Delete bundled copy of NSS and replace with README.

nss/lib/freebl/ecl/ecp_521.c

-/* 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);
-        unsigned 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;
-}