From 13eeedb5d17ca3539600b6618d103b652ecc8ab0 Mon Sep 17 00:00:00 2001 From: "brian m. carlson" Date: Wed, 14 Nov 2018 04:09:36 +0000 Subject: Add a base implementation of SHA-256 support SHA-1 is weak and we need to transition to a new hash function. For some time, we have referred to this new function as NewHash. Recently, we decided to pick SHA-256 as NewHash. The reasons behind the choice of SHA-256 are outlined in the thread starting at [1] and in the commit history for the hash function transition document. Add a basic implementation of SHA-256 based off libtomcrypt, which is in the public domain. Optimize it and restructure it to meet our coding standards. Pull in the update and final functions from the SHA-1 block implementation, as we know these function correctly with all compilers. This implementation is slower than SHA-1, but more performant implementations will be introduced in future commits. Wire up SHA-256 in the list of hash algorithms, and add a test that the algorithm works correctly. Note that with this patch, it is still not possible to switch to using SHA-256 in Git. Additional patches are needed to prepare the code to handle a larger hash algorithm and further test fixes are needed. [1] https://public-inbox.org/git/20180609224913.GC38834@genre.crustytoothpaste.net/ Signed-off-by: brian m. carlson Signed-off-by: Junio C Hamano --- hash.h | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) (limited to 'hash.h') diff --git a/hash.h b/hash.h index 1bcf7ab6fd..a9bc624020 100644 --- a/hash.h +++ b/hash.h @@ -15,6 +15,8 @@ #include "block-sha1/sha1.h" #endif +#include "sha256/block/sha256.h" + #ifndef platform_SHA_CTX /* * platform's underlying implementation of SHA-1; could be OpenSSL, @@ -34,6 +36,18 @@ #define git_SHA1_Update platform_SHA1_Update #define git_SHA1_Final platform_SHA1_Final +#ifndef platform_SHA256_CTX +#define platform_SHA256_CTX SHA256_CTX +#define platform_SHA256_Init SHA256_Init +#define platform_SHA256_Update SHA256_Update +#define platform_SHA256_Final SHA256_Final +#endif + +#define git_SHA256_CTX platform_SHA256_CTX +#define git_SHA256_Init platform_SHA256_Init +#define git_SHA256_Update platform_SHA256_Update +#define git_SHA256_Final platform_SHA256_Final + #ifdef SHA1_MAX_BLOCK_SIZE #include "compat/sha1-chunked.h" #undef git_SHA1_Update @@ -52,12 +66,15 @@ #define GIT_HASH_UNKNOWN 0 /* SHA-1 */ #define GIT_HASH_SHA1 1 +/* SHA-256 */ +#define GIT_HASH_SHA256 2 /* Number of algorithms supported (including unknown). */ -#define GIT_HASH_NALGOS (GIT_HASH_SHA1 + 1) +#define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1) /* A suitably aligned type for stack allocations of hash contexts. */ union git_hash_ctx { git_SHA_CTX sha1; + git_SHA256_CTX sha256; }; typedef union git_hash_ctx git_hash_ctx; -- cgit v1.2.3