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>
diff --git a/Makefile b/Makefile
index 76d378c..3d91555 100644
--- a/Makefile
+++ b/Makefile
@@ -179,6 +179,10 @@
# 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
-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
