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sha256: add an SHA-256 implementation using libgcrypt 

Generally, one gets better performance out of cryptographic routines
written in assembly than C, and this is also true for SHA-256.  In
addition, most Linux distributions cannot distribute Git linked against
OpenSSL for licensing reasons.

Most systems with GnuPG will also have libgcrypt, since it is a
dependency of GnuPG.  libgcrypt is also faster than the SHA1DC
implementation for messages of a few KiB and larger.

For comparison, on a Core i7-6600U, this implementation processes 16 KiB
chunks at 355 MiB/s while SHA1DC processes equivalent chunks at 337
MiB/s.

In addition, libgcrypt is licensed under the LGPL 2.1, which is
compatible with the GPL.  Add an implementation of SHA-256 that uses
libgcrypt.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
brian m. carlson 2018-11-14 04:09:37 +00:00 committed by Junio C Hamano
parent 13eeedb5d1
commit 27dc04c545
3 changed files with 45 additions and 2 deletions
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13
Makefile
View File

@ -179,6 +179,10 @@ all::
# in one call to the platform's SHA1_Update(). e.g. APPLE_COMMON_CRYPTO
# wants 'SHA1_MAX_BLOCK_SIZE=1024L*1024L*1024L' defined.
#
# Define BLK_SHA256 to use the built-in SHA-256 routines.
#
# Define GCRYPT_SHA256 to use the SHA-256 routines in libgcrypt.
#
# Define NEEDS_CRYPTO_WITH_SSL if you need -lcrypto when using -lssl (Darwin).
#
# Define NEEDS_SSL_WITH_CRYPTO if you need -lssl when using -lcrypto (Darwin).
@ -1634,8 +1638,13 @@ endif
endif
endif
LIB_OBJS += sha256/block/sha256.o
BASIC_CFLAGS += -DSHA256_BLK
ifdef GCRYPT_SHA256
BASIC_CFLAGS += -DSHA256_GCRYPT
EXTLIBS += -lgcrypt
else
LIB_OBJS += sha256/block/sha256.o
BASIC_CFLAGS += -DSHA256_BLK
endif
ifdef SHA1_MAX_BLOCK_SIZE
LIB_OBJS += compat/sha1-chunked.o

4
hash.h
View File

@ -15,7 +15,11 @@
#include "block-sha1/sha1.h"
#endif
#if defined(SHA256_GCRYPT)
#include "sha256/gcrypt.h"
#else
#include "sha256/block/sha256.h"
#endif
#ifndef platform_SHA_CTX
/*

30
sha256/gcrypt.h Normal file
View File

@ -0,0 +1,30 @@
#ifndef SHA256_GCRYPT_H
#define SHA256_GCRYPT_H
#include <gcrypt.h>
#define SHA256_DIGEST_SIZE 32
typedef gcry_md_hd_t gcrypt_SHA256_CTX;
inline void gcrypt_SHA256_Init(gcrypt_SHA256_CTX *ctx)
{
gcry_md_open(ctx, GCRY_MD_SHA256, 0);
}
inline void gcrypt_SHA256_Update(gcrypt_SHA256_CTX *ctx, const void *data, size_t len)
{
gcry_md_write(*ctx, data, len);
}
inline void gcrypt_SHA256_Final(unsigned char *digest, gcrypt_SHA256_CTX *ctx)
{
memcpy(digest, gcry_md_read(*ctx, GCRY_MD_SHA256), SHA256_DIGEST_SIZE);
}
#define platform_SHA256_CTX gcrypt_SHA256_CTX
#define platform_SHA256_Init gcrypt_SHA256_Init
#define platform_SHA256_Update gcrypt_SHA256_Update
#define platform_SHA256_Final gcrypt_SHA256_Final
#endif