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/* sha1.c
*
* The sha1 hash function.
* Defined by http://www.itl.nist.gov/fipspubs/fip180-1.htm.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001 Peter Gutmann, Andrew Kuchling, 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.
*/
/* Here's the first paragraph of Peter Gutmann's posting,
* <30ajo5$oe8@ccu2.auckland.ac.nz>:
*
* The following is my SHA (FIPS 180) code updated to allow use of the "fixed"
* SHA, thanks to Jim Gillogly and an anonymous contributor for the information on
* what's changed in the new version. The fix is a simple change which involves
* adding a single rotate in the initial expansion function. It is unknown
* whether this is an optimal solution to the problem which was discovered in the
* SHA or whether it's simply a bandaid which fixes the problem with a minimum of
* effort (for example the reengineering of a great many Capstone chips).
*/
#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"
/* A block, treated as a sequence of 32-bit words. */
#define SHA1_DATA_LENGTH 16
/* SHA initial values */
#define h0init 0x67452301L
#define h1init 0xEFCDAB89L
#define h2init 0x98BADCFEL
#define h3init 0x10325476L
#define h4init 0xC3D2E1F0L
/* Initialize the SHA values */
void
sha1_init(struct sha1_ctx *ctx)
{
/* Set the h-vars to their initial values */
ctx->digest[ 0 ] = h0init;
ctx->digest[ 1 ] = h1init;
ctx->digest[ 2 ] = h2init;
ctx->digest[ 3 ] = h3init;
ctx->digest[ 4 ] = h4init;
/* Initialize bit count */
ctx->count_low = ctx->count_high = 0;
/* Initialize buffer */
ctx->index = 0;
}
#define SHA1_INCR(ctx) ((ctx)->count_high += !++(ctx)->count_low)
void
sha1_update(struct sha1_ctx *ctx,
unsigned length, const uint8_t *buffer)
{
if (ctx->index)
{ /* Try to fill partial block */
unsigned left = SHA1_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_sha1_compress(ctx->digest, ctx->block);
SHA1_INCR(ctx);
buffer += left;
length -= left;
}
}
while (length >= SHA1_DATA_SIZE)
{
_nettle_sha1_compress(ctx->digest, buffer);
SHA1_INCR(ctx);
buffer += SHA1_DATA_SIZE;
length -= SHA1_DATA_SIZE;
}
if ((ctx->index = length)) /* This assignment is intended */
/* Buffer leftovers */
memcpy(ctx->block, buffer, 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
sha1_final(struct sha1_ctx *ctx)
{
uint32_t bitcount_high;
uint32_t bitcount_low;
unsigned 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 < SHA1_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, SHA1_DATA_SIZE - i);
_nettle_sha1_compress(ctx->digest, ctx->block);
i = 0;
}
if (i < (SHA1_DATA_SIZE - 8))
memset(ctx->block + i, 0, (SHA1_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 + (SHA1_DATA_SIZE - 8), bitcount_high);
WRITE_UINT32(ctx->block + (SHA1_DATA_SIZE - 4), bitcount_low);
_nettle_sha1_compress(ctx->digest, ctx->block);
}
void
sha1_digest(struct sha1_ctx *ctx,
unsigned length,
uint8_t *digest)
{
assert(length <= SHA1_DIGEST_SIZE);
sha1_final(ctx);
_nettle_write_be32(length, digest, ctx->digest);
sha1_init(ctx);
}
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