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/* umac32.c
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2013 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., 51 Franklin Street, Fifth Floor, Boston,
* MA 02111-1301, USA.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include <string.h>
#include "umac.h"
#include "macros.h"
void
umac32_set_key (struct umac32_ctx *ctx, const uint8_t *key)
{
_umac_set_key (ctx->l1_key, ctx->l2_key, ctx->l3_key1, ctx->l3_key2,
&ctx->pdf_key, key, 1);
/* Clear nonce */
memset (ctx->nonce, 0, sizeof(ctx->nonce));
ctx->nonce_low = 0;
ctx->nonce_length = sizeof(ctx->nonce);
/* Initialize buffer */
ctx->count = ctx->index = 0;
}
void
umac32_set_nonce (struct umac32_ctx *ctx,
unsigned nonce_length, const uint8_t *nonce)
{
assert (nonce_length > 0);
assert (nonce_length <= AES_BLOCK_SIZE);
memcpy (ctx->nonce, nonce, nonce_length);
memset (ctx->nonce + nonce_length, 0, AES_BLOCK_SIZE - nonce_length);
ctx->nonce_low = ctx->nonce[nonce_length - 1] & 3;
ctx->nonce[nonce_length - 1] &= ~3;
ctx->nonce_length = nonce_length;
}
#define UMAC32_BLOCK(ctx, block) do { \
uint64_t __umac32_y \
= _umac_nh (ctx->l1_key, UMAC_BLOCK_SIZE, block) \
+ 8*UMAC_BLOCK_SIZE ; \
_umac_l2 (ctx->l2_key, ctx->l2_state, 1, ctx->count++, &__umac32_y); \
} while (0)
void
umac32_update (struct umac32_ctx *ctx,
unsigned length, const uint8_t *data)
{
MD_UPDATE (ctx, length, data, UMAC32_BLOCK, (void)0);
}
void
umac32_digest (struct umac32_ctx *ctx,
unsigned length, uint8_t *digest)
{
uint32_t pad;
assert (length > 0);
assert (length <= 4);
if (ctx->index > 0 || ctx->count == 0)
{
/* Zero pad to multiple of 32 */
uint64_t y;
unsigned pad = (ctx->index > 0) ? 31 & - ctx->index : 32;
memset (ctx->block + ctx->index, 0, pad);
y = _umac_nh (ctx->l1_key, ctx->index + pad, ctx->block)
+ 8 * ctx->index;
_umac_l2 (ctx->l2_key, ctx->l2_state, 1, ctx->count++, &y);
}
assert (ctx->count > 0);
if ( !(ctx->nonce_low & _UMAC_NONCE_CACHED))
{
aes_encrypt (&ctx->pdf_key, AES_BLOCK_SIZE,
(uint8_t *) ctx->pad_cache, ctx->nonce);
ctx->nonce_low |= _UMAC_NONCE_CACHED;
}
pad = ctx->pad_cache[ctx->nonce_low & 3];
/* Increment nonce */
ctx->nonce_low++;
if ( !(ctx->nonce_low & 3))
{
unsigned i = ctx->nonce_length - 1;
ctx->nonce_low = 0;
ctx->nonce[i] += 4;
if (ctx->nonce[i] == 0 && i > 0)
INCREMENT (i, ctx->nonce);
}
_umac_l2_final (ctx->l2_key, ctx->l2_state, 1, ctx->count);
pad ^= ctx->l3_key2[0] ^ _umac_l3 (ctx->l3_key1, ctx->l2_state);
memcpy (digest, &pad, length);
/* Reinitialize */
ctx->count = ctx->index = 0;
}
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