import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

security/nss/lib/freebl/ecl/ecp_mont.c

@@ -0,0 +1,154 @@
+/* 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/. */
+
+/* Uses Montgomery reduction for field arithmetic.  See mpi/mpmontg.c for
+ * code implementation. */
+
+#include "mpi.h"
+#include "mplogic.h"
+#include "mpi-priv.h"
+#include "ecl-priv.h"
+#include "ecp.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+/* Construct a generic GFMethod for arithmetic over prime fields with
+ * irreducible irr. */
+GFMethod *
+GFMethod_consGFp_mont(const mp_int *irr)
+{
+    mp_err res = MP_OKAY;
+    GFMethod *meth = NULL;
+    mp_mont_modulus *mmm;
+
+    meth = GFMethod_consGFp(irr);
+    if (meth == NULL)
+        return NULL;
+
+    mmm = (mp_mont_modulus *)malloc(sizeof(mp_mont_modulus));
+    if (mmm == NULL) {
+        res = MP_MEM;
+        goto CLEANUP;
+    }
+
+    meth->field_mul = &ec_GFp_mul_mont;
+    meth->field_sqr = &ec_GFp_sqr_mont;
+    meth->field_div = &ec_GFp_div_mont;
+    meth->field_enc = &ec_GFp_enc_mont;
+    meth->field_dec = &ec_GFp_dec_mont;
+    meth->extra1 = mmm;
+    meth->extra2 = NULL;
+    meth->extra_free = &ec_GFp_extra_free_mont;
+
+    mmm->N = meth->irr;
+    mmm->n0prime = 0 - s_mp_invmod_radix(MP_DIGIT(&meth->irr, 0));
+
+CLEANUP:
+    if (res != MP_OKAY) {
+        GFMethod_free(meth);
+        return NULL;
+    }
+    return meth;
+}
+
+/* Wrapper functions for generic prime field arithmetic. */
+
+/* Field multiplication using Montgomery reduction. */
+mp_err
+ec_GFp_mul_mont(const mp_int *a, const mp_int *b, mp_int *r,
+                const GFMethod *meth)
+{
+    mp_err res = MP_OKAY;
+
+#ifdef MP_MONT_USE_MP_MUL
+    /* if MP_MONT_USE_MP_MUL is defined, then the function s_mp_mul_mont
+     * is not implemented and we have to use mp_mul and s_mp_redc directly
+     */
+    MP_CHECKOK(mp_mul(a, b, r));
+    MP_CHECKOK(s_mp_redc(r, (mp_mont_modulus *)meth->extra1));
+#else
+    mp_int s;
+
+    MP_DIGITS(&s) = 0;
+    /* s_mp_mul_mont doesn't allow source and destination to be the same */
+    if ((a == r) || (b == r)) {
+        MP_CHECKOK(mp_init(&s));
+        MP_CHECKOK(s_mp_mul_mont(a, b, &s, (mp_mont_modulus *)meth->extra1));
+        MP_CHECKOK(mp_copy(&s, r));
+        mp_clear(&s);
+    } else {
+        return s_mp_mul_mont(a, b, r, (mp_mont_modulus *)meth->extra1);
+    }
+#endif
+CLEANUP:
+    return res;
+}
+
+/* Field squaring using Montgomery reduction. */
+mp_err
+ec_GFp_sqr_mont(const mp_int *a, mp_int *r, const GFMethod *meth)
+{
+    return ec_GFp_mul_mont(a, a, r, meth);
+}
+
+/* Field division using Montgomery reduction. */
+mp_err
+ec_GFp_div_mont(const mp_int *a, const mp_int *b, mp_int *r,
+                const GFMethod *meth)
+{
+    mp_err res = MP_OKAY;
+
+    /* if A=aZ represents a encoded in montgomery coordinates with Z and #
+     * and \ respectively represent multiplication and division in
+     * montgomery coordinates, then A\B = (a/b)Z = (A/B)Z and Binv =
+     * (1/b)Z = (1/B)(Z^2) where B # Binv = Z */
+    MP_CHECKOK(ec_GFp_div(a, b, r, meth));
+    MP_CHECKOK(ec_GFp_enc_mont(r, r, meth));
+    if (a == NULL) {
+        MP_CHECKOK(ec_GFp_enc_mont(r, r, meth));
+    }
+CLEANUP:
+    return res;
+}
+
+/* Encode a field element in Montgomery form. See s_mp_to_mont in
+ * mpi/mpmontg.c */
+mp_err
+ec_GFp_enc_mont(const mp_int *a, mp_int *r, const GFMethod *meth)
+{
+    mp_mont_modulus *mmm;
+    mp_err res = MP_OKAY;
+
+    mmm = (mp_mont_modulus *)meth->extra1;
+    MP_CHECKOK(mp_copy(a, r));
+    MP_CHECKOK(s_mp_lshd(r, MP_USED(&mmm->N)));
+    MP_CHECKOK(mp_mod(r, &mmm->N, r));
+CLEANUP:
+    return res;
+}
+
+/* Decode a field element from Montgomery form. */
+mp_err
+ec_GFp_dec_mont(const mp_int *a, mp_int *r, const GFMethod *meth)
+{
+    mp_err res = MP_OKAY;
+
+    if (a != r) {
+        MP_CHECKOK(mp_copy(a, r));
+    }
+    MP_CHECKOK(s_mp_redc(r, (mp_mont_modulus *)meth->extra1));
+CLEANUP:
+    return res;
+}
+
+/* Free the memory allocated to the extra fields of Montgomery GFMethod
+ * object. */
+void
+ec_GFp_extra_free_mont(GFMethod *meth)
+{
+    if (meth->extra1 != NULL) {
+        free(meth->extra1);
+        meth->extra1 = NULL;
+    }
+}