1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/security/nss/lib/freebl/ecl/ecp_mont.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,155 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.6 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +/* Uses Montgomery reduction for field arithmetic. See mpi/mpmontg.c for
1.9 + * code implementation. */
1.10 +
1.11 +#include "mpi.h"
1.12 +#include "mplogic.h"
1.13 +#include "mpi-priv.h"
1.14 +#include "ecl-priv.h"
1.15 +#include "ecp.h"
1.16 +#include <stdlib.h>
1.17 +#include <stdio.h>
1.18 +
1.19 +/* Construct a generic GFMethod for arithmetic over prime fields with
1.20 + * irreducible irr. */
1.21 +GFMethod *
1.22 +GFMethod_consGFp_mont(const mp_int *irr)
1.23 +{
1.24 + mp_err res = MP_OKAY;
1.25 + GFMethod *meth = NULL;
1.26 + mp_mont_modulus *mmm;
1.27 +
1.28 + meth = GFMethod_consGFp(irr);
1.29 + if (meth == NULL)
1.30 + return NULL;
1.31 +
1.32 + mmm = (mp_mont_modulus *) malloc(sizeof(mp_mont_modulus));
1.33 + if (mmm == NULL) {
1.34 + res = MP_MEM;
1.35 + goto CLEANUP;
1.36 + }
1.37 +
1.38 + meth->field_mul = &ec_GFp_mul_mont;
1.39 + meth->field_sqr = &ec_GFp_sqr_mont;
1.40 + meth->field_div = &ec_GFp_div_mont;
1.41 + meth->field_enc = &ec_GFp_enc_mont;
1.42 + meth->field_dec = &ec_GFp_dec_mont;
1.43 + meth->extra1 = mmm;
1.44 + meth->extra2 = NULL;
1.45 + meth->extra_free = &ec_GFp_extra_free_mont;
1.46 +
1.47 + mmm->N = meth->irr;
1.48 + mmm->n0prime = 0 - s_mp_invmod_radix(MP_DIGIT(&meth->irr, 0));
1.49 +
1.50 + CLEANUP:
1.51 + if (res != MP_OKAY) {
1.52 + GFMethod_free(meth);
1.53 + return NULL;
1.54 + }
1.55 + return meth;
1.56 +}
1.57 +
1.58 +/* Wrapper functions for generic prime field arithmetic. */
1.59 +
1.60 +/* Field multiplication using Montgomery reduction. */
1.61 +mp_err
1.62 +ec_GFp_mul_mont(const mp_int *a, const mp_int *b, mp_int *r,
1.63 + const GFMethod *meth)
1.64 +{
1.65 + mp_err res = MP_OKAY;
1.66 +
1.67 +#ifdef MP_MONT_USE_MP_MUL
1.68 + /* if MP_MONT_USE_MP_MUL is defined, then the function s_mp_mul_mont
1.69 + * is not implemented and we have to use mp_mul and s_mp_redc directly
1.70 + */
1.71 + MP_CHECKOK(mp_mul(a, b, r));
1.72 + MP_CHECKOK(s_mp_redc(r, (mp_mont_modulus *) meth->extra1));
1.73 +#else
1.74 + mp_int s;
1.75 +
1.76 + MP_DIGITS(&s) = 0;
1.77 + /* s_mp_mul_mont doesn't allow source and destination to be the same */
1.78 + if ((a == r) || (b == r)) {
1.79 + MP_CHECKOK(mp_init(&s));
1.80 + MP_CHECKOK(s_mp_mul_mont
1.81 + (a, b, &s, (mp_mont_modulus *) meth->extra1));
1.82 + MP_CHECKOK(mp_copy(&s, r));
1.83 + mp_clear(&s);
1.84 + } else {
1.85 + return s_mp_mul_mont(a, b, r, (mp_mont_modulus *) meth->extra1);
1.86 + }
1.87 +#endif
1.88 + CLEANUP:
1.89 + return res;
1.90 +}
1.91 +
1.92 +/* Field squaring using Montgomery reduction. */
1.93 +mp_err
1.94 +ec_GFp_sqr_mont(const mp_int *a, mp_int *r, const GFMethod *meth)
1.95 +{
1.96 + return ec_GFp_mul_mont(a, a, r, meth);
1.97 +}
1.98 +
1.99 +/* Field division using Montgomery reduction. */
1.100 +mp_err
1.101 +ec_GFp_div_mont(const mp_int *a, const mp_int *b, mp_int *r,
1.102 + const GFMethod *meth)
1.103 +{
1.104 + mp_err res = MP_OKAY;
1.105 +
1.106 + /* if A=aZ represents a encoded in montgomery coordinates with Z and #
1.107 + * and \ respectively represent multiplication and division in
1.108 + * montgomery coordinates, then A\B = (a/b)Z = (A/B)Z and Binv =
1.109 + * (1/b)Z = (1/B)(Z^2) where B # Binv = Z */
1.110 + MP_CHECKOK(ec_GFp_div(a, b, r, meth));
1.111 + MP_CHECKOK(ec_GFp_enc_mont(r, r, meth));
1.112 + if (a == NULL) {
1.113 + MP_CHECKOK(ec_GFp_enc_mont(r, r, meth));
1.114 + }
1.115 + CLEANUP:
1.116 + return res;
1.117 +}
1.118 +
1.119 +/* Encode a field element in Montgomery form. See s_mp_to_mont in
1.120 + * mpi/mpmontg.c */
1.121 +mp_err
1.122 +ec_GFp_enc_mont(const mp_int *a, mp_int *r, const GFMethod *meth)
1.123 +{
1.124 + mp_mont_modulus *mmm;
1.125 + mp_err res = MP_OKAY;
1.126 +
1.127 + mmm = (mp_mont_modulus *) meth->extra1;
1.128 + MP_CHECKOK(mp_copy(a, r));
1.129 + MP_CHECKOK(s_mp_lshd(r, MP_USED(&mmm->N)));
1.130 + MP_CHECKOK(mp_mod(r, &mmm->N, r));
1.131 + CLEANUP:
1.132 + return res;
1.133 +}
1.134 +
1.135 +/* Decode a field element from Montgomery form. */
1.136 +mp_err
1.137 +ec_GFp_dec_mont(const mp_int *a, mp_int *r, const GFMethod *meth)
1.138 +{
1.139 + mp_err res = MP_OKAY;
1.140 +
1.141 + if (a != r) {
1.142 + MP_CHECKOK(mp_copy(a, r));
1.143 + }
1.144 + MP_CHECKOK(s_mp_redc(r, (mp_mont_modulus *) meth->extra1));
1.145 + CLEANUP:
1.146 + return res;
1.147 +}
1.148 +
1.149 +/* Free the memory allocated to the extra fields of Montgomery GFMethod
1.150 + * object. */
1.151 +void
1.152 +ec_GFp_extra_free_mont(GFMethod *meth)
1.153 +{
1.154 + if (meth->extra1 != NULL) {
1.155 + free(meth->extra1);
1.156 + meth->extra1 = NULL;
1.157 + }
1.158 +}
