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 |