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/* ecc-192.c */
/* Compile time constant (but machine dependent) tables. */
/* 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.
*/
/* Development of Nettle's ECC support was funded by the .SE Internet Fund. */
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include "ecc-internal.h"
#define USE_REDC 0
#include "ecc-192.h"
#if HAVE_NATIVE_ecc_192_modp
#define ecc_192_modp nettle_ecc_192_modp
void
ecc_192_modp (const struct ecc_curve *ecc, mp_limb_t *rp);
/* Use that p = 2^{192} - 2^64 - 1, to eliminate 128 bits at a time. */
#elif GMP_NUMB_BITS == 32
/* p is 6 limbs, p = B^6 - B^2 - 1 */
static void
ecc_192_modp (const struct ecc_curve *ecc UNUSED, mp_limb_t *rp)
{
mp_limb_t cy;
/* Reduce from 12 to 9 limbs (top limb small)*/
cy = mpn_add_n (rp + 2, rp + 2, rp + 8, 4);
cy = sec_add_1 (rp + 6, rp + 6, 2, cy);
cy += mpn_add_n (rp + 4, rp + 4, rp + 8, 4);
assert (cy <= 2);
rp[8] = cy;
/* Reduce from 9 to 6 limbs */
cy = mpn_add_n (rp, rp, rp + 6, 3);
cy = sec_add_1 (rp + 3, rp + 3, 2, cy);
cy += mpn_add_n (rp + 2, rp + 2, rp + 6, 3);
cy = sec_add_1 (rp + 5, rp + 5, 1, cy);
assert (cy <= 1);
cy = cnd_add_n (cy, rp, ecc_Bmodp, 6);
assert (cy == 0);
}
#elif GMP_NUMB_BITS == 64
/* p is 3 limbs, p = B^3 - B - 1 */
static void
ecc_192_modp (const struct ecc_curve *ecc UNUSED, mp_limb_t *rp)
{
mp_limb_t cy;
/* Reduce from 6 to 5 limbs (top limb small)*/
cy = mpn_add_n (rp + 1, rp + 1, rp + 4, 2);
cy = sec_add_1 (rp + 3, rp + 3, 1, cy);
cy += mpn_add_n (rp + 2, rp + 2, rp + 4, 2);
assert (cy <= 2);
rp[4] = cy;
/* Reduce from 5 to 4 limbs (high limb small) */
cy = mpn_add_n (rp, rp, rp + 3, 2);
cy = sec_add_1 (rp + 2, rp + 2, 1, cy);
cy += mpn_add_n (rp + 1, rp + 1, rp + 3, 2);
assert (cy <= 1);
cy = cnd_add_n (cy, rp, ecc_Bmodp, 3);
assert (cy == 0);
}
#else
#define ecc_192_modp ecc_generic_modp
#endif
const struct ecc_curve nettle_secp_192r1 =
{
192,
ECC_LIMB_SIZE,
ECC_BMODP_SIZE,
ECC_BMODQ_SIZE,
USE_REDC,
ECC_REDC_SIZE,
ECC_PIPPENGER_K,
ECC_PIPPENGER_C,
ecc_p,
ecc_b,
ecc_q,
ecc_g,
ecc_redc_g,
ecc_192_modp,
ecc_generic_redc,
ecc_192_modp,
ecc_generic_modq,
ecc_Bmodp,
ecc_Bmodp_shifted,
ecc_pp1h,
ecc_redc_ppm1,
ecc_unit,
ecc_Bmodq,
ecc_Bmodq_shifted,
ecc_qp1h,
ecc_table
};
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