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/*
* Copyright 2001-2019 The OpenSSL Project Authors. All Rights Reserved.
* Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <openssl/err.h>
#include "ec_local.h"
const EC_METHOD *EC_GFp_mont_method(void)
{
static const EC_METHOD ret = {
EC_FLAGS_DEFAULT_OCT,
NID_X9_62_prime_field,
ec_GFp_mont_group_init,
ec_GFp_mont_group_finish,
ec_GFp_mont_group_clear_finish,
ec_GFp_mont_group_copy,
ec_GFp_mont_group_set_curve,
ec_GFp_simple_group_get_curve,
ec_GFp_simple_group_get_degree,
ec_group_simple_order_bits,
ec_GFp_simple_group_check_discriminant,
ec_GFp_simple_point_init,
ec_GFp_simple_point_finish,
ec_GFp_simple_point_clear_finish,
ec_GFp_simple_point_copy,
ec_GFp_simple_point_set_to_infinity,
ec_GFp_simple_set_Jprojective_coordinates_GFp,
ec_GFp_simple_get_Jprojective_coordinates_GFp,
ec_GFp_simple_point_set_affine_coordinates,
ec_GFp_simple_point_get_affine_coordinates,
0, 0, 0,
ec_GFp_simple_add,
ec_GFp_simple_dbl,
ec_GFp_simple_invert,
ec_GFp_simple_is_at_infinity,
ec_GFp_simple_is_on_curve,
ec_GFp_simple_cmp,
ec_GFp_simple_make_affine,
ec_GFp_simple_points_make_affine,
0 /* mul */ ,
0 /* precompute_mult */ ,
0 /* have_precompute_mult */ ,
ec_GFp_mont_field_mul,
ec_GFp_mont_field_sqr,
0 /* field_div */ ,
ec_GFp_mont_field_inv,
ec_GFp_mont_field_encode,
ec_GFp_mont_field_decode,
ec_GFp_mont_field_set_to_one,
ec_key_simple_priv2oct,
ec_key_simple_oct2priv,
0, /* set private */
ec_key_simple_generate_key,
ec_key_simple_check_key,
ec_key_simple_generate_public_key,
0, /* keycopy */
0, /* keyfinish */
ecdh_simple_compute_key,
0, /* field_inverse_mod_ord */
ec_GFp_simple_blind_coordinates,
ec_GFp_simple_ladder_pre,
ec_GFp_simple_ladder_step,
ec_GFp_simple_ladder_post
};
return &ret;
}
int ec_GFp_mont_group_init(EC_GROUP *group)
{
int ok;
ok = ec_GFp_simple_group_init(group);
group->field_data1 = NULL;
group->field_data2 = NULL;
return ok;
}
void ec_GFp_mont_group_finish(EC_GROUP *group)
{
BN_MONT_CTX_free(group->field_data1);
group->field_data1 = NULL;
BN_free(group->field_data2);
group->field_data2 = NULL;
ec_GFp_simple_group_finish(group);
}
void ec_GFp_mont_group_clear_finish(EC_GROUP *group)
{
BN_MONT_CTX_free(group->field_data1);
group->field_data1 = NULL;
BN_clear_free(group->field_data2);
group->field_data2 = NULL;
ec_GFp_simple_group_clear_finish(group);
}
int ec_GFp_mont_group_copy(EC_GROUP *dest, const EC_GROUP *src)
{
BN_MONT_CTX_free(dest->field_data1);
dest->field_data1 = NULL;
BN_clear_free(dest->field_data2);
dest->field_data2 = NULL;
if (!ec_GFp_simple_group_copy(dest, src))
return 0;
if (src->field_data1 != NULL) {
dest->field_data1 = BN_MONT_CTX_new();
if (dest->field_data1 == NULL)
return 0;
if (!BN_MONT_CTX_copy(dest->field_data1, src->field_data1))
goto err;
}
if (src->field_data2 != NULL) {
dest->field_data2 = BN_dup(src->field_data2);
if (dest->field_data2 == NULL)
goto err;
}
return 1;
err:
BN_MONT_CTX_free(dest->field_data1);
dest->field_data1 = NULL;
return 0;
}
int ec_GFp_mont_group_set_curve(EC_GROUP *group, const BIGNUM *p,
const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
{
BN_CTX *new_ctx = NULL;
BN_MONT_CTX *mont = NULL;
BIGNUM *one = NULL;
int ret = 0;
BN_MONT_CTX_free(group->field_data1);
group->field_data1 = NULL;
BN_free(group->field_data2);
group->field_data2 = NULL;
if (ctx == NULL) {
ctx = new_ctx = BN_CTX_new();
if (ctx == NULL)
return 0;
}
mont = BN_MONT_CTX_new();
if (mont == NULL)
goto err;
if (!BN_MONT_CTX_set(mont, p, ctx)) {
ECerr(EC_F_EC_GFP_MONT_GROUP_SET_CURVE, ERR_R_BN_LIB);
goto err;
}
one = BN_new();
if (one == NULL)
goto err;
if (!BN_to_montgomery(one, BN_value_one(), mont, ctx))
goto err;
group->field_data1 = mont;
mont = NULL;
group->field_data2 = one;
one = NULL;
ret = ec_GFp_simple_group_set_curve(group, p, a, b, ctx);
if (!ret) {
BN_MONT_CTX_free(group->field_data1);
group->field_data1 = NULL;
BN_free(group->field_data2);
group->field_data2 = NULL;
}
err:
BN_free(one);
BN_CTX_free(new_ctx);
BN_MONT_CTX_free(mont);
return ret;
}
int ec_GFp_mont_field_mul(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
const BIGNUM *b, BN_CTX *ctx)
{
if (group->field_data1 == NULL) {
ECerr(EC_F_EC_GFP_MONT_FIELD_MUL, EC_R_NOT_INITIALIZED);
return 0;
}
return BN_mod_mul_montgomery(r, a, b, group->field_data1, ctx);
}
int ec_GFp_mont_field_sqr(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
BN_CTX *ctx)
{
if (group->field_data1 == NULL) {
ECerr(EC_F_EC_GFP_MONT_FIELD_SQR, EC_R_NOT_INITIALIZED);
return 0;
}
return BN_mod_mul_montgomery(r, a, a, group->field_data1, ctx);
}
/*-
* Computes the multiplicative inverse of a in GF(p), storing the result in r.
* If a is zero (or equivalent), you'll get a EC_R_CANNOT_INVERT error.
* We have a Mont structure, so SCA hardening is FLT inversion.
*/
int ec_GFp_mont_field_inv(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
BN_CTX *ctx)
{
BIGNUM *e = NULL;
BN_CTX *new_ctx = NULL;
int ret = 0;
if (group->field_data1 == NULL)
return 0;
if (ctx == NULL && (ctx = new_ctx = BN_CTX_secure_new()) == NULL)
return 0;
BN_CTX_start(ctx);
if ((e = BN_CTX_get(ctx)) == NULL)
goto err;
/* Inverse in constant time with Fermats Little Theorem */
if (!BN_set_word(e, 2))
goto err;
if (!BN_sub(e, group->field, e))
goto err;
/*-
* Exponent e is public.
* No need for scatter-gather or BN_FLG_CONSTTIME.
*/
if (!BN_mod_exp_mont(r, a, e, group->field, ctx, group->field_data1))
goto err;
/* throw an error on zero */
if (BN_is_zero(r)) {
ECerr(EC_F_EC_GFP_MONT_FIELD_INV, EC_R_CANNOT_INVERT);
goto err;
}
ret = 1;
err:
BN_CTX_end(ctx);
BN_CTX_free(new_ctx);
return ret;
}
int ec_GFp_mont_field_encode(const EC_GROUP *group, BIGNUM *r,
const BIGNUM *a, BN_CTX *ctx)
{
if (group->field_data1 == NULL) {
ECerr(EC_F_EC_GFP_MONT_FIELD_ENCODE, EC_R_NOT_INITIALIZED);
return 0;
}
return BN_to_montgomery(r, a, (BN_MONT_CTX *)group->field_data1, ctx);
}
int ec_GFp_mont_field_decode(const EC_GROUP *group, BIGNUM *r,
const BIGNUM *a, BN_CTX *ctx)
{
if (group->field_data1 == NULL) {
ECerr(EC_F_EC_GFP_MONT_FIELD_DECODE, EC_R_NOT_INITIALIZED);
return 0;
}
return BN_from_montgomery(r, a, group->field_data1, ctx);
}
int ec_GFp_mont_field_set_to_one(const EC_GROUP *group, BIGNUM *r,
BN_CTX *ctx)
{
if (group->field_data2 == NULL) {
ECerr(EC_F_EC_GFP_MONT_FIELD_SET_TO_ONE, EC_R_NOT_INITIALIZED);
return 0;
}
if (!BN_copy(r, group->field_data2))
return 0;
return 1;
}
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