Re: [PATCH] sha256: add support for Nettle

Junio C Hamano <gitster@pobox.com> writes:

Taking all together, here is a copy I have in my tree right now (see the range diff for what changed since your initial version).

Thanks.

----- >8 --------- >8 --------- >8 --------- >8 --------- >8 -----
From e8713290975d171764768bea99d686243e23ef8e Mon Sep 17 00:00:00 2001
From: "brian m. carlson" <sandals@crustytoothpaste.net>
Date: Tue, 5 Jul 2022 23:05:18 +0000
Subject: [PATCH] sha256: add support for Nettle

For SHA-256, we currently have support for OpenSSL and libgcrypt because these two libraries contain optimized implementations that can take advantage of native processor instructions. However, OpenSSL is not suitable for linking against for Linux distros due to licensing incompatibilities with the GPLv2, and libgcrypt has been less favored by cryptographers due to some security-related implementation issues.

Let's add another option that's compatible with the GPLv2, which is Nettle, and give it preference over all others when Nettle and other choices are possible. It also has recently gained support for Intel's SHA-NI instructions, which compare very favorably to other implementations. For example, using this implementation and SHA-1 DC on a machine with SHA-NI, hashing a 2 GiB file with SHA-1 takes 7.582 seconds, while hashing the same file with SHA-256 takes 2.278 seconds.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

1:  3bcd13c813 ! 1:  e871329097 sha256: add support for Nettle
    @@ Commit message
         by cryptographers due to some security-related implementation issues.
     
         Let's add another option that's compatible with the GPLv2, which is
    -    Nettle.  It also has recently gained support for Intel's SHA-NI
    -    instructions, which compare very favorably to other implementations.
    -    For example, using this implementation and SHA-1 DC on a machine with
    -    SHA-NI, hashing a 2 GiB file with SHA-1 takes 7.582 seconds, while
    -    hashing the same file with SHA-256 takes 2.278 seconds.
    +    Nettle, and give it preference over all others when Nettle and other
    +    choices are possible.  It also has recently gained support for
    +    Intel's SHA-NI instructions, which compare very favorably to other
    +    implementations.  For example, using this implementation and SHA-1
    +    DC on a machine with SHA-NI, hashing a 2 GiB file with SHA-1 takes
    +    7.582 seconds, while hashing the same file with SHA-256 takes 2.278
    +    seconds.
     
         Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
         Signed-off-by: Junio C Hamano <gitster@pobox.com>
    @@ Makefile: else
      
      ifdef SHA1_MAX_BLOCK_SIZE
      	LIB_OBJS += compat/sha1-chunked.o
    +@@ Makefile: $(SP_OBJ): %.sp: %.c %.o
    + sparse: $(SP_OBJ)
    + 
    + EXCEPT_HDRS := $(GENERATED_H) unicode-width.h compat/% xdiff/%
    ++ifndef NETTLE_SHA256
    ++	EXCEPT_HDRS += sha256/nettle.h
    ++endif
    + ifndef GCRYPT_SHA256
    + 	EXCEPT_HDRS += sha256/gcrypt.h
    + endif
     
      ## hash.h ##
     @@
    @@ hash.h
     
      ## sha256/nettle.h (new) ##
     @@
    -+#ifndef SHA256_GCRYPT_H
    -+#define SHA256_GCRYPT_H
    ++#ifndef SHA256_NETTLE_H
    ++#define SHA256_NETTLE_H
     +
     +#include <nettle/sha2.h>
     +
     +typedef struct sha256_ctx nettle_SHA256_CTX;
     +
    -+inline void nettle_SHA256_Init(nettle_SHA256_CTX *ctx)
    ++static inline void nettle_SHA256_Init(nettle_SHA256_CTX *ctx)
     +{
     +	sha256_init(ctx);
     +}
     +
    -+inline void nettle_SHA256_Update(nettle_SHA256_CTX *ctx, const void *data, size_t len)
    ++static inline void nettle_SHA256_Update(nettle_SHA256_CTX *ctx, const void *data, size_t len)
     +{
     +	sha256_update(ctx, len, data);
     +}
     +
    -+inline void nettle_SHA256_Final(unsigned char *digest, nettle_SHA256_CTX *ctx)
    ++static inline void nettle_SHA256_Final(unsigned char *digest, nettle_SHA256_CTX *ctx)
     +{
     +	sha256_digest(ctx, SHA256_DIGEST_SIZE, digest);
     +}

 Makefile        | 10 ++++++++++
 hash.h          |  4 +++-
 sha256/nettle.h | 28 ++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 sha256/nettle.h