md: add variable length output interface
* cipher/crc.c (_gcry_digest_spec_crc32) (_gcry_digest_spec_crc32_rfc1510, _gcry_digest_spec_crc24_rfc2440): Set 'extract' NULL. * cipher/gostr3411-94.c (_gcry_digest_spec_gost3411_94) (_gcry_digest_spec_gost3411_cp): Ditto. * cipher/keccak.c (_gcry_digest_spec_sha3_224) (_gcry_digest_spec_sha3_256, _gcry_digest_spec_sha3_384) (_gcry_digest_spec_sha3_512): Ditto. * cipher/md2.c (_gcry_digest_spec_md2): Ditto. * cipher/md4.c (_gcry_digest_spec_md4): Ditto. * cipher/md5.c (_gcry_digest_spec_md5): Ditto. * cipher/rmd160.c (_gcry_digest_spec_rmd160): Ditto. * cipher/sha1.c (_gcry_digest_spec_sha1): Ditto. * cipher/sha256.c (_gcry_digest_spec_sha224) (_gcry_digest_spec_sha256): Ditto. * cipher/sha512.c (_gcry_digest_spec_sha384) (_gcry_digest_spec_sha512): Ditto. * cipher/stribog.c (_gcry_digest_spec_stribog_256) (_gcry_digest_spec_stribog_512): Ditto. * cipher/tiger.c (_gcry_digest_spec_tiger) (_gcry_digest_spec_tiger1, _gcry_digest_spec_tiger2): Ditto. * cipher/whirlpool.c (_gcry_digest_spec_whirlpool): Ditto. * cipher/md.c (md_enable): Do not allow combination of HMAC and 'expandable-output function'. (md_final): Check if spec->read is NULL before calling. (md_read): Ditto. (md_extract, _gcry_md_extract): New. * doc/gcrypt.texi: Add SHA3 algorithms and gcry_md_extract. * src/cipher-proto.h (gcry_md_extract_t): New. (gcry_md_spec_t): Add 'extract'. * src/gcrypt-int.g (_gcry_md_extract): New. * src/gcrypt.h.in (gcry_md_extract): New. * src/libgcrypt.def: Add gcry_md_extract. * src/libgcrypt.vers: Add gcry_md_extract. * src/visibility.c (gcry_md_extract): New. * src/visibility.h (gcry_md_extract): New.
Patch adds new interface for reading output from 'expandable-output
function' MD algorithms that can give variable length output (ie.
SHAKE algorithms from FIPS-202). New function to read output is
gpg_error_t gcry_md_extract(gcry_md_hd_t md, int algo,
void *buffer, size_t length);
Function implicitly finalizes algorithm so that no new input can
be given. Subsequents calls of the function return more output
bytes from the algorithm.
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>