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/*
* cifra - embedded cryptography library
* Written in 2014 by Joseph Birr-Pixton <jpixton@gmail.com>
*
* To the extent possible under law, the author(s) have dedicated all
* copyright and related and neighboring rights to this software to the
* public domain worldwide. This software is distributed without any
* warranty.
*
* You should have received a copy of the CC0 Public Domain Dedication
* along with this software. If not, see
* <http://creativecommons.org/publicdomain/zero/1.0/>.
*/
#include <string.h>
#include "sha1.h"
#include "blockwise.h"
#include "bitops.h"
#include "handy.h"
#include "tassert.h"
void cf_sha1_init(cf_sha1_context *ctx)
{
memset(ctx, 0, sizeof *ctx);
ctx->H[0] = 0x67452301;
ctx->H[1] = 0xefcdab89;
ctx->H[2] = 0x98badcfe;
ctx->H[3] = 0x10325476;
ctx->H[4] = 0xc3d2e1f0;
}
static void sha1_update_block(void *vctx, const uint8_t *inp)
{
cf_sha1_context *ctx = vctx;
/* This is a 16-word window into the whole W array. */
uint32_t W[16];
uint32_t a = ctx->H[0],
b = ctx->H[1],
c = ctx->H[2],
d = ctx->H[3],
e = ctx->H[4],
Wt;
for (size_t t = 0; t < 80; t++)
{
/* For W[0..16] we process the input into W.
* For W[16..79] we compute the next W value:
*
* W[t] = (W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16]) <<< 1
*
* But all W indices are reduced mod 16 into our window.
*/
if (t < 16)
{
W[t] = Wt = read32_be(inp);
inp += 4;
} else {
Wt = W[(t - 3) % 16] ^ W[(t - 8) % 16] ^ W[(t - 14) % 16] ^ W[(t - 16) % 16];
Wt = rotl32(Wt, 1);
W[t % 16] = Wt;
}
uint32_t f, k;
if (t <= 19)
{
f = (b & c) | (~b & d);
k = 0x5a827999;
} else if (t <= 39) {
f = b ^ c ^ d;
k = 0x6ed9eba1;
} else if (t <= 59) {
f = (b & c) | (b & d) | (c & d);
k = 0x8f1bbcdc;
} else {
f = b ^ c ^ d;
k = 0xca62c1d6;
}
uint32_t temp = rotl32(a, 5) + f + e + k + Wt;
e = d;
d = c;
c = rotl32(b, 30);
b = a;
a = temp;
}
ctx->H[0] += a;
ctx->H[1] += b;
ctx->H[2] += c;
ctx->H[3] += d;
ctx->H[4] += e;
ctx->blocks++;
}
void cf_sha1_update(cf_sha1_context *ctx, const void *data, size_t nbytes)
{
cf_blockwise_accumulate(ctx->partial, &ctx->npartial, sizeof ctx->partial,
data, nbytes,
sha1_update_block, ctx);
}
void cf_sha1_digest(const cf_sha1_context *ctx, uint8_t hash[CF_SHA1_HASHSZ])
{
cf_sha1_context ours = *ctx;
cf_sha1_digest_final(&ours, hash);
}
void cf_sha1_digest_final(cf_sha1_context *ctx, uint8_t hash[CF_SHA1_HASHSZ])
{
uint64_t digested_bytes = ctx->blocks;
digested_bytes = digested_bytes * CF_SHA1_BLOCKSZ + ctx->npartial;
uint64_t digested_bits = digested_bytes * 8;
size_t padbytes = CF_SHA1_BLOCKSZ - ((digested_bytes + 8) % CF_SHA1_BLOCKSZ);
/* Hash 0x80 00 ... block first. */
cf_blockwise_acc_pad(ctx->partial, &ctx->npartial, sizeof ctx->partial,
0x80, 0x00, 0x00, padbytes,
sha1_update_block, ctx);
/* Now hash length. */
uint8_t buf[8];
write64_be(digested_bits, buf);
cf_sha1_update(ctx, buf, 8);
/* We ought to have got our padding calculation right! */
assert(ctx->npartial == 0);
write32_be(ctx->H[0], hash + 0);
write32_be(ctx->H[1], hash + 4);
write32_be(ctx->H[2], hash + 8);
write32_be(ctx->H[3], hash + 12);
write32_be(ctx->H[4], hash + 16);
memset(ctx, 0, sizeof *ctx);
}
const cf_chash cf_sha1 = {
.hashsz = CF_SHA1_HASHSZ,
.blocksz = CF_SHA1_BLOCKSZ,
.init = (cf_chash_init) cf_sha1_init,
.update = (cf_chash_update) cf_sha1_update,
.digest = (cf_chash_digest) cf_sha1_digest
};
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