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/* umac-l2.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"
/* Same mask applied to low and high halves */
#define KEY_MASK 0x01ffffffUL
#if WORDS_BIGENDIAN
#define BE_SWAP32(x) x
#else
#define BE_SWAP32(x) \
((ROTL32(8, x) & 0x00FF00FFUL) | \
(ROTL32(24, x) & 0xFF00FF00UL))
#endif
void
_umac_l2_init (unsigned size, uint32_t *k)
{
unsigned i;
for (i = 0; i < size; i++)
{
uint32_t w = k[i];
w = BE_SWAP32 (w);
k[i] = w & KEY_MASK;
}
}
void
_umac_l2(const uint32_t *key, uint64_t *state, unsigned n,
uint64_t count, const uint64_t *m)
{
uint64_t *prev = state + 2*n;
unsigned i;
if (count == 0)
memcpy (prev, m, n * sizeof(*m));
else if (count == 1)
for (i = 0; i < n; i++, key += 6)
{
uint64_t y = _umac_poly64 (key[0], key[1], 1, prev[i]);
state[2*i+1] = _umac_poly64 (key[0], key[1], y, m[i]);
}
else if (count < UMAC_POLY64_BLOCKS)
for (i = 0; i < n; i++, key += 6)
state[2*i+1] = _umac_poly64 (key[0], key[1], state[2*i+1], m[i]);
else if (count % 2 == 0)
{
if (count == UMAC_POLY64_BLOCKS)
for (i = 0, key += 2; i < n; i++, key += 6)
{
uint64_t y = state[2*i+1];
if (y >= UMAC_P64)
y -= UMAC_P64;
state[2*i] = 0;
state[2*i+1] = 1;
_umac_poly128 (key, state + 2*i, 0, y);
}
memcpy (prev, m, n * sizeof(*m));
}
else
for (i = 0, key += 2; i < n; i++, key += 6)
_umac_poly128 (key, state + 2*i, prev[i], m[i]);
}
void
_umac_l2_final(const uint32_t *key, uint64_t *state, unsigned n,
uint64_t count)
{
uint64_t *prev = state + 2*n;
unsigned i;
assert (count > 0);
if (count == 1)
for (i = 0; i < n; i++)
{
*state++ = 0;
*state++ = *prev++;
}
else if (count <= UMAC_POLY64_BLOCKS)
for (i = 0; i < n; i++)
{
uint64_t y;
*state++ = 0;
y = *state;
if (y >= UMAC_P64)
y -= UMAC_P64;
*state++ = y;
}
else
{
uint64_t pad = (uint64_t) 1 << 63;
if (count % 2 == 1)
for (i = 0, key += 2; i < n; i++, key += 6)
_umac_poly128 (key, state + 2*i, prev[i], pad);
else
for (i = 0, key += 2; i < n; i++, key += 6)
_umac_poly128 (key, state + 2*i, pad, 0);
for (i = 0; i < n; i++, state += 2)
{
uint64_t yh, yl;
yh = state[0];
yl = state[1];
if (yh == UMAC_P128_HI && yl >= UMAC_P128_LO)
{
state[0] = 0;
state[1] = yl -= UMAC_P128_LO;
}
}
}
}
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