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/* md5.c
*
* The MD5 hash function, described in RFC 1321.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001 Niels Mller
*
* 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.
*/
/* Based on public domain code hacked by Colin Plumb, Andrew Kuchling, and
* Niels Mller. */
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include <string.h>
#include "md5.h"
#include "macros.h"
static void
md5_final(struct md5_ctx *ctx);
void
md5_init(struct md5_ctx *ctx)
{
ctx->digest[0] = 0x67452301;
ctx->digest[1] = 0xefcdab89;
ctx->digest[2] = 0x98badcfe;
ctx->digest[3] = 0x10325476;
ctx->count_l = ctx->count_h = 0;
ctx->index = 0;
}
#define MD5_INCR(ctx) ((ctx)->count_h += !++(ctx)->count_l)
void
md5_update(struct md5_ctx *ctx,
unsigned length,
const uint8_t *data)
{
if (ctx->index)
{
/* Try to fill partial block */
unsigned left = MD5_DATA_SIZE - ctx->index;
if (length < left)
{
memcpy(ctx->block + ctx->index, data, length);
ctx->index += length;
return; /* Finished */
}
else
{
memcpy(ctx->block + ctx->index, data, left);
_nettle_md5_compress(ctx->digest, ctx->block);
MD5_INCR(ctx);
data += left;
length -= left;
}
}
while (length >= MD5_DATA_SIZE)
{
_nettle_md5_compress(ctx->digest, data);
MD5_INCR(ctx);
data += MD5_DATA_SIZE;
length -= MD5_DATA_SIZE;
}
if ((ctx->index = length)) /* This assignment is intended */
/* Buffer leftovers */
memcpy(ctx->block, data, length);
}
void
md5_digest(struct md5_ctx *ctx,
unsigned length,
uint8_t *digest)
{
unsigned i;
unsigned words;
unsigned leftover;
assert(length <= MD5_DIGEST_SIZE);
md5_final(ctx);
words = length / 4;
leftover = length % 4;
/* Little endian order */
for (i = 0; i < words; i++, digest += 4)
LE_WRITE_UINT32(digest, ctx->digest[i]);
if (leftover)
{
uint32_t word;
unsigned j;
assert(i < _MD5_DIGEST_LENGTH);
/* Still least significant byte first. */
for (word = ctx->digest[i], j = 0; j < leftover;
j++, word >>= 8)
digest[j] = word & 0xff;
}
md5_init(ctx);
}
/* Final wrapup - pad to MD5_DATA_SIZE-byte boundary with the bit
* pattern 1 0* (64-bit count of bits processed, LSB-first) */
static void
md5_final(struct md5_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 < MD5_DATA_SIZE);
ctx->block[i++] = 0x80;
if (i > (MD5_DATA_SIZE - 8))
{
/* No room for length in this block. Process it and
pad with another one */
memset(ctx->block + i, 0, MD5_DATA_SIZE - i);
_nettle_md5_compress(ctx->digest, ctx->block);
i = 0;
}
if (i < (MD5_DATA_SIZE - 8))
memset(ctx->block + i, 0, (MD5_DATA_SIZE - 8) - i);
/* There are 512 = 2^9 bits in one block
* Little-endian order => Least significant word first */
bitcount_low = (ctx->count_l << 9) | (ctx->index << 3);
bitcount_high = (ctx->count_h << 9) | (ctx->count_l >> 23);
LE_WRITE_UINT32(ctx->block + (MD5_DATA_SIZE - 8), bitcount_low);
LE_WRITE_UINT32(ctx->block + (MD5_DATA_SIZE - 4), bitcount_high);
_nettle_md5_compress(ctx->digest, ctx->block);
}
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