--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nss/lib/freebl/ecl/ecp_521.c	Mon Jul 28 10:47:06 2014 +0200
@@ -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;
+}