diff options
author | brian m. carlson <sandals@crustytoothpaste.net> | 2018-11-14 07:09:36 +0300 |
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committer | Junio C Hamano <gitster@pobox.com> | 2018-11-14 10:54:53 +0300 |
commit | 13eeedb5d17ca3539600b6618d103b652ecc8ab0 (patch) | |
tree | 4b4dd03dafa7c67d234c8f6da3e49c4a80234f76 /sha256/block/sha256.c | |
parent | c166599862d10a273f61b834559eaa567c3dbfd9 (diff) |
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 <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'sha256/block/sha256.c')
-rw-r--r-- | sha256/block/sha256.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/sha256/block/sha256.c b/sha256/block/sha256.c new file mode 100644 index 0000000000..37850b4e52 --- /dev/null +++ b/sha256/block/sha256.c @@ -0,0 +1,196 @@ +#include "git-compat-util.h" +#include "./sha256.h" + +#undef RND +#undef BLKSIZE + +#define BLKSIZE blk_SHA256_BLKSIZE + +void blk_SHA256_Init(blk_SHA256_CTX *ctx) +{ + ctx->offset = 0; + ctx->size = 0; + ctx->state[0] = 0x6a09e667ul; + ctx->state[1] = 0xbb67ae85ul; + ctx->state[2] = 0x3c6ef372ul; + ctx->state[3] = 0xa54ff53aul; + ctx->state[4] = 0x510e527ful; + ctx->state[5] = 0x9b05688cul; + ctx->state[6] = 0x1f83d9abul; + ctx->state[7] = 0x5be0cd19ul; +} + +static inline uint32_t ror(uint32_t x, unsigned n) +{ + return (x >> n) | (x << (32 - n)); +} + +static inline uint32_t ch(uint32_t x, uint32_t y, uint32_t z) +{ + return z ^ (x & (y ^ z)); +} + +static inline uint32_t maj(uint32_t x, uint32_t y, uint32_t z) +{ + return ((x | y) & z) | (x & y); +} + +static inline uint32_t sigma0(uint32_t x) +{ + return ror(x, 2) ^ ror(x, 13) ^ ror(x, 22); +} + +static inline uint32_t sigma1(uint32_t x) +{ + return ror(x, 6) ^ ror(x, 11) ^ ror(x, 25); +} + +static inline uint32_t gamma0(uint32_t x) +{ + return ror(x, 7) ^ ror(x, 18) ^ (x >> 3); +} + +static inline uint32_t gamma1(uint32_t x) +{ + return ror(x, 17) ^ ror(x, 19) ^ (x >> 10); +} + +static void blk_SHA256_Transform(blk_SHA256_CTX *ctx, const unsigned char *buf) +{ + + uint32_t S[8], W[64], t0, t1; + int i; + + /* copy state into S */ + for (i = 0; i < 8; i++) + S[i] = ctx->state[i]; + + /* copy the state into 512-bits into W[0..15] */ + for (i = 0; i < 16; i++, buf += sizeof(uint32_t)) + W[i] = get_be32(buf); + + /* fill W[16..63] */ + for (i = 16; i < 64; i++) + W[i] = gamma1(W[i - 2]) + W[i - 7] + gamma0(W[i - 15]) + W[i - 16]; + +#define RND(a,b,c,d,e,f,g,h,i,ki) \ + t0 = h + sigma1(e) + ch(e, f, g) + ki + W[i]; \ + t1 = sigma0(a) + maj(a, b, c); \ + d += t0; \ + h = t0 + t1; + + RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],0,0x428a2f98); + RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],1,0x71374491); + RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],2,0xb5c0fbcf); + RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],3,0xe9b5dba5); + RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],4,0x3956c25b); + RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],5,0x59f111f1); + RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],6,0x923f82a4); + RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],7,0xab1c5ed5); + RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],8,0xd807aa98); + RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],9,0x12835b01); + RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],10,0x243185be); + RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],11,0x550c7dc3); + RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],12,0x72be5d74); + RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],13,0x80deb1fe); + RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],14,0x9bdc06a7); + RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],15,0xc19bf174); + RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],16,0xe49b69c1); + RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],17,0xefbe4786); + RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],18,0x0fc19dc6); + RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],19,0x240ca1cc); + RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],20,0x2de92c6f); + RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],21,0x4a7484aa); + RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],22,0x5cb0a9dc); + RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],23,0x76f988da); + RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],24,0x983e5152); + RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],25,0xa831c66d); + RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],26,0xb00327c8); + RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],27,0xbf597fc7); + RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],28,0xc6e00bf3); + RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],29,0xd5a79147); + RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],30,0x06ca6351); + RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],31,0x14292967); + RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],32,0x27b70a85); + RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],33,0x2e1b2138); + RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],34,0x4d2c6dfc); + RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],35,0x53380d13); + RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],36,0x650a7354); + RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],37,0x766a0abb); + RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],38,0x81c2c92e); + RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],39,0x92722c85); + RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],40,0xa2bfe8a1); + RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],41,0xa81a664b); + RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],42,0xc24b8b70); + RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],43,0xc76c51a3); + RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],44,0xd192e819); + RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],45,0xd6990624); + RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],46,0xf40e3585); + RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],47,0x106aa070); + RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],48,0x19a4c116); + RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],49,0x1e376c08); + RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],50,0x2748774c); + RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],51,0x34b0bcb5); + RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],52,0x391c0cb3); + RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],53,0x4ed8aa4a); + RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],54,0x5b9cca4f); + RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],55,0x682e6ff3); + RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],56,0x748f82ee); + RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],57,0x78a5636f); + RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],58,0x84c87814); + RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],59,0x8cc70208); + RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],60,0x90befffa); + RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],61,0xa4506ceb); + RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],62,0xbef9a3f7); + RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],63,0xc67178f2); + + for (i = 0; i < 8; i++) + ctx->state[i] += S[i]; +} + +void blk_SHA256_Update(blk_SHA256_CTX *ctx, const void *data, size_t len) +{ + unsigned int len_buf = ctx->size & 63; + + ctx->size += len; + + /* Read the data into buf and process blocks as they get full */ + if (len_buf) { + unsigned int left = 64 - len_buf; + if (len < left) + left = len; + memcpy(len_buf + ctx->buf, data, left); + len_buf = (len_buf + left) & 63; + len -= left; + data = ((const char *)data + left); + if (len_buf) + return; + blk_SHA256_Transform(ctx, ctx->buf); + } + while (len >= 64) { + blk_SHA256_Transform(ctx, data); + data = ((const char *)data + 64); + len -= 64; + } + if (len) + memcpy(ctx->buf, data, len); +} + +void blk_SHA256_Final(unsigned char *digest, blk_SHA256_CTX *ctx) +{ + static const unsigned char pad[64] = { 0x80 }; + unsigned int padlen[2]; + int i; + + /* Pad with a binary 1 (ie 0x80), then zeroes, then length */ + padlen[0] = htonl((uint32_t)(ctx->size >> 29)); + padlen[1] = htonl((uint32_t)(ctx->size << 3)); + + i = ctx->size & 63; + blk_SHA256_Update(ctx, pad, 1 + (63 & (55 - i))); + blk_SHA256_Update(ctx, padlen, 8); + + /* copy output */ + for (i = 0; i < 8; i++, digest += sizeof(uint32_t)) + put_be32(digest, ctx->state[i]); +} |