}.

	After including this macro, @code{gcry_control()} shall be used with a
	command of @code{GCRYCTL_SET_THREAD_CBS} in order to register the
	thread callback structure named ``gcry_threads_pth''. Example:

	@smallexample
	ret = gcry_control (GCRYCTL_SET_THREAD_CBS, &gcry_threads_pth);
	@end smallexample


	@item GCRY_THREAD_OPTION_PTHREAD_IMPL

	This macro defines the following (static) symbols:
	@code{gcry_pthread_mutex_init}, @code{gcry_pthread_mutex_destroy},
	@code{gcry_pthread_mutex_lock}, @code{gcry_pthread_mutex_unlock},
	@code{gcry_threads_pthread}.

	After including this macro, @code{gcry_control()} shall be used with a
	command of @code{GCRYCTL_SET_THREAD_CBS} in order to register the
	thread callback structure named ``gcry_threads_pthread''. Example:

	@smallexample
	ret = gcry_control (GCRYCTL_SET_THREAD_CBS, &gcry_threads_pthread);
	@end smallexample


	@end table

	Note that these macros need to be terminated with a semicolon. Keep
	in mind that these are convenient macros for C programmers; C++
	programmers might have to wrap these macros in an ``extern C'' body.


	@node Enabling FIPS mode
	@section How to enable the FIPS mode
	@cindex FIPS mode
	@cindex FIPS 140

	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}. The Enforced FIPS mode helps to
	-detect applications which don't fulfill all requirements for using
	+@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.



	@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 recommened. However,
	for some applications the extra quality random Libgcrypt tries to create
	is not justified and this option may help to get better performace.
	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 randum number generator related statistics to the
	library's logging stream.

	@item GCRYCTL_DUMP_MEMORY_STATS; Arguments: none
	This command dumps memory managment related statistics to the library's
	logging stream.

	@item GCRYCTL_DUMP_SECMEM_STATS; Arguments: none
	This command dumps secure memory manamgent 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 priviliges
	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_INIT_SECMEM; Arguments: 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_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
	inital 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_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 intialization is by calling gcry_check_version.

	@item GCRYCTL_INITIALIZATION_FINISHED; Arguments: none
	This command tells the library that the application has finished the
	intialization.

	@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 registers a thread-callback structure.
	@xref{Multi-Threading}.

	@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 intialization has
	-been finished but not before a gcry_version_check.
	+been finished but not before a @code{gcry_check_version}.

	@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 intialization has been finished but not before a gcry_version_check.
	+the intialization 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 intialization has been finished but not
	-before a gcry_version_check. An application may use this command or
	+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 gcry_check_version and that is actually the recommended way to let an
	+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 intialization.

	+@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 intialization.
	+
	@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
	performace tests it is sometimes required not to use such a feature.
	This option may be used to disabale a certain feature; i.e. Libgcrypt
	behaves as if this feature has not been detected. 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}.

	@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 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. The constant is provided but there is
	currently no implementation for it because the algorithm is patented.

	@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. Note, that we currently
	only support the 40 bit variant. The identifier for 128 is reserved for
	future use.

	@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}.

	@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
	@cindex CFB, Cipher Feedback mode
	Cipher Feedback mode. The shift size equals the block size of the
	cipher (e.g. for AES it is CFB-128).

	@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.

	@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. Any
	block cipher mode (@code{GCRY_CIPHER_MODE_ECB},
	@code{GCRY_CIPHER_MODE_CBC}, @code{GCRY_CIPHER_MODE_CFB},
	@code{GCRY_CIPHER_MODE_OFB} or @code{GCRY_CIPHER_MODE_CTR}) will work
	with any block cipher algorithm.

	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.
	@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

	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} or
	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.

	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.

	The function returns @code{0} on success or an error code.
	@end deftypefun


	OpenPGP (as defined in RFC-2440) 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.

	Currently no information is available.
	@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 blocklength 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 @asis
	@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

	@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 = dP}.
	@item d-mpi
	The private key @math{d}
	@end table

	All point values are encoded in standard format; Libgcrypt does
	currently only support uncompressed points, thus the first byte needs to
	be @code{0x04}.

	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

	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
	Note that we will in future allow to use keys without p,q and u
	specified and may also support other parameters for performance
	reasons.

	@noindent

	Some functions operating on S-expressions support `flags', that
	influence the operation. These flags have to be listed in a
	sub-S-expression named `flags'; the following flags are known:

	@table @code
	@item pkcs1
	Use PKCS#1 block type 2 padding for encryption, block type 1 padding
	for signing.
	@item oaep
	Use RSA-OAEP padding for encryption.
	@item pss
	Use RSA-PSS padding for signing.
	@item 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.
	@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
	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".
	@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)}.

	@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.

	@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
	This is only used with RSA to give a hint for the public exponent. The
	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
	This is only meanigful for DSA keys. If it is given the DSA key is
	generated with a Q parameyer of this size. 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 transient-key
	This is only meaningful for RSA, DSA, ECDSA, and ECDH keys. This is a flag
	with no value. 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 domain
	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
	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 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 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
	Force the use of the FIPS 186-2 key generation algorithm instead of
	the default algorithm. This algorithm is slighlty 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
	@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
	As an example, here is what the Elgamal key generation returns:

	@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

	@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

	@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 MAC 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 RIPE-MD-160
	@cindex MD2, MD4, MD5
	@cindex TIGER, TIGER1, TIGER2
	@cindex HAVAL
	@cindex Whirlpool
	@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 algorithms ha 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_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.

	@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. 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}.

	@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, set the MAC key to the value of
	@var{key} of length @var{keylen} bytes. There is no restriction on
	the length of the key.
	@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.
	@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} does this implicitly. After this has been
	done no further updates (by means of @code{gcry_md_write} or
	@code{gcry_md_putc} are allowed. 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 reseted (using @code{gcry_md_close} or
	@code{gcry_md_reset}. @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

	Because it is often necessary to get the message digest of one block of
	memory, a fast convenience function is available for this task:

	@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 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 create 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 ***************** 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.

	@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 called the "type" and should always exist and 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 {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


	@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.
	* 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

	@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}.
	@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 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

	@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}. 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.

	@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.

	@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 C style string with each byte of the MPI encoded as 2 hex
	digits. 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}.
	@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} should be negative or 0.
	@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


	@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 Miscellaneous
	@section Miscellaneous

	@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}).

	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 {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

	@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}. Currently only the flag
	@code{GCRYMPI_FLAG_SECURE} is allowed to convert @var{a} into an MPI
	stored in "secure memory".
	@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}. Note that
	this function is currently useless as no flags are allowed.
	@end deftypefun

	@deftypefun int gcry_mpi_get_flag (@w{gcry_mpi_t @var{a}}, @w{enum gcry_mpi_flag @var{flag}})

	Return true when the @var{flag} is set for @var{a}.
	@end deftypefun

	@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 value 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 wether 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.
	@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

	@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 *************** 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 shemes
	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.

	@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 only supported hardware RNG is
	the Padlock engine of VIA (Centaur) CPUs. It is not available in FIPS
	mode.

	@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 RIPE-MD160 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 implementaion 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/radnom} 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 stucked 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 fature 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 orginal random value. The encrtypted result is then
	decrypted and checked that it macthes 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 contidion 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
	introducted 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 runing 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 intialization function @code{gcry_check_version}.

	@item 3
	Init to Self-Test is either triggred by a dedicated API call or implicit
	by invoking a libgrypt service conrolled by the FSM.

	@item 4
	Self-Test to Operational is triggered after all self-tests passed
	successfully.

	@item 5
	Operational to Shutdown is an artifical 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 triggred 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 artifical state to document that Libgcrypt
	has not ye been initializaed but the process is about to terminate.

	@item 12
	Power-On to Fatal-Error will be triggerd if certain Libgcrypt functions
	are used without having reached the Init state.

	@item 13
	Self-Test to Fatal-Error is triggred by severe errors in Libgcrypt while
	running self-tests.

	@item 14
	Self-Test to Error is triggred 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 triggred 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 damon 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/fips.c b/src/fips.c
	index a3445eb2..e45baba6 100644
	--- a/src/fips.c
	+++ b/src/fips.c
	@@ -1,852 +1,860 @@
	/* fips.c - FIPS mode management
	* Copyright (C) 2008 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, see <http://www.gnu.org/licenses/>.
	*/

	#include <config.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <errno.h>
	#include <unistd.h>
	#include <string.h>
	#ifdef ENABLE_HMAC_BINARY_CHECK
	# include <dlfcn.h>
	#endif
	#ifdef HAVE_SYSLOG
	# include <syslog.h>
	#endif /HAVE_SYSLOG/

	#include "g10lib.h"
	#include "ath.h"
	#include "cipher-proto.h"
	#include "hmac256.h"


	/* The name of the file used to foce libgcrypt into fips mode. */
	#define FIPS_FORCE_FILE "/etc/gcrypt/fips_enabled"


	/* The states of the finite state machine used in fips mode. */
	enum module_states
	{
	/* POWEROFF cannot be represented. */
	STATE_POWERON = 0,
	STATE_INIT,
	STATE_SELFTEST,
	STATE_OPERATIONAL,
	STATE_ERROR,
	STATE_FATALERROR,
	STATE_SHUTDOWN
	};


	/* Flag telling whether we are in fips mode. It uses inverse logic so
	that fips mode is the default unless changed by the initialization
	code. To check whether fips mode is enabled, use the function
	fips_mode()! */
	static int no_fips_mode_required;

	/* Flag to indicate that we are in the enforced FIPS mode. */
	static int enforced_fips_mode;

	/* If this flag is set, the application may no longer assume that the
	process is running in FIPS mode. This flag is protected by the
	FSM_LOCK. */
	static int inactive_fips_mode;

	/* This is the lock we use to protect the FSM. */
	static ath_mutex_t fsm_lock;

	/* The current state of the FSM. The whole state machinery is only
	used while in fips mode. Change this only while holding fsm_lock. */
	static enum module_states current_state;





	static void fips_new_state (enum module_states new_state);



	/* Convert lowercase hex digits; assumes valid hex digits. */
	#define loxtoi_1(p) ((p) <= '9'? ((p)- '0'): (*(p)-'a'+10))
	#define loxtoi_2(p) ((loxtoi_1(p) * 16) + loxtoi_1((p)+1))

	/* Returns true if P points to a lowercase hex digit. */
	#define loxdigit_p(p) !!strchr ("01234567890abcdef", *(p))



	/* Check whether the OS is in FIPS mode and record that in a module
	local variable. If FORCE is passed as true, fips mode will be
	enabled anyway. Note: This function is not thread-safe and should
	be called before any threads are created. This function may only
	be called once. */
	void
	_gcry_initialize_fips_mode (int force)
	{
	static int done;
	gpg_error_t err;

	/* Make sure we are not accidently called twice. */
	if (done)
	{
	if ( fips_mode () )
	{
	fips_new_state (STATE_FATALERROR);
	fips_noreturn ();
	}
	/* If not in fips mode an assert is sufficient. */
	gcry_assert (!done);
	}
	done = 1;

	/* If the calling application explicitly requested fipsmode, do so. */
	if (force)
	{
	gcry_assert (!no_fips_mode_required);
	goto leave;
	}

	/* For testing the system it is useful to override the system
	provided detection of the FIPS mode and force FIPS mode using a
	file. The filename is hardwired so that there won't be any
	confusion on whether /etc/gcrypt/ or /usr/local/etc/gcrypt/ is
	actually used. The file itself may be empty. */
	if ( !access (FIPS_FORCE_FILE, F_OK) )
	{
	gcry_assert (!no_fips_mode_required);
	goto leave;
	}

	/* Checking based on /proc file properties. */
	{
	static const char procfname[] = "/proc/sys/crypto/fips_enabled";
	FILE *fp;
	int saved_errno;

	fp = fopen (procfname, "r");
	if (fp)
	{
	char line[256];

	if (fgets (line, sizeof line, fp) && atoi (line))
	{
	/* System is in fips mode. */
	fclose (fp);
	gcry_assert (!no_fips_mode_required);
	goto leave;
	}
	fclose (fp);
	}
	else if ((saved_errno = errno) != ENOENT
	&& saved_errno != EACCES
	&& !access ("/proc/version", F_OK) )
	{
	/* Problem reading the fips file despite that we have the proc
	file system. We better stop right away. */
	log_info ("FATAL: error reading `%s' in libgcrypt: %s\n",
	procfname, strerror (saved_errno));
	#ifdef HAVE_SYSLOG
	syslog (LOG_USER\|LOG_ERR, "Libgcrypt error: "
	"reading `%s' failed: %s - abort",
	procfname, strerror (saved_errno));
	#endif /HAVE_SYSLOG/
	abort ();
	}
	}

	/* Fips not not requested, set flag. */
	no_fips_mode_required = 1;

	leave:
	if (!no_fips_mode_required)
	{
	/* Yes, we are in FIPS mode. */
	FILE *fp;

	/* Intitialize the lock to protect the FSM. */
	err = ath_mutex_init (&fsm_lock);
	if (err)
	{
	/* If that fails we can't do anything but abort the
	process. We need to use log_info so that the FSM won't
	get involved. */
	log_info ("FATAL: failed to create the FSM lock in libgcrypt: %s\n",
	strerror (err));
	#ifdef HAVE_SYSLOG
	syslog (LOG_USER\|LOG_ERR, "Libgcrypt error: "
	"creating FSM lock failed: %s - abort",
	strerror (err));
	#endif /HAVE_SYSLOG/
	abort ();
	}


	/* If the FIPS force files exists, is readable and has a number
	!= 0 on its first line, we enable the enforced fips mode. */
	fp = fopen (FIPS_FORCE_FILE, "r");
	if (fp)
	{
	char line[256];

	if (fgets (line, sizeof line, fp) && atoi (line))
	enforced_fips_mode = 1;
	fclose (fp);
	}

	/* Now get us into the INIT state. */
	fips_new_state (STATE_INIT);

	}
	return;
	}

	static void
	lock_fsm (void)
	{
	gpg_error_t err;

	err = ath_mutex_lock (&fsm_lock);
	if (err)
	{
	log_info ("FATAL: failed to acquire the FSM lock in libgrypt: %s\n",
	strerror (err));
	#ifdef HAVE_SYSLOG
	syslog (LOG_USER\|LOG_ERR, "Libgcrypt error: "
	"acquiring FSM lock failed: %s - abort",
	strerror (err));
	#endif /HAVE_SYSLOG/
	abort ();
	}
	}

	static void
	unlock_fsm (void)
	{
	gpg_error_t err;

	err = ath_mutex_unlock (&fsm_lock);
	if (err)
	{
	log_info ("FATAL: failed to release the FSM lock in libgrypt: %s\n",
	strerror (err));
	#ifdef HAVE_SYSLOG
	syslog (LOG_USER\|LOG_ERR, "Libgcrypt error: "
	"releasing FSM lock failed: %s - abort",
	strerror (err));
	#endif /HAVE_SYSLOG/
	abort ();
	}
	}


	/* This function returns true if fips mode is enabled. This is
	independent of the fips required finite state machine and only used
	to enable fips specific code. Please use the fips_mode macro
	instead of calling this function directly. */
	int
	_gcry_fips_mode (void)
	{
	/* No locking is required because we have the requirement that this
	variable is only initialized once with no other threads
	existing. */
	return !no_fips_mode_required;
	}


	/* Return a flag telling whether we are in the enforced fips mode. */
	int
	_gcry_enforced_fips_mode (void)
	{
	+ if (!_gcry_fips_mode ())
	+ return 0;
	return enforced_fips_mode;
	}

	+/* Set a flag telling whether we are in the enforced fips mode. */
	+void
	+_gcry_set_enforced_fips_mode (void)
	+{
	+ enforced_fips_mode = 1;
	+}

	/* If we do not want to enforce the fips mode, we can set a flag so
	that the application may check whether it is still in fips mode.
	TEXT will be printed as part of a syslog message. This function
	may only be be called if in fips mode. */
	void
	_gcry_inactivate_fips_mode (const char *text)
	{
	gcry_assert (_gcry_fips_mode ());

	if (_gcry_enforced_fips_mode () )
	{
	/* Get us into the error state. */
	fips_signal_error (text);
	return;
	}

	lock_fsm ();
	if (!inactive_fips_mode)
	{
	inactive_fips_mode = 1;
	unlock_fsm ();
	#ifdef HAVE_SYSLOG
	syslog (LOG_USER\|LOG_WARNING, "Libgcrypt warning: "
	"%s - FIPS mode inactivated", text);
	#endif /HAVE_SYSLOG/
	}
	else
	unlock_fsm ();
	}


	/* Return the FIPS mode inactive flag. If it is true the FIPS mode is
	not anymore active. */
	int
	_gcry_is_fips_mode_inactive (void)
	{
	int flag;

	if (!_gcry_fips_mode ())
	return 0;
	lock_fsm ();
	flag = inactive_fips_mode;
	unlock_fsm ();
	return flag;
	}



	static const char *
	state2str (enum module_states state)
	{
	const char *s;

	switch (state)
	{
	case STATE_POWERON: s = "Power-On"; break;
	case STATE_INIT: s = "Init"; break;
	case STATE_SELFTEST: s = "Self-Test"; break;
	case STATE_OPERATIONAL: s = "Operational"; break;
	case STATE_ERROR: s = "Error"; break;
	case STATE_FATALERROR: s = "Fatal-Error"; break;
	case STATE_SHUTDOWN: s = "Shutdown"; break;
	default: s = "?"; break;
	}
	return s;
	}


	/* Return true if the library is in the operational state. */
	int
	_gcry_fips_is_operational (void)
	{
	int result;

	if (!fips_mode ())
	result = 1;
	else
	{
	lock_fsm ();
	if (current_state == STATE_INIT)
	{
	/* If we are still in the INIT state, we need to run the
	selftests so that the FSM can eventually get into
	operational state. Given that we would need a 2-phase
	initialization of libgcrypt, but that has traditionally
	not been enforced, we use this on demand self-test
	checking. Note that Proper applications would do the
	application specific libgcrypt initialization between a
	gcry_check_version() and gcry_control
	(GCRYCTL_INITIALIZATION_FINISHED) where the latter will
	run the selftests. The drawback of these on-demand
	self-tests are a small chance that self-tests are
	performed by severeal threads; that is no problem because
	our FSM make sure that we won't oversee any error. */
	unlock_fsm ();
	_gcry_fips_run_selftests (0);
	lock_fsm ();
	}

	result = (current_state == STATE_OPERATIONAL);
	unlock_fsm ();
	}
	return result;
	}


	/* This is test on whether the library is in the operational state. In
	contrast to _gcry_fips_is_operational this function won't do a
	state transition on the fly. */
	int
	_gcry_fips_test_operational (void)
	{
	int result;

	if (!fips_mode ())
	result = 1;
	else
	{
	lock_fsm ();
	result = (current_state == STATE_OPERATIONAL);
	unlock_fsm ();
	}
	return result;
	}


	/* This is a test on whether the library is in the error or
	operational state. */
	int
	_gcry_fips_test_error_or_operational (void)
	{
	int result;

	if (!fips_mode ())
	result = 1;
	else
	{
	lock_fsm ();
	result = (current_state == STATE_OPERATIONAL
	\|\| current_state == STATE_ERROR);
	unlock_fsm ();
	}
	return result;
	}


	static void
	reporter (const char domain, int algo, const char what, const char *errtxt)
	{
	if (!errtxt && !_gcry_log_verbosity (2))
	return;

	log_info ("libgcrypt selftest: %s %s%s (%d): %s%s%s%s\n",
	!strcmp (domain, "hmac")? "digest":domain,
	!strcmp (domain, "hmac")? "HMAC-":"",
	!strcmp (domain, "cipher")? _gcry_cipher_algo_name (algo) :
	!strcmp (domain, "digest")? _gcry_md_algo_name (algo) :
	!strcmp (domain, "hmac")? _gcry_md_algo_name (algo) :
	!strcmp (domain, "pubkey")? _gcry_pk_algo_name (algo) : "",
	algo, errtxt? errtxt:"Okay",
	what?" (":"", what? what:"", what?")":"");
	}

	/* Run self-tests for all required cipher algorithms. Return 0 on
	success. */
	static int
	run_cipher_selftests (int extended)
	{
	static int algos[] =
	{
	GCRY_CIPHER_3DES,
	GCRY_CIPHER_AES128,
	GCRY_CIPHER_AES192,
	GCRY_CIPHER_AES256,
	0
	};
	int idx;
	gpg_error_t err;
	int anyerr = 0;

	for (idx=0; algos[idx]; idx++)
	{
	err = _gcry_cipher_selftest (algos[idx], extended, reporter);
	reporter ("cipher", algos[idx], NULL,
	err? gpg_strerror (err):NULL);
	if (err)
	anyerr = 1;
	}
	return anyerr;
	}


	/* Run self-tests for all required hash algorithms. Return 0 on
	success. */
	static int
	run_digest_selftests (int extended)
	{
	static int algos[] =
	{
	GCRY_MD_SHA1,
	GCRY_MD_SHA224,
	GCRY_MD_SHA256,
	GCRY_MD_SHA384,
	GCRY_MD_SHA512,
	0
	};
	int idx;
	gpg_error_t err;
	int anyerr = 0;

	for (idx=0; algos[idx]; idx++)
	{
	err = _gcry_md_selftest (algos[idx], extended, reporter);
	reporter ("digest", algos[idx], NULL,
	err? gpg_strerror (err):NULL);
	if (err)
	anyerr = 1;
	}
	return anyerr;
	}


	/* Run self-tests for all HMAC algorithms. Return 0 on success. */
	static int
	run_hmac_selftests (int extended)
	{
	static int algos[] =
	{
	GCRY_MD_SHA1,
	GCRY_MD_SHA224,
	GCRY_MD_SHA256,
	GCRY_MD_SHA384,
	GCRY_MD_SHA512,
	0
	};
	int idx;
	gpg_error_t err;
	int anyerr = 0;

	for (idx=0; algos[idx]; idx++)
	{
	err = _gcry_hmac_selftest (algos[idx], extended, reporter);
	reporter ("hmac", algos[idx], NULL,
	err? gpg_strerror (err):NULL);
	if (err)
	anyerr = 1;
	}
	return anyerr;
	}


	/* Run self-tests for all required public key algorithms. Return 0 on
	success. */
	static int
	run_pubkey_selftests (int extended)
	{
	static int algos[] =
	{
	GCRY_PK_RSA,
	GCRY_PK_DSA,
	/* GCRY_PK_ECDSA is not enabled in fips mode. */
	0
	};
	int idx;
	gpg_error_t err;
	int anyerr = 0;

	for (idx=0; algos[idx]; idx++)
	{
	err = _gcry_pk_selftest (algos[idx], extended, reporter);
	reporter ("pubkey", algos[idx], NULL,
	err? gpg_strerror (err):NULL);
	if (err)
	anyerr = 1;
	}
	return anyerr;
	}


	/* Run self-tests for the random number generator. Returns 0 on
	success. */
	static int
	run_random_selftests (void)
	{
	gpg_error_t err;

	err = _gcry_random_selftest (reporter);
	reporter ("random", 0, NULL, err? gpg_strerror (err):NULL);

	return !!err;
	}

	/* Run an integrity check on the binary. Returns 0 on success. */
	static int
	check_binary_integrity (void)
	{
	#ifdef ENABLE_HMAC_BINARY_CHECK
	gpg_error_t err;
	Dl_info info;
	unsigned char digest[32];
	int dlen;
	char *fname = NULL;
	const char key[] = "What am I, a doctor or a moonshuttle conductor?";

	if (!dladdr ("gcry_check_version", &info))
	err = gpg_error_from_syserror ();
	else
	{
	dlen = _gcry_hmac256_file (digest, sizeof digest, info.dli_fname,
	key, strlen (key));
	if (dlen < 0)
	err = gpg_error_from_syserror ();
	else if (dlen != 32)
	err = gpg_error (GPG_ERR_INTERNAL);
	else
	{
	fname = gcry_malloc (strlen (info.dli_fname) + 1 + 5 + 1 );
	if (!fname)
	err = gpg_error_from_syserror ();
	else
	{
	FILE *fp;
	char *p;

	/* Prefix the basename with a dot. */
	strcpy (fname, info.dli_fname);
	p = strrchr (fname, '/');
	if (p)
	p++;
	else
	p = fname;
	memmove (p+1, p, strlen (p)+1);
	*p = '.';
	strcat (fname, ".hmac");

	/* Open the file. */
	fp = fopen (fname, "r");
	if (!fp)
	err = gpg_error_from_syserror ();
	else
	{
	/* A buffer of 64 bytes plus one for a LF and one to
	detect garbage. */
	unsigned char buffer[64+1+1];
	const unsigned char *s;
	int n;

	/* The HMAC files consists of lowercase hex digits
	only with an optional trailing linefeed. Fail if
	there is any garbage. */
	err = gpg_error (GPG_ERR_SELFTEST_FAILED);
	n = fread (buffer, 1, sizeof buffer, fp);
	if (n == 64 \|\| (n == 65 && buffer[64] == '\n'))
	{
	buffer[64] = 0;
	for (n=0, s= buffer;
	n < 32 && loxdigit_p (s) && loxdigit_p (s+1);
	n++, s += 2)
	buffer[n] = loxtoi_2 (s);
	if ( n == 32 && !memcmp (digest, buffer, 32) )
	err = 0;
	}
	fclose (fp);
	}
	}
	}
	}
	reporter ("binary", 0, fname, err? gpg_strerror (err):NULL);
	#ifdef HAVE_SYSLOG
	if (err)
	syslog (LOG_USER\|LOG_ERR, "Libgcrypt error: "
	"integrity check using `%s' failed: %s",
	fname? fname:"[?]", gpg_strerror (err));
	#endif /HAVE_SYSLOG/
	gcry_free (fname);
	return !!err;
	#else
	return 0;
	#endif
	}


	/* Run the self-tests. If EXTENDED is true, extended versions of the
	selftest are run, that is more tests than required by FIPS. */
	gpg_err_code_t
	_gcry_fips_run_selftests (int extended)
	{
	enum module_states result = STATE_ERROR;
	gcry_err_code_t ec = GPG_ERR_SELFTEST_FAILED;

	if (fips_mode ())
	fips_new_state (STATE_SELFTEST);

	if (run_cipher_selftests (extended))
	goto leave;

	if (run_digest_selftests (extended))
	goto leave;

	if (run_hmac_selftests (extended))
	goto leave;

	/* Run random tests before the pubkey tests because the latter
	require random. */
	if (run_random_selftests ())
	goto leave;

	if (run_pubkey_selftests (extended))
	goto leave;

	/* Now check the integrity of the binary. We do this this after
	having checked the HMAC code. */
	if (check_binary_integrity ())
	goto leave;

	/* All selftests passed. */
	result = STATE_OPERATIONAL;
	ec = 0;

	leave:
	if (fips_mode ())
	fips_new_state (result);

	return ec;
	}


	/* This function is used to tell the FSM about errors in the library.
	The FSM will be put into an error state. This function should not
	be called directly but by one of the macros

	fips_signal_error (description)
	fips_signal_fatal_error (description)

	where DESCRIPTION is a string describing the error. */
	void
	_gcry_fips_signal_error (const char srcfile, int srcline, const char srcfunc,
	int is_fatal, const char *description)
	{
	if (!fips_mode ())
	return; /* Not required. */

	/* Set new state before printing an error. */
	fips_new_state (is_fatal? STATE_FATALERROR : STATE_ERROR);

	/* Print error. */
	log_info ("%serror in libgcrypt, file %s, line %d%s%s: %s\n",
	is_fatal? "fatal ":"",
	srcfile, srcline,
	srcfunc? ", function ":"", srcfunc? srcfunc:"",
	description? description : "no description available");
	#ifdef HAVE_SYSLOG
	syslog (LOG_USER\|LOG_ERR, "Libgcrypt error: "
	"%serror in file %s, line %d%s%s: %s",
	is_fatal? "fatal ":"",
	srcfile, srcline,
	srcfunc? ", function ":"", srcfunc? srcfunc:"",
	description? description : "no description available");
	#endif /HAVE_SYSLOG/
	}


	/* Perform a state transition to NEW_STATE. If this is an invalid
	transition, the module will go into a fatal error state. */
	static void
	fips_new_state (enum module_states new_state)
	{
	int ok = 0;
	enum module_states last_state;

	lock_fsm ();

	last_state = current_state;
	switch (current_state)
	{
	case STATE_POWERON:
	if (new_state == STATE_INIT
	\|\| new_state == STATE_ERROR
	\|\| new_state == STATE_FATALERROR)
	ok = 1;
	break;

	case STATE_INIT:
	if (new_state == STATE_SELFTEST
	\|\| new_state == STATE_ERROR
	\|\| new_state == STATE_FATALERROR)
	ok = 1;
	break;

	case STATE_SELFTEST:
	if (new_state == STATE_OPERATIONAL
	\|\| new_state == STATE_ERROR
	\|\| new_state == STATE_FATALERROR)
	ok = 1;
	break;

	case STATE_OPERATIONAL:
	if (new_state == STATE_SHUTDOWN
	\|\| new_state == STATE_SELFTEST
	\|\| new_state == STATE_ERROR
	\|\| new_state == STATE_FATALERROR)
	ok = 1;
	break;

	case STATE_ERROR:
	if (new_state == STATE_SHUTDOWN
	\|\| new_state == STATE_ERROR
	\|\| new_state == STATE_FATALERROR
	\|\| new_state == STATE_SELFTEST)
	ok = 1;
	break;

	case STATE_FATALERROR:
	if (new_state == STATE_SHUTDOWN )
	ok = 1;
	break;

	case STATE_SHUTDOWN:
	/* We won't see any transition from Shutdown because the only
	allowed new state is Power-Off and that one can't be
	represented. */
	break;

	}

	if (ok)
	{
	current_state = new_state;
	}

	unlock_fsm ();

	if (!ok \|\| _gcry_log_verbosity (2))
	log_info ("libgcrypt state transition %s => %s %s\n",
	state2str (last_state), state2str (new_state),
	ok? "granted":"denied");

	if (!ok)
	{
	/* Invalid state transition. Halting library. */
	#ifdef HAVE_SYSLOG
	syslog (LOG_USER\|LOG_ERR,
	"Libgcrypt error: invalid state transition %s => %s",
	state2str (last_state), state2str (new_state));
	#endif /HAVE_SYSLOG/
	fips_noreturn ();
	}
	else if (new_state == STATE_ERROR \|\| new_state == STATE_FATALERROR)
	{
	#ifdef HAVE_SYSLOG
	syslog (LOG_USER\|LOG_WARNING,
	"Libgcrypt notice: state transition %s => %s",
	state2str (last_state), state2str (new_state));
	#endif /HAVE_SYSLOG/
	}
	}




	/* This function should be called to ensure that the execution shall
	not continue. */
	void
	_gcry_fips_noreturn (void)
	{
	#ifdef HAVE_SYSLOG
	syslog (LOG_USER\|LOG_ERR, "Libgcrypt terminated the application");
	#endif /HAVE_SYSLOG/
	fflush (NULL);
	abort ();
	/NOTREACHED/
	}
	diff --git a/src/g10lib.h b/src/g10lib.h
	index 46d52290..ec86c976 100644
	--- a/src/g10lib.h
	+++ b/src/g10lib.h
	@@ -1,365 +1,367 @@
	/* g10lib.h - Internal definitions for libgcrypt
	* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2005
	* 2007, 2011 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, see <http://www.gnu.org/licenses/>.
	*/

	/* This header is to be used inside of libgcrypt in place of gcrypt.h.
	This way we can better distinguish between internal and external
	usage of gcrypt.h. */

	#ifndef G10LIB_H
	#define G10LIB_H 1

	#ifdef _GCRYPT_H
	#error gcrypt.h already included
	#endif

	#ifndef _GCRYPT_IN_LIBGCRYPT
	#error something is wrong with config.h
	#endif

	#include <stdio.h>
	#include <stdarg.h>

	#include "visibility.h"
	#include "types.h"




	/* Attribute handling macros. */

	#if __GNUC__ > 2 \|\| (__GNUC__ == 2 && __GNUC_MINOR__ >= 5 )
	#define JNLIB_GCC_M_FUNCTION 1
	#define JNLIB_GCC_A_NR __attribute__ ((noreturn))
	#define JNLIB_GCC_A_PRINTF( f, a ) __attribute__ ((format (printf,f,a)))
	#define JNLIB_GCC_A_NR_PRINTF( f, a ) \
	__attribute__ ((noreturn, format (printf,f,a)))
	#define GCC_ATTR_NORETURN __attribute__ ((__noreturn__))
	#else
	#define JNLIB_GCC_A_NR
	#define JNLIB_GCC_A_PRINTF( f, a )
	#define JNLIB_GCC_A_NR_PRINTF( f, a )
	#define GCC_ATTR_NORETURN
	#endif

	#if __GNUC__ >= 3
	/* According to glibc this attribute is available since 2.8 however we
	better play safe and use it only with gcc 3 or newer. */
	#define GCC_ATTR_FORMAT_ARG(a) __attribute__ ((format_arg (a)))
	#else
	#define GCC_ATTR_FORMAT_ARG(a)
	#endif


	/* Gettext macros. */

	#define _(a) _gcry_gettext(a)
	#define N_(a) (a)

	/* Some handy macros */
	#ifndef STR
	#define STR(v) #v
	#endif
	#define STR2(v) STR(v)
	#define DIM(v) (sizeof(v)/sizeof((v)[0]))
	#define DIMof(type,member) DIM(((type *)0)->member)



	/-- src/global.c -/
	int _gcry_global_is_operational (void);
	gcry_error_t _gcry_vcontrol (enum gcry_ctl_cmds cmd, va_list arg_ptr);
	void _gcry_check_heap (const void *a);
	int _gcry_get_debug_flag (unsigned int mask);


	/-- src/misc.c --/

	#if defined(JNLIB_GCC_M_FUNCTION) \|\| __STDC_VERSION__ >= 199901L
	void _gcry_bug (const char *file, int line,
	const char *func) GCC_ATTR_NORETURN;
	void _gcry_assert_failed (const char expr, const char file, int line,
	const char *func) GCC_ATTR_NORETURN;
	#else
	void _gcry_bug (const char *file, int line);
	void _gcry_assert_failed (const char expr, const char file, int line);
	#endif

	const char _gcry_gettext (const char key) GCC_ATTR_FORMAT_ARG(1);
	void _gcry_fatal_error(int rc, const char *text ) JNLIB_GCC_A_NR;
	void _gcry_log( int level, const char *fmt, ... ) JNLIB_GCC_A_PRINTF(2,3);
	void _gcry_log_bug( const char *fmt, ... ) JNLIB_GCC_A_NR_PRINTF(1,2);
	void _gcry_log_fatal( const char *fmt, ... ) JNLIB_GCC_A_NR_PRINTF(1,2);
	void _gcry_log_error( const char *fmt, ... ) JNLIB_GCC_A_PRINTF(1,2);
	void _gcry_log_info( const char *fmt, ... ) JNLIB_GCC_A_PRINTF(1,2);
	int _gcry_log_info_with_dummy_fp (FILE fp, const char fmt, ... )
	JNLIB_GCC_A_PRINTF(2,3);
	void _gcry_log_debug( const char *fmt, ... ) JNLIB_GCC_A_PRINTF(1,2);
	void _gcry_log_printf ( const char *fmt, ... ) JNLIB_GCC_A_PRINTF(1,2);
	void _gcry_log_printhex (const char text, const void buffer, size_t length);

	void _gcry_set_log_verbosity( int level );
	int _gcry_log_verbosity( int level );

	#ifdef JNLIB_GCC_M_FUNCTION
	#define BUG() _gcry_bug( __FILE__ , __LINE__, __FUNCTION__ )
	#define gcry_assert(expr) ((expr)? (void)0 \
	: _gcry_assert_failed (STR(expr), __FILE__, __LINE__, __FUNCTION__))
	#elif __STDC_VERSION__ >= 199901L
	#define BUG() _gcry_bug( __FILE__ , __LINE__, __func__ )
	#define gcry_assert(expr) ((expr)? (void)0 \
	: _gcry_assert_failed (STR(expr), __FILE__, __LINE__, __func__))
	#else
	#define BUG() _gcry_bug( __FILE__ , __LINE__ )
	#define gcry_assert(expr) ((expr)? (void)0 \
	: _gcry_assert_failed (STR(expr), __FILE__, __LINE__))
	#endif


	#define log_bug _gcry_log_bug
	#define log_fatal _gcry_log_fatal
	#define log_error _gcry_log_error
	#define log_info _gcry_log_info
	#define log_debug _gcry_log_debug
	#define log_printf _gcry_log_printf
	#define log_printhex _gcry_log_printhex


	/-- src/hwfeatures.c --/
	/* (Do not change these values unless synced with the asm code.) */
	#define HWF_PADLOCK_RNG 1
	#define HWF_PADLOCK_AES 2
	#define HWF_PADLOCK_SHA 4
	#define HWF_PADLOCK_MMUL 8

	#define HWF_INTEL_AESNI 256


	unsigned int _gcry_get_hw_features (void);
	void _gcry_detect_hw_features (unsigned int);


	/-- mpi/mpiutil.c --/
	const char *_gcry_mpi_get_hw_config (void);


	/-- cipher/pubkey.c --/

	/* FIXME: shouldn't this go into mpi.h? */
	#ifndef mpi_powm
	#define mpi_powm(w,b,e,m) gcry_mpi_powm( (w), (b), (e), (m) )
	#endif

	/-- primegen.c --/
	gcry_err_code_t _gcry_primegen_init (void);
	gcry_mpi_t _gcry_generate_secret_prime (unsigned int nbits,
	gcry_random_level_t random_level,
	int (extra_check)(void, gcry_mpi_t),
	void *extra_check_arg);
	gcry_mpi_t _gcry_generate_public_prime (unsigned int nbits,
	gcry_random_level_t random_level,
	int (extra_check)(void, gcry_mpi_t),
	void *extra_check_arg);
	gcry_mpi_t _gcry_generate_elg_prime (int mode,
	unsigned int pbits, unsigned int qbits,
	gcry_mpi_t g, gcry_mpi_t **factors);
	gcry_mpi_t _gcry_derive_x931_prime (const gcry_mpi_t xp,
	const gcry_mpi_t xp1, const gcry_mpi_t xp2,
	const gcry_mpi_t e,
	gcry_mpi_t r_p1, gcry_mpi_t r_p2);
	gpg_err_code_t _gcry_generate_fips186_2_prime
	(unsigned int pbits, unsigned int qbits,
	const void *seed, size_t seedlen,
	gcry_mpi_t r_q, gcry_mpi_t r_p,
	int *r_counter,
	void *r_seed, size_t r_seedlen);
	gpg_err_code_t _gcry_generate_fips186_3_prime
	(unsigned int pbits, unsigned int qbits,
	const void *seed, size_t seedlen,
	gcry_mpi_t r_q, gcry_mpi_t r_p,
	int *r_counter,
	void *r_seed, size_t r_seedlen, int *r_hashalgo);


	/* Replacements of missing functions (missing-string.c). */
	#ifndef HAVE_STPCPY
	char stpcpy (char a, const char *b);
	#endif
	#ifndef HAVE_STRCASECMP
	int strcasecmp (const char a, const char b) _GCRY_GCC_ATTR_PURE;
	#endif

	#include "../compat/libcompat.h"


	/* Macros used to rename missing functions. */
	#ifndef HAVE_STRTOUL
	#define strtoul(a,b,c) ((unsigned long)strtol((a),(b),(c)))
	#endif
	#ifndef HAVE_MEMMOVE
	#define memmove(d, s, n) bcopy((s), (d), (n))
	#endif
	#ifndef HAVE_STRICMP
	#define stricmp(a,b) strcasecmp( (a), (b) )
	#endif
	#ifndef HAVE_ATEXIT
	#define atexit(a) (on_exit((a),0))
	#endif
	#ifndef HAVE_RAISE
	#define raise(a) kill(getpid(), (a))
	#endif


	/* Stack burning. */

	void _gcry_burn_stack (int bytes);


	/* To avoid that a compiler optimizes certain memset calls away, these
	macros may be used instead. */
	#define wipememory2(_ptr,_set,_len) do { \
	volatile char _vptr=(volatile char )(_ptr); \
	size_t _vlen=(_len); \
	while(_vlen) { *_vptr=(_set); _vptr++; _vlen--; } \
	} while(0)
	#define wipememory(_ptr,_len) wipememory2(_ptr,0,_len)



	/* Digit predicates. */

	#define digitp(p) ((p) >= '0' && (p) <= '9')
	#define octdigitp(p) ((p) >= '0' && (p) <= '7')
	#define alphap(a) ( ((a) >= 'A' && (a) <= 'Z') \
	\|\| ((a) >= 'a' && (a) <= 'z'))
	#define hexdigitp(a) (digitp (a) \
	\|\| ((a) >= 'A' && (a) <= 'F') \
	\|\| ((a) >= 'a' && (a) <= 'f'))

	/* Management for ciphers/digests/pubkey-ciphers. */

	/* Structure for each registered `module'. */
	struct gcry_module
	{
	struct gcry_module next; / List pointers. */
	struct gcry_module **prevp;
	void spec; / Pointer to the subsystem-specific
	specification structure. */
	void extraspec; / Pointer to the subsystem-specific
	extra specification structure. */
	int flags; /* Associated flags. */
	int counter; /* Use counter. */
	unsigned int mod_id; /* ID of this module. */
	};

	/* Flags for the `flags' member of gcry_module_t. */
	#define FLAG_MODULE_DISABLED (1 << 0)

	gcry_err_code_t _gcry_module_add (gcry_module_t *entries,
	unsigned int id,
	void *spec,
	void *extraspec,
	gcry_module_t *module);

	typedef int (gcry_module_lookup_t) (void spec, void *data);

	/* Lookup a module specification by it's ID. After a successful
	lookup, the module has it's resource counter incremented. */
	gcry_module_t _gcry_module_lookup_id (gcry_module_t entries,
	unsigned int id);

	/* Internal function. Lookup a module specification. */
	gcry_module_t _gcry_module_lookup (gcry_module_t entries, void *data,
	gcry_module_lookup_t func);

	/* Release a module. In case the use-counter reaches zero, destroy
	the module. */
	void _gcry_module_release (gcry_module_t entry);

	/* Add a reference to a module. */
	void _gcry_module_use (gcry_module_t module);

	/* Return a list of module IDs. */
	gcry_err_code_t _gcry_module_list (gcry_module_t modules,
	int list, int list_length);

	gcry_err_code_t _gcry_cipher_init (void);
	gcry_err_code_t _gcry_md_init (void);
	gcry_err_code_t _gcry_pk_init (void);
	gcry_err_code_t _gcry_secmem_module_init (void);

	gcry_err_code_t _gcry_pk_module_lookup (int id, gcry_module_t *module);
	void _gcry_pk_module_release (gcry_module_t module);
	gcry_err_code_t _gcry_pk_get_elements (int algo, char enc, char sig);

	/* Memory management. */
	#define GCRY_ALLOC_FLAG_SECURE (1 << 0)


	/-- sexp.c --/
	gcry_error_t _gcry_sexp_vbuild (gcry_sexp_t retsexp, size_t erroff,
	const char *format, va_list arg_ptr);
	char *_gcry_sexp_nth_string (const gcry_sexp_t list, int number);


	/-- fips.c --/

	void _gcry_initialize_fips_mode (int force);

	int _gcry_fips_mode (void);
	#define fips_mode() _gcry_fips_mode ()

	int _gcry_enforced_fips_mode (void);

	+void _gcry_set_enforced_fips_mode (void);
	+
	void _gcry_inactivate_fips_mode (const char *text);
	int _gcry_is_fips_mode_inactive (void);


	void _gcry_fips_signal_error (const char *srcfile,
	int srcline,
	const char *srcfunc,
	int is_fatal,
	const char *description);
	#ifdef JNLIB_GCC_M_FUNCTION
	# define fips_signal_error(a) \
	_gcry_fips_signal_error (__FILE__, __LINE__, __FUNCTION__, 0, (a))
	# define fips_signal_fatal_error(a) \
	_gcry_fips_signal_error (__FILE__, __LINE__, __FUNCTION__, 1, (a))
	#else
	# define fips_signal_error(a) \
	_gcry_fips_signal_error (__FILE__, __LINE__, NULL, 0, (a))
	# define fips_signal_fatal_error(a) \
	_gcry_fips_signal_error (__FILE__, __LINE__, NULL, 1, (a))
	#endif

	int _gcry_fips_is_operational (void);
	#define fips_is_operational() (_gcry_global_is_operational ())
	#define fips_not_operational() (GCRY_GPG_ERR_NOT_OPERATIONAL)

	int _gcry_fips_test_operational (void);
	int _gcry_fips_test_error_or_operational (void);

	gpg_err_code_t _gcry_fips_run_selftests (int extended);

	void _gcry_fips_noreturn (void);
	#define fips_noreturn() (_gcry_fips_noreturn ())



	#endif /* G10LIB_H */
	diff --git a/src/gcrypt.h.in b/src/gcrypt.h.in
	index 8e23ec42..1e9d11d8 100644
	--- a/src/gcrypt.h.in
	+++ b/src/gcrypt.h.in
	@@ -1,1337 +1,1338 @@
	/* gcrypt.h - GNU Cryptographic Library Interface -- c --
	Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2006
	2007, 2008, 2009, 2010, 2011 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, 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@"

	/* 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

	#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

	/* 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_err_code_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))}



	/* The data object used to hold a multi precision integer. */
	struct gcry_mpi;
	typedef struct gcry_mpi *gcry_mpi_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



	/* 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
	{
	GCRYCTL_SET_KEY = 1,
	GCRYCTL_SET_IV = 2,
	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,
	GCRYCTL_SET_CTR = 43,
	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_DISABLE_HWF = 63,
	+ GCRYCTL_SET_ENFORCED_FIPS_FLAG = 64
	};

	/* 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-expresion 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 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);



	/*******************************************
	* *
	* 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. */
	};

	/* 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. */
	};


	/* 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. */
	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);

	/* Swap the values of A and B. */
	void gcry_mpi_swap (gcry_mpi_t a, gcry_mpi_t b);

	/* 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 int 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);


	/* 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. WARNING: Never use an opaque MPI for anything thing else then
	gcry_mpi_release, gcry_mpi_get_opaque. */
	gcry_mpi_t gcry_mpi_set_opaque (gcry_mpi_t a, 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 when the FLAG is set for A. */
	int gcry_mpi_get_flag (gcry_mpi_t a, enum gcry_mpi_flag flag);

	/* 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_set( w, u) gcry_mpi_set( (w), (u) )
	#define mpi_set_ui( w, u) gcry_mpi_set_ui( (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_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_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
	};

	/* 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. */
	};

	/* 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). */
	};


	/* 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 cioher 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);


	/* 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 )

	/* 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,
	GCRY_PK_RSA_E = 2, /* (deprecated) */
	GCRY_PK_RSA_S = 3, /* (deprecated) */
	GCRY_PK_ELG_E = 16,
	GCRY_PK_DSA = 17,
	GCRY_PK_ELG = 20,
	GCRY_PK_ECDSA = 301,
	GCRY_PK_ECDH = 302
	};

	/* 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. */

	/* 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;

	/* Please note that keygrip is still experimental and should not be
	used without contacting the author. */
	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 )




	/************************************
	* *
	* Cryptograhic Hash Functions *
	* *
	************************************/

	/* Algorithm IDs for the hash functions we know about. Not all of them
	are implemnted. */
	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. */
	};

	/* 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. */
	};

	/* (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);

	/* 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);

	/* 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);

	/* Retrieve various information about the object H. */
	gcry_error_t gcry_md_info (gcry_md_hd_t h, int what, void *buffer,
	size_t *nbytes);

	/* 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))



	/******************************
	* *
	* 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
	};

	/* 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 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
	teh 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 wether the number X is prime. */
	gcry_error_t gcry_prime_check (gcry_mpi_t x, unsigned int flags);



	/************************************
	* *
	* Miscellaneous Stuff *
	* *
	************************************/

	/* 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 bde8791c..4ce869a6 100644
	--- a/src/global.c
	+++ b/src/global.c
	@@ -1,1115 +1,1125 @@
	/* global.c - global control functions
	* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
	* 2004, 2005, 2006, 2008, 2011 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, 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 "cipher.h"
	#include "stdmem.h" /* our own memory allocator */
	#include "secmem.h" /* our own secmem allocator */
	#include "ath.h"



	/****************
	* 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;

	/* A table to map hardware features to a string. */
	static struct
	{
	unsigned int flag;
	const char *desc;
	} hwflist[] =
	{
	{ HWF_PADLOCK_RNG, "padlock-rng" },
	{ HWF_PADLOCK_AES, "padlock-aes" },
	{ HWF_PADLOCK_SHA, "padlock-sha" },
	{ HWF_PADLOCK_MMUL,"padlock-mmul"},
	{ HWF_INTEL_AESNI, "intel-aesni" },
	{ 0, NULL}
	};

	/* A bit vector with the hardware features which shall not be used.
	This variable must be set prior to any initialization. */
	static unsigned int disabled_hw_features;


	/* 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;





	/* 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;

	/* Initialize our portable thread/mutex wrapper. */
	err = ath_init ();
	if (err)
	{
	err = gpg_error_from_errno (err);
	goto fail;
	}

	/* 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 (disabled_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_pk_init ();
	if (err)
	goto fail;
	err = _gcry_primegen_init ();
	if (err)
	goto fail;
	err = _gcry_secmem_module_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;

	/* 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 ( int (fnc)(FILE fp, const char format, ...), FILE fp)
	{
	unsigned int hwf;
	int i;

	fnc (fp, "version:%s:\n", VERSION);
	fnc (fp, "ciphers:%s:\n", LIBGCRYPT_CIPHERS);
	fnc (fp, "pubkeys:%s:\n", LIBGCRYPT_PUBKEY_CIPHERS);
	fnc (fp, "digests:%s:\n", LIBGCRYPT_DIGESTS);
	fnc (fp, "rnd-mod:"
	#if USE_RNDEGD
	"egd:"
	#endif
	#if USE_RNDLINUX
	"linux:"
	#endif
	#if USE_RNDUNIX
	"unix:"
	#endif
	#if USE_RNDW32
	"w32:"
	#endif
	"\n");
	fnc (fp, "mpi-asm:%s:\n", _gcry_mpi_get_hw_config ());
	fnc (fp, "threads:%s:\n", ath_get_model (NULL));
	hwf = _gcry_get_hw_features ();
	fnc (fp, "hwflist:");
	for (i=0; hwflist[i].desc; i++)
	if ( (hwf & hwflist[i].flag) )
	fnc (fp, "%s:", hwflist[i].desc);
	fnc (fp, "\n");
	/* We use y/n instead of 1/0 for the simple reason that Emacsen's
	compile error parser would accidently flag that line when printed
	during "make check" as an error. */
	fnc (fp, "fips-mode:%c:%c:\n",
	fips_mode ()? 'y':'n',
	_gcry_enforced_fips_mode ()? 'y':'n' );
	}




	/* Command dispatcher function, acting as general control
	function. */
	gcry_error_t
	_gcry_vcontrol (enum gcry_ctl_cmds cmd, va_list arg_ptr)
	{
	static int init_finished = 0;
	gcry_err_code_t err = 0;

	switch (cmd)
	{
	case GCRYCTL_ENABLE_M_GUARD:
	_gcry_private_enable_m_guard ();
	break;

	case GCRYCTL_ENABLE_QUICK_RANDOM:
	_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 ())
	err = 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 ();
	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))
	err = GPG_ERR_GENERAL;
	break;

	case GCRYCTL_TERM_SECMEM:
	global_init ();
	_gcry_secmem_term ();
	break;

	case GCRYCTL_DISABLE_SECMEM_WARN:
	_gcry_secmem_set_flags ((_gcry_secmem_get_flags ()
	\| GCRY_SECMEM_FLAG_NO_WARNING));
	break;

	case GCRYCTL_SUSPEND_SECMEM_WARN:
	_gcry_secmem_set_flags ((_gcry_secmem_get_flags ()
	\| GCRY_SECMEM_FLAG_SUSPEND_WARNING));
	break;

	case GCRYCTL_RESUME_SECMEM_WARN:
	_gcry_secmem_set_flags ((_gcry_secmem_get_flags ()
	& ~GCRY_SECMEM_FLAG_SUSPEND_WARNING));
	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_random_seed_file (va_arg (arg_ptr, const char *));
	break;

	case GCRYCTL_UPDATE_RANDOM_SEED_FILE:
	if ( fips_is_operational () )
	_gcry_update_random_seed_file ();
	break;

	case GCRYCTL_SET_VERBOSITY:
	_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)
	err = GPG_ERR_GENERAL;
	break;

	case GCRYCTL_INITIALIZATION_FINISHED_P:
	if (init_finished)
	err = 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:
	err = ath_install (va_arg (arg_ptr, void *));
	if (!err)
	global_init ();
	break;

	case GCRYCTL_FAST_POLL:
	/* 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
	err = _gcry_rndegd_set_socket_name (va_arg (arg_ptr, const char *));
	#else
	err = gpg_error (GPG_ERR_NOT_SUPPORTED);
	#endif
	break;

	case GCRYCTL_SET_RANDOM_DAEMON_SOCKET:
	_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_random_initialize (1);
	_gcry_use_random_daemon (!! va_arg (arg_ptr, int));
	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. */
	case GCRYCTL_PRINT_CONFIG:
	{
	FILE fp = va_arg (arg_ptr, FILE );
	print_config (fp?fprintf:_gcry_log_info_with_dummy_fp, fp);
	}
	break;

	case GCRYCTL_OPERATIONAL_P:
	/* Returns true if the library is in an operational state. This
	is always true for non-fips mode. */
	if (_gcry_fips_test_operational ())
	err = GPG_ERR_GENERAL; /* Used as TRUE value */
	break;

	case GCRYCTL_FIPS_MODE_P:
	if (fips_mode ()
	&& !_gcry_is_fips_mode_inactive ()
	&& !no_secure_memory)
	err = 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. */
	if (!any_init_done)
	{
	/* Not yet intialized 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 ())
	err = 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 ();
	err = _gcry_fips_run_selftests (1);
	break;

	#if _GCRY_GCC_VERSION >= 40600
	# pragma GCC diagnostic push
	# pragma GCC diagnostic ignored "-Wswitch"
	#endif
	case 58: /* Init external random test. */
	{
	void rctx = va_arg (arg_ptr, void );
	unsigned int flags = va_arg (arg_ptr, unsigned int);
	const void key = va_arg (arg_ptr, const void );
	size_t keylen = va_arg (arg_ptr, size_t);
	const void seed = va_arg (arg_ptr, const void );
	size_t seedlen = va_arg (arg_ptr, size_t);
	const void dt = va_arg (arg_ptr, const void );
	size_t dtlen = va_arg (arg_ptr, size_t);
	if (!fips_is_operational ())
	err = fips_not_operational ();
	else
	err = _gcry_random_init_external_test (rctx, flags, key, keylen,
	seed, seedlen, dt, dtlen);
	}
	break;
	case 59: /* Run external random test. */
	{
	void ctx = va_arg (arg_ptr, void );
	void buffer = va_arg (arg_ptr, void );
	size_t buflen = va_arg (arg_ptr, size_t);
	if (!fips_is_operational ())
	err = fips_not_operational ();
	else
	err = _gcry_random_run_external_test (ctx, buffer, buflen);
	}
	break;
	case 60: /* Deinit external random test. */
	{
	void ctx = va_arg (arg_ptr, void );
	_gcry_random_deinit_external_test (ctx);
	}
	break;
	case 61: /* RFU */
	break;
	case 62: /* RFU */
	break;
	#if _GCRY_GCC_VERSION >= 40600
	# pragma GCC diagnostic pop
	#endif

	case GCRYCTL_DISABLE_HWF:
	{
	const char name = va_arg (arg_ptr, const char );
	int i;

	for (i=0; hwflist[i].desc; i++)
	if (!strcmp (hwflist[i].desc, name))
	{
	disabled_hw_features \|= hwflist[i].flag;
	break;
	}
	if (!hwflist[i].desc)
	err = GPG_ERR_INV_NAME;
	}
	break;

	+ case GCRYCTL_SET_ENFORCED_FIPS_FLAG:
	+ if (!any_init_done)
	+ {
	+ /* Not yet intialized at all. Set the enforced fips mode flag */
	+ _gcry_set_enforced_fips_mode ();
	+ }
	+ else
	+ err = GPG_ERR_GENERAL;
	+ break;
	+
	default:
	/* A call to make sure that the dummy code is linked in. */
	_gcry_compat_identification ();
	err = GPG_ERR_INV_OP;
	}

	return gcry_error (err);
	}


	/* Command dispatcher function, acting as general control
	function. */
	gcry_error_t
	gcry_control (enum gcry_ctl_cmds cmd, ...)
	{
	gcry_error_t err;
	va_list arg_ptr;

	va_start (arg_ptr, cmd);
	err = _gcry_vcontrol (cmd, arg_ptr);
	va_end(arg_ptr);
	return 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 gpg_strerror (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)
	{
	return gpg_strsource (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)
	{
	return gpg_err_code_from_errno (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 gpg_err_code_from_errno (code);
	}


	/* Return an error value with the error source SOURCE and the system
	error ERR. */
	gcry_error_t
	gcry_err_make_from_errno (gpg_err_source_t source, int err)
	{
	return gpg_err_make_from_errno (source, err);
	}


	/* Return an error value with the system error ERR. */
	gcry_err_code_t
	gcry_error_from_errno (int err)
	{
	return gcry_error (gpg_err_code_from_errno (err));
	}


	/* 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);
	}
	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;
	}

	void *
	gcry_malloc_secure (size_t n)
	{
	void *mem = NULL;

	do_malloc (n, GCRY_ALLOC_FLAG_SECURE, &mem);

	return mem;
	}

	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
	}

	void *
	gcry_realloc (void *a, size_t n)
	{
	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)
	{
	gcry_free (a);
	return NULL;
	}

	if (realloc_func)
	p = realloc_func (a, n);
	else
	p = _gcry_private_realloc (a, n);
	if (!p && !errno)
	gpg_err_set_errno (ENOMEM);
	return p;
	}

	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 accidently 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;
	}


	/* 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)
	{
	char *string_cp = NULL;
	size_t string_n = 0;

	string_n = strlen (string);

	if (gcry_is_secure (string))
	string_cp = gcry_malloc_secure (string_n + 1);
	else
	string_cp = gcry_malloc (string_n + 1);

	if (string_cp)
	strcpy (string_cp, string);

	return string_cp;
	}


	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( a, n )) )
	{
	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( n )) )
	{
	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 (string)) )
	{
	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;
	}


	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);
	}

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