3 /* Compile time constant (but machine dependent) tables. */
5 /* nettle, low-level cryptographics library
7 * Copyright (C) 2013 Niels Möller
9 * The nettle library is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU Lesser General Public License as published by
11 * the Free Software Foundation; either version 2.1 of the License, or (at your
12 * option) any later version.
14 * The nettle library is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17 * License for more details.
19 * You should have received a copy of the GNU Lesser General Public License
20 * along with the nettle library; see the file COPYING.LIB. If not, write to
21 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
25 /* Development of Nettle's ECC support was funded by the .SE Internet Fund. */
33 #include "ecc-internal.h"
39 #if HAVE_NATIVE_ecc_384_modp
40 #define ecc_384_modp nettle_ecc_384_modp
42 ecc_384_modp (const struct ecc_curve *ecc, mp_limb_t *rp);
43 #elif GMP_NUMB_BITS == 32
45 /* Use that 2^{384} = 2^{128} + 2^{96} - 2^{32} + 1, and eliminate 256
48 We can get carry == 2 in the first iteration, and I think *only* in
49 the first iteration. */
51 /* p is 12 limbs, and B^12 - p = B^4 + B^3 - B + 1. We can eliminate
52 almost 8 at a time. Do only 7, to avoid additional carry
53 propagation, followed by 5. */
55 ecc_384_modp (const struct ecc_curve *ecc, mp_limb_t *rp)
59 /* Reduce from 24 to 17 limbs. */
60 cy = mpn_add_n (rp + 4, rp + 4, rp + 16, 8);
61 cy = sec_add_1 (rp + 12, rp + 12, 3, cy);
63 bw = mpn_sub_n (rp + 5, rp + 5, rp + 16, 8);
64 bw = sec_sub_1 (rp + 13, rp + 13, 3, bw);
66 cy += mpn_add_n (rp + 7, rp + 7, rp + 16, 8);
67 cy = sec_add_1 (rp + 15, rp + 15, 1, cy);
69 cy += mpn_add_n (rp + 8, rp + 8, rp + 16, 8);
76 /* Reduce from 17 to 12 limbs */
77 cy = mpn_add_n (rp, rp, rp + 12, 5);
78 cy = sec_add_1 (rp + 5, rp + 5, 3, cy);
80 bw = mpn_sub_n (rp + 1, rp + 1, rp + 12, 5);
81 bw = sec_sub_1 (rp + 6, rp + 6, 6, bw);
83 cy += mpn_add_n (rp + 3, rp + 3, rp + 12, 5);
84 cy = sec_add_1 (rp + 8, rp + 8, 1, cy);
86 cy += mpn_add_n (rp + 4, rp + 4, rp + 12, 5);
87 cy = sec_add_1 (rp + 9, rp + 9, 3, cy);
92 cy = cnd_add_n (cy, rp, ecc->Bmodp, ECC_LIMB_SIZE);
95 #elif GMP_NUMB_BITS == 64
96 /* p is 6 limbs, and B^6 - p = B^2 + 2^32 (B - 1) + 1. Eliminate 3
97 (almost 4) limbs at a time. */
99 ecc_384_modp (const struct ecc_curve *ecc, mp_limb_t *rp)
104 /* Reduce from 12 to 9 limbs */
105 tp[0] = 0; /* FIXME: Could use mpn_sub_nc */
106 mpn_copyi (tp + 1, rp + 8, 3);
107 tp[4] = rp[11] - mpn_sub_n (tp, tp, rp + 8, 4);
108 tp[5] = mpn_lshift (tp, tp, 5, 32);
110 cy = mpn_add_n (rp + 2, rp + 2, rp + 8, 4);
111 cy = sec_add_1 (rp + 6, rp + 6, 2, cy);
113 cy += mpn_add_n (rp + 2, rp + 2, tp, 6);
114 cy += mpn_add_n (rp + 4, rp + 4, rp + 8, 4);
119 /* Reduce from 9 to 6 limbs */
121 mpn_copyi (tp + 1, rp + 6, 2);
122 tp[3] = rp[8] - mpn_sub_n (tp, tp, rp + 6, 3);
123 tp[4] = mpn_lshift (tp, tp, 4, 32);
125 cy = mpn_add_n (rp, rp, rp + 6, 3);
126 cy = sec_add_1 (rp + 3, rp + 3, 2, cy);
127 cy += mpn_add_n (rp, rp, tp, 5);
128 cy += mpn_add_n (rp + 2, rp + 2, rp + 6, 3);
130 cy = sec_add_1 (rp + 5, rp + 5, 1, cy);
133 cy = cnd_add_n (cy, rp, ecc->Bmodp, ECC_LIMB_SIZE);
137 #define ecc_384_modp ecc_generic_modp
140 const struct ecc_curve nettle_secp_384r1 =
156 ECC_REDC_SIZE != 0 ? ecc_generic_redc : NULL,