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/* sha256.c
*
* The sha256 hash function.
*
* See http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001 Niels Möller
*
* The nettle library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The nettle library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
/* Modelled after the sha1.c code by Peter Gutmann. */
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "sha.h"
#include "macros.h"
#include "nettle-write.h"
/* Generated by the shadata program. */
static const uint32_t
K[64] =
{
0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL,
0x3956c25bUL, 0x59f111f1UL, 0x923f82a4UL, 0xab1c5ed5UL,
0xd807aa98UL, 0x12835b01UL, 0x243185beUL, 0x550c7dc3UL,
0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL, 0xc19bf174UL,
0xe49b69c1UL, 0xefbe4786UL, 0xfc19dc6UL, 0x240ca1ccUL,
0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL,
0x983e5152UL, 0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL,
0xc6e00bf3UL, 0xd5a79147UL, 0x6ca6351UL, 0x14292967UL,
0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL, 0x53380d13UL,
0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL,
0xa2bfe8a1UL, 0xa81a664bUL, 0xc24b8b70UL, 0xc76c51a3UL,
0xd192e819UL, 0xd6990624UL, 0xf40e3585UL, 0x106aa070UL,
0x19a4c116UL, 0x1e376c08UL, 0x2748774cUL, 0x34b0bcb5UL,
0x391c0cb3UL, 0x4ed8aa4aUL, 0x5b9cca4fUL, 0x682e6ff3UL,
0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL,
0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL,
};
/* Initialize the SHA values */
void
sha256_init(struct sha256_ctx *ctx)
{
/* Initial values, also generated by the shadata program. */
static const uint32_t H0[_SHA256_DIGEST_LENGTH] =
{
0x6a09e667UL, 0xbb67ae85UL, 0x3c6ef372UL, 0xa54ff53aUL,
0x510e527fUL, 0x9b05688cUL, 0x1f83d9abUL, 0x5be0cd19UL,
};
memcpy(ctx->state, H0, sizeof(H0));
/* Initialize bit count */
ctx->count_low = ctx->count_high = 0;
/* Initialize buffer */
ctx->index = 0;
}
#define SHA256_INCR(ctx) ((ctx)->count_high += !++(ctx)->count_low)
void
sha256_update(struct sha256_ctx *ctx,
unsigned length, const uint8_t *buffer)
{
if (ctx->index)
{ /* Try to fill partial block */
unsigned left = SHA256_DATA_SIZE - ctx->index;
if (length < left)
{
memcpy(ctx->block + ctx->index, buffer, length);
ctx->index += length;
return; /* Finished */
}
else
{
memcpy(ctx->block + ctx->index, buffer, left);
_nettle_sha256_compress(ctx->state, ctx->block, K);
SHA256_INCR(ctx);
buffer += left;
length -= left;
}
}
while (length >= SHA256_DATA_SIZE)
{
_nettle_sha256_compress(ctx->state, buffer, K);
SHA256_INCR(ctx);
buffer += SHA256_DATA_SIZE;
length -= SHA256_DATA_SIZE;
}
/* Buffer leftovers */
/* NOTE: The corresponding sha1 code checks for the special case length == 0.
* That seems supoptimal, as I suspect it increases the number of branches. */
memcpy(ctx->block, buffer, length);
ctx->index = length;
}
/* Final wrapup - pad to SHA1_DATA_SIZE-byte boundary with the bit pattern
1 0* (64-bit count of bits processed, MSB-first) */
static void
sha256_final(struct sha256_ctx *ctx)
{
uint32_t bitcount_high;
uint32_t bitcount_low;
int i;
i = ctx->index;
/* Set the first char of padding to 0x80. This is safe since there is
always at least one byte free */
assert(i < SHA256_DATA_SIZE);
ctx->block[i++] = 0x80;
if (i > (SHA1_DATA_SIZE - 8))
{ /* No room for length in this block. Process it and
* pad with another one */
memset(ctx->block + i, 0, SHA256_DATA_SIZE - i);
_nettle_sha256_compress(ctx->state, ctx->block, K);
i = 0;
}
if (i < (SHA256_DATA_SIZE - 8))
memset(ctx->block + i, 0, (SHA256_DATA_SIZE - 8) - i);
/* There are 512 = 2^9 bits in one block */
bitcount_high = (ctx->count_high << 9) | (ctx->count_low >> 23);
bitcount_low = (ctx->count_low << 9) | (ctx->index << 3);
/* This is slightly inefficient, as the numbers are converted to
big-endian format, and will be converted back by the compression
function. It's probably not worth the effort to fix this. */
WRITE_UINT32(ctx->block + (SHA256_DATA_SIZE - 8), bitcount_high);
WRITE_UINT32(ctx->block + (SHA256_DATA_SIZE - 4), bitcount_low);
_nettle_sha256_compress(ctx->state, ctx->block, K);
}
void
sha256_digest(struct sha256_ctx *ctx,
unsigned length,
uint8_t *digest)
{
assert(length <= SHA256_DIGEST_SIZE);
sha256_final(ctx);
_nettle_write_be32(length, digest, ctx->state);
sha256_init(ctx);
}
/* sha224 variant. FIXME: Move to seperate file? */
void
sha224_init(struct sha256_ctx *ctx)
{
/* Initial values. I's unclear how they are chosen. */
static const uint32_t H0[_SHA256_DIGEST_LENGTH] =
{
0xc1059ed8, 0x367cd507, 0x3070dd17, 0xf70e5939,
0xffc00b31, 0x68581511, 0x64f98fa7, 0xbefa4fa4,
};
memcpy(ctx->state, H0, sizeof(H0));
/* Initialize bit count */
ctx->count_low = ctx->count_high = 0;
/* Initialize buffer */
ctx->index = 0;
}
void
sha224_digest(struct sha256_ctx *ctx,
unsigned length,
uint8_t *digest)
{
assert(length <= SHA224_DIGEST_SIZE);
sha256_final(ctx);
_nettle_write_be32(length, digest, ctx->state);
sha224_init(ctx);
}
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