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/* umac-l3.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 "umac.h"
#include "macros.h"
/* 2^36 - 5 */
#define P 0x0000000FFFFFFFFBULL
#if WORDS_BIGENDIAN
#define BE_SWAP64(x) x
#else
#define BE_SWAP64(x) \
(((x & 0xff) << 56) \
| ((x & 0xff00) << 40) \
| ((x & 0xff0000) << 24) \
| ((x & 0xff000000) << 8) \
| ((x >> 8) & 0xff000000) \
| ((x >> 24) & 0xff0000) \
| ((x >> 40) & 0xff00) \
| (x >> 56) )
#endif
void
_umac_l3_init (unsigned size, uint64_t *k)
{
unsigned i;
for (i = 0; i < size; i++)
{
uint64_t w = k[i];
w = BE_SWAP64 (w);
k[i] = w % P;
}
}
static uint64_t
umac_l3_word (const uint64_t *k, uint64_t w)
{
unsigned i;
uint64_t y;
/* Since it's easiest to process the input word from the low end,
* loop over keys in reverse order. */
for (i = y = 0; i < 4; i++, w >>= 16)
y += (w & 0xffff) * k[3-i];
return y;
}
uint32_t
_umac_l3 (const uint64_t *key, const uint64_t *m)
{
uint32_t y = (umac_l3_word (key, m[0])
+ umac_l3_word (key + 4, m[1])) % P;
#if !WORDS_BIGENDIAN
y = ((ROTL32(8, y) & 0x00FF00FFUL)
| (ROTL32(24, y) & 0xFF00FF00UL));
#endif
return y;
}
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