| Index: nss/lib/freebl/ecl/ecp_521.c
|
| ===================================================================
|
| --- nss/lib/freebl/ecl/ecp_521.c (revision 0)
|
| +++ nss/lib/freebl/ecl/ecp_521.c (revision 0)
|
| @@ -0,0 +1,137 @@
|
| +/* This Source Code Form is subject to the terms of the Mozilla Public
|
| + * License, v. 2.0. If a copy of the MPL was not distributed with this
|
| + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
| +
|
| +#include "ecp.h"
|
| +#include "mpi.h"
|
| +#include "mplogic.h"
|
| +#include "mpi-priv.h"
|
| +
|
| +#define ECP521_DIGITS ECL_CURVE_DIGITS(521)
|
| +
|
| +/* Fast modular reduction for p521 = 2^521 - 1. a can be r. Uses
|
| + * algorithm 2.31 from Hankerson, Menezes, Vanstone. Guide to
|
| + * Elliptic Curve Cryptography. */
|
| +static mp_err
|
| +ec_GFp_nistp521_mod(const mp_int *a, mp_int *r, const GFMethod *meth)
|
| +{
|
| + mp_err res = MP_OKAY;
|
| + int a_bits = mpl_significant_bits(a);
|
| + int i;
|
| +
|
| + /* m1, m2 are statically-allocated mp_int of exactly the size we need */
|
| + mp_int m1;
|
| +
|
| + mp_digit s1[ECP521_DIGITS] = { 0 };
|
| +
|
| + MP_SIGN(&m1) = MP_ZPOS;
|
| + MP_ALLOC(&m1) = ECP521_DIGITS;
|
| + MP_USED(&m1) = ECP521_DIGITS;
|
| + MP_DIGITS(&m1) = s1;
|
| +
|
| + if (a_bits < 521) {
|
| + if (a==r) return MP_OKAY;
|
| + return mp_copy(a, r);
|
| + }
|
| + /* for polynomials larger than twice the field size or polynomials
|
| + * not using all words, use regular reduction */
|
| + if (a_bits > (521*2)) {
|
| + MP_CHECKOK(mp_mod(a, &meth->irr, r));
|
| + } else {
|
| +#define FIRST_DIGIT (ECP521_DIGITS-1)
|
| + for (i = FIRST_DIGIT; i < MP_USED(a)-1; i++) {
|
| + s1[i-FIRST_DIGIT] = (MP_DIGIT(a, i) >> 9)
|
| + | (MP_DIGIT(a, 1+i) << (MP_DIGIT_BIT-9));
|
| + }
|
| + s1[i-FIRST_DIGIT] = MP_DIGIT(a, i) >> 9;
|
| +
|
| + if ( a != r ) {
|
| + MP_CHECKOK(s_mp_pad(r,ECP521_DIGITS));
|
| + for (i = 0; i < ECP521_DIGITS; i++) {
|
| + MP_DIGIT(r,i) = MP_DIGIT(a, i);
|
| + }
|
| + }
|
| + MP_USED(r) = ECP521_DIGITS;
|
| + MP_DIGIT(r,FIRST_DIGIT) &= 0x1FF;
|
| +
|
| + MP_CHECKOK(s_mp_add(r, &m1));
|
| + if (MP_DIGIT(r, FIRST_DIGIT) & 0x200) {
|
| + MP_CHECKOK(s_mp_add_d(r,1));
|
| + MP_DIGIT(r,FIRST_DIGIT) &= 0x1FF;
|
| + } else if (s_mp_cmp(r, &meth->irr) == 0) {
|
| + mp_zero(r);
|
| + }
|
| + s_mp_clamp(r);
|
| + }
|
| +
|
| + CLEANUP:
|
| + return res;
|
| +}
|
| +
|
| +/* Compute the square of polynomial a, reduce modulo p521. Store the
|
| + * result in r. r could be a. Uses optimized modular reduction for p521.
|
| + */
|
| +static mp_err
|
| +ec_GFp_nistp521_sqr(const mp_int *a, mp_int *r, const GFMethod *meth)
|
| +{
|
| + mp_err res = MP_OKAY;
|
| +
|
| + MP_CHECKOK(mp_sqr(a, r));
|
| + MP_CHECKOK(ec_GFp_nistp521_mod(r, r, meth));
|
| + CLEANUP:
|
| + return res;
|
| +}
|
| +
|
| +/* Compute the product of two polynomials a and b, reduce modulo p521.
|
| + * Store the result in r. r could be a or b; a could be b. Uses
|
| + * optimized modular reduction for p521. */
|
| +static mp_err
|
| +ec_GFp_nistp521_mul(const mp_int *a, const mp_int *b, mp_int *r,
|
| + const GFMethod *meth)
|
| +{
|
| + mp_err res = MP_OKAY;
|
| +
|
| + MP_CHECKOK(mp_mul(a, b, r));
|
| + MP_CHECKOK(ec_GFp_nistp521_mod(r, r, meth));
|
| + CLEANUP:
|
| + return res;
|
| +}
|
| +
|
| +/* Divides two field elements. If a is NULL, then returns the inverse of
|
| + * b. */
|
| +static mp_err
|
| +ec_GFp_nistp521_div(const mp_int *a, const mp_int *b, mp_int *r,
|
| + const GFMethod *meth)
|
| +{
|
| + mp_err res = MP_OKAY;
|
| + mp_int t;
|
| +
|
| + /* If a is NULL, then return the inverse of b, otherwise return a/b. */
|
| + if (a == NULL) {
|
| + return mp_invmod(b, &meth->irr, r);
|
| + } else {
|
| + /* MPI doesn't support divmod, so we implement it using invmod and
|
| + * mulmod. */
|
| + MP_CHECKOK(mp_init(&t));
|
| + MP_CHECKOK(mp_invmod(b, &meth->irr, &t));
|
| + MP_CHECKOK(mp_mul(a, &t, r));
|
| + MP_CHECKOK(ec_GFp_nistp521_mod(r, r, meth));
|
| + CLEANUP:
|
| + mp_clear(&t);
|
| + return res;
|
| + }
|
| +}
|
| +
|
| +/* Wire in fast field arithmetic and precomputation of base point for
|
| + * named curves. */
|
| +mp_err
|
| +ec_group_set_gfp521(ECGroup *group, ECCurveName name)
|
| +{
|
| + if (name == ECCurve_NIST_P521) {
|
| + group->meth->field_mod = &ec_GFp_nistp521_mod;
|
| + group->meth->field_mul = &ec_GFp_nistp521_mul;
|
| + group->meth->field_sqr = &ec_GFp_nistp521_sqr;
|
| + group->meth->field_div = &ec_GFp_nistp521_div;
|
| + }
|
| + return MP_OKAY;
|
| +}
|
|
|
| Property changes on: nss/lib/freebl/ecl/ecp_521.c
|
| ___________________________________________________________________
|
| Added: svn:eol-style
|
| + LF
|
|
|
|
|