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/* umac96.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
umac96_set_key (struct umac96_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, 3);
/* Clear nonce */
memset (ctx->nonce, 0, sizeof(ctx->nonce));
ctx->nonce_length = sizeof(ctx->nonce);
/* Initialize buffer */
ctx->count = ctx->index = 0;
}
void
umac96_set_nonce (struct umac96_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_length = nonce_length;
}
#define UMAC96_BLOCK(ctx, block) do { \
uint64_t __umac96_y[3]; \
_umac_nh_n (__umac96_y, 3, ctx->l1_key, UMAC_DATA_SIZE, block); \
__umac96_y[0] += 8*UMAC_DATA_SIZE; \
__umac96_y[1] += 8*UMAC_DATA_SIZE; \
__umac96_y[2] += 8*UMAC_DATA_SIZE; \
_umac_l2 (ctx->l2_key, ctx->l2_state, 3, ctx->count++, __umac96_y); \
} while (0)
void
umac96_update (struct umac96_ctx *ctx,
unsigned length, const uint8_t *data)
{
MD_UPDATE (ctx, length, data, UMAC96_BLOCK, (void)0);
}
void
umac96_digest (struct umac96_ctx *ctx,
unsigned length, uint8_t *digest)
{
uint32_t tag[4];
unsigned i;
assert (length > 0);
assert (length <= 12);
if (ctx->index > 0 || ctx->count == 0)
{
/* Zero pad to multiple of 32 */
uint64_t y[3];
unsigned pad = (ctx->index > 0) ? 31 & - ctx->index : 32;
memset (ctx->block + ctx->index, 0, pad);
_umac_nh_n (y, 3, ctx->l1_key, ctx->index + pad, ctx->block);
y[0] += 8 * ctx->index;
y[1] += 8 * ctx->index;
y[2] += 8 * ctx->index;
_umac_l2 (ctx->l2_key, ctx->l2_state, 3, ctx->count++, y);
}
assert (ctx->count > 0);
aes_encrypt (&ctx->pdf_key, AES_BLOCK_SIZE,
(uint8_t *) tag, ctx->nonce);
INCREMENT (ctx->nonce_length, ctx->nonce);
_umac_l2_final (ctx->l2_key, ctx->l2_state, 3, ctx->count);
for (i = 0; i < 3; i++)
tag[i] ^= ctx->l3_key2[i] ^ _umac_l3 (ctx->l3_key1 + 8*i,
ctx->l2_state + 2*i);
memcpy (digest, tag, length);
/* Reinitialize */
ctx->count = ctx->index = 0;
}
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