~ubuntu-branches/ubuntu/wily/nettle/wily

/* 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

};