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Diffstat (limited to '')
-rw-r--r-- | security/nss/lib/freebl/ecl/ecp_mont.c | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/security/nss/lib/freebl/ecl/ecp_mont.c b/security/nss/lib/freebl/ecl/ecp_mont.c new file mode 100644 index 0000000000..779685b4dd --- /dev/null +++ b/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; + } +} |