ecc-384.c 4.74 KB
Newer Older
1
/* ecc-384.c
2 3 4

   Compile time constant (but machine dependent) tables.

5
   Copyright (C) 2013, 2014 Niels Möller
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

   This file is part of GNU Nettle.

   GNU Nettle is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.

   GNU Nettle 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
   General Public License for more details.

   You should have received copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see http://www.gnu.org/licenses/.
*/
Niels Möller's avatar
Niels Möller committed
33

34
/* Development of Nettle's ECC support was funded by the .SE Internet Fund. */
Niels Möller's avatar
Niels Möller committed
35 36 37 38 39 40 41

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <assert.h>

42
#include "ecc.h"
Niels Möller's avatar
Niels Möller committed
43 44 45 46 47 48
#include "ecc-internal.h"

#define USE_REDC 0

#include "ecc-384.h"

Niels Möller's avatar
Niels Möller committed
49 50 51
#if HAVE_NATIVE_ecc_384_modp
#define ecc_384_modp nettle_ecc_384_modp
void
52
ecc_384_modp (const struct ecc_modulo *m, mp_limb_t *rp);
Niels Möller's avatar
Niels Möller committed
53 54
#elif GMP_NUMB_BITS == 32

Niels Möller's avatar
Niels Möller committed
55 56 57 58 59 60 61 62 63 64
/* Use that 2^{384} = 2^{128} + 2^{96} - 2^{32} + 1, and eliminate 256
   bits at a time.

   We can get carry == 2 in the first iteration, and I think *only* in
   the first iteration. */

/* p is 12 limbs, and B^12 - p = B^4 + B^3 - B + 1. We can eliminate
   almost 8 at a time. Do only 7, to avoid additional carry
   propagation, followed by 5. */
static void
65
ecc_384_modp (const struct ecc_modulo *p, mp_limb_t *rp)
Niels Möller's avatar
Niels Möller committed
66 67 68 69 70 71 72 73
{
  mp_limb_t cy, bw;

  /* Reduce from 24 to 17 limbs. */
  cy = mpn_add_n (rp + 4, rp + 4, rp + 16, 8);
  cy = sec_add_1 (rp + 12, rp + 12, 3, cy);

  bw = mpn_sub_n (rp + 5, rp + 5, rp + 16, 8);
74
  bw = sec_sub_1 (rp + 13, rp + 13, 3, bw);
Niels Möller's avatar
Niels Möller committed
75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90

  cy += mpn_add_n (rp + 7, rp + 7, rp + 16, 8);
  cy = sec_add_1 (rp + 15, rp + 15, 1, cy);

  cy += mpn_add_n (rp + 8, rp + 8, rp + 16, 8);
  assert (bw <= cy);
  cy -= bw;

  assert (cy <= 2);  
  rp[16] = cy;

  /* Reduce from 17 to 12 limbs */
  cy = mpn_add_n (rp, rp, rp + 12, 5);
  cy = sec_add_1 (rp + 5, rp + 5, 3, cy);
  
  bw = mpn_sub_n (rp + 1, rp + 1, rp + 12, 5);
91
  bw = sec_sub_1 (rp + 6, rp + 6, 6, bw);
Niels Möller's avatar
Niels Möller committed
92 93 94 95 96 97 98 99 100 101
  
  cy += mpn_add_n (rp + 3, rp + 3, rp + 12, 5);
  cy = sec_add_1 (rp + 8, rp + 8, 1, cy);

  cy += mpn_add_n (rp + 4, rp + 4, rp + 12, 5);
  cy = sec_add_1 (rp + 9, rp + 9, 3, cy);

  assert (cy >= bw);
  cy -= bw;
  assert (cy <= 1);
102
  cy = cnd_add_n (cy, rp, p->B, ECC_LIMB_SIZE);
Niels Möller's avatar
Niels Möller committed
103 104 105 106 107 108
  assert (cy == 0);
}
#elif GMP_NUMB_BITS == 64
/* p is 6 limbs, and B^6 - p = B^2 + 2^32 (B - 1) + 1. Eliminate 3
   (almost 4) limbs at a time. */
static void
109
ecc_384_modp (const struct ecc_modulo *p, mp_limb_t *rp)
Niels Möller's avatar
Niels Möller committed
110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131
{
  mp_limb_t tp[6];
  mp_limb_t cy;

  /* Reduce from 12 to 9 limbs */
  tp[0] = 0; /* FIXME: Could use mpn_sub_nc */
  mpn_copyi (tp + 1, rp + 8, 3);
  tp[4] = rp[11] - mpn_sub_n (tp, tp, rp + 8, 4);
  tp[5] = mpn_lshift (tp, tp, 5, 32);

  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 + 2, rp + 2, tp, 6);
  cy += mpn_add_n (rp + 4, rp + 4, rp + 8, 4);

  assert (cy <= 2);
  rp[8] = cy;

  /* Reduce from 9 to 6 limbs */
  tp[0] = 0;
  mpn_copyi (tp + 1, rp + 6, 2);
132
  tp[3] = rp[8] - mpn_sub_n (tp, tp, rp + 6, 3);
Niels Möller's avatar
Niels Möller committed
133 134 135 136 137 138 139 140 141 142
  tp[4] = mpn_lshift (tp, tp, 4, 32);

  cy = mpn_add_n (rp, rp, rp + 6, 3);
  cy = sec_add_1 (rp + 3, rp + 3, 2, cy);
  cy += mpn_add_n (rp, rp, tp, 5);
  cy += mpn_add_n (rp + 2, rp + 2, rp + 6, 3);

  cy = sec_add_1 (rp + 5, rp + 5, 1, cy);
  assert (cy <= 1);

143
  cy = cnd_add_n (cy, rp, p->B, ECC_LIMB_SIZE);
Niels Möller's avatar
Niels Möller committed
144 145 146
  assert (cy == 0);  
}
#else
147
#define ecc_384_modp ecc_mod
Niels Möller's avatar
Niels Möller committed
148 149 150 151
#endif
  
const struct ecc_curve nettle_secp_384r1 =
{
Niels Möller's avatar
Niels Möller committed
152 153 154 155 156
  {
    384,
    ECC_LIMB_SIZE,    
    ECC_BMODP_SIZE,
    ECC_REDC_SIZE,
157 158
    ECC_MOD_INV_ITCH (ECC_LIMB_SIZE),

Niels Möller's avatar
Niels Möller committed
159 160 161 162
    ecc_p,
    ecc_Bmodp,
    ecc_Bmodp_shifted,
    ecc_redc_ppm1,
163 164
    ecc_pp1h,

165 166
    ecc_384_modp,
    ecc_384_modp,
167
    ecc_mod_inv,
Niels Möller's avatar
Niels Möller committed
168 169 170 171 172 173
  },
  {
    384,
    ECC_LIMB_SIZE,    
    ECC_BMODQ_SIZE,
    0,
174 175
    ECC_MOD_INV_ITCH (ECC_LIMB_SIZE),

Niels Möller's avatar
Niels Möller committed
176 177 178 179
    ecc_q,
    ecc_Bmodq,
    ecc_Bmodq_shifted,
    NULL,
180 181
    ecc_qp1h,

182 183
    ecc_mod,
    ecc_mod,
184
    ecc_mod_inv,
Niels Möller's avatar
Niels Möller committed
185 186
  },

Niels Möller's avatar
Niels Möller committed
187 188 189
  USE_REDC,
  ECC_PIPPENGER_K,
  ECC_PIPPENGER_C,
190

191
  ECC_ADD_JJJ_ITCH (ECC_LIMB_SIZE),
192 193 194 195
  ECC_MUL_A_ITCH (ECC_LIMB_SIZE),
  ECC_MUL_G_ITCH (ECC_LIMB_SIZE),
  ECC_J_TO_A_ITCH (ECC_LIMB_SIZE),

196
  ecc_add_jjj,
197 198 199 200
  ecc_mul_a,
  ecc_mul_g,
  ecc_j_to_a,

Niels Möller's avatar
Niels Möller committed
201 202
  ecc_b,
  ecc_g,
203
  NULL,
Niels Möller's avatar
Niels Möller committed
204 205 206
  ecc_unit,
  ecc_table
};