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Abstract away EC_SCALAR operations.

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Just a little bit cleaner.

Change-Id: I0ed192a531b5aa853ba082caa6088e838f12c863
Reviewed-on: https://boringssl-review.googlesource.com/27587
Reviewed-by: Adam Langley <alangley@gmail.com>
This commit is contained in:
David Benjamin 2018-04-04 23:36:15 -04:00 committed by Adam Langley
parent 9291be5b27
commit 941f535438
5 changed files with 112 additions and 55 deletions
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1
crypto/fipsmodule/bcm.c
View File

@ -63,6 +63,7 @@
#include "ec/p224-64.c"
#include "../../third_party/fiat/p256.c"
#include "ec/p256-x86_64.c"
#include "ec/scalar.c"
#include "ec/simple.c"
#include "ec/util.c"
#include "ec/wnaf.c"

27
crypto/fipsmodule/ec/ec.c
View File

@ -955,30 +955,3 @@ size_t EC_get_builtin_curves(EC_builtin_curve *out_curves,
return OPENSSL_NUM_BUILT_IN_CURVES;
}
int ec_bignum_to_scalar(const EC_GROUP *group, EC_SCALAR *out,
const BIGNUM *in) {
if (!ec_bignum_to_scalar_unchecked(group, out, in)) {
return 0;
}
if (!bn_less_than_words(out->words, group->order.d, group->order.width)) {
OPENSSL_PUT_ERROR(EC, EC_R_INVALID_SCALAR);
return 0;
}
return 1;
}
int ec_bignum_to_scalar_unchecked(const EC_GROUP *group, EC_SCALAR *out,
const BIGNUM *in) {
if (!bn_copy_words(out->words, group->order.width, in)) {
OPENSSL_PUT_ERROR(EC, EC_R_INVALID_SCALAR);
return 0;
}
return 1;
}
int ec_random_nonzero_scalar(const EC_GROUP *group, EC_SCALAR *out,
const uint8_t additional_data[32]) {
return bn_rand_range_words(out->words, 1, group->order.d, group->order.width,
additional_data);
}

22
crypto/fipsmodule/ec/internal.h
View File

@ -193,6 +193,28 @@ int ec_bignum_to_scalar_unchecked(const EC_GROUP *group, EC_SCALAR *out,
int ec_random_nonzero_scalar(const EC_GROUP *group, EC_SCALAR *out,
const uint8_t additional_data[32]);
// ec_scalar_add sets |r| to |a| + |b|.
void ec_scalar_add(const EC_GROUP *group, EC_SCALAR *r, const EC_SCALAR *a,
const EC_SCALAR *b);
// ec_scalar_to_montgomery sets |r| to |a| in Montgomery form.
void ec_scalar_to_montgomery(const EC_GROUP *group, EC_SCALAR *r,
const EC_SCALAR *a);
// ec_scalar_to_montgomery sets |r| to |a| converted from Montgomery form.
void ec_scalar_from_montgomery(const EC_GROUP *group, EC_SCALAR *r,
const EC_SCALAR *a);
// ec_scalar_mul_montgomery sets |r| to |a| * |b| where inputs and outputs are
// in Montgomery form.
void ec_scalar_mul_montgomery(const EC_GROUP *group, EC_SCALAR *r,
const EC_SCALAR *a, const EC_SCALAR *b);
// ec_scalar_mul_montgomery sets |r| to |a|^-1 where inputs and outputs are in
// Montgomery form.
void ec_scalar_inv_montgomery(const EC_GROUP *group, EC_SCALAR *r,
const EC_SCALAR *a);
// ec_point_add_mixed behaves like |EC_POINT_add|, but |&b->Z| must be zero or
// one.
int ec_point_add_mixed(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a,

80
crypto/fipsmodule/ec/scalar.c Normal file
View File

@ -0,0 +1,80 @@
/* Copyright (c) 2018, Google Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#include <openssl/ec.h>
#include "internal.h"
#include "../bn/internal.h"
int ec_bignum_to_scalar(const EC_GROUP *group, EC_SCALAR *out,
const BIGNUM *in) {
if (!ec_bignum_to_scalar_unchecked(group, out, in)) {
return 0;
}
if (!bn_less_than_words(out->words, group->order.d, group->order.width)) {
OPENSSL_PUT_ERROR(EC, EC_R_INVALID_SCALAR);
return 0;
}
return 1;
}
int ec_bignum_to_scalar_unchecked(const EC_GROUP *group, EC_SCALAR *out,
const BIGNUM *in) {
if (!bn_copy_words(out->words, group->order.width, in)) {
OPENSSL_PUT_ERROR(EC, EC_R_INVALID_SCALAR);
return 0;
}
return 1;
}
int ec_random_nonzero_scalar(const EC_GROUP *group, EC_SCALAR *out,
const uint8_t additional_data[32]) {
return bn_rand_range_words(out->words, 1, group->order.d, group->order.width,
additional_data);
}
void ec_scalar_add(const EC_GROUP *group, EC_SCALAR *r, const EC_SCALAR *a,
const EC_SCALAR *b) {
const BIGNUM *order = &group->order;
BN_ULONG tmp[EC_MAX_SCALAR_WORDS];
bn_mod_add_words(r->words, a->words, b->words, order->d, tmp, order->width);
OPENSSL_cleanse(tmp, sizeof(tmp));
}
void ec_scalar_to_montgomery(const EC_GROUP *group, EC_SCALAR *r,
const EC_SCALAR *a) {
const BIGNUM *order = &group->order;
bn_to_montgomery_small(r->words, a->words, order->width, group->order_mont);
}
void ec_scalar_from_montgomery(const EC_GROUP *group, EC_SCALAR *r,
const EC_SCALAR *a) {
const BIGNUM *order = &group->order;
bn_from_montgomery_small(r->words, a->words, order->width, group->order_mont);
}
void ec_scalar_mul_montgomery(const EC_GROUP *group, EC_SCALAR *r,
const EC_SCALAR *a, const EC_SCALAR *b) {
const BIGNUM *order = &group->order;
bn_mod_mul_montgomery_small(r->words, a->words, b->words, order->width,
group->order_mont);
}
void ec_scalar_inv_montgomery(const EC_GROUP *group, EC_SCALAR *r,
const EC_SCALAR *a) {
const BIGNUM *order = &group->order;
bn_mod_inverse_prime_mont_small(r->words, a->words, order->width,
group->order_mont);
}

37
crypto/fipsmodule/ecdsa/ecdsa.c
View File

@ -66,21 +66,6 @@
#include "../../internal.h"
static void scalar_add(const EC_GROUP *group, EC_SCALAR *r, const EC_SCALAR *a,
const EC_SCALAR *b) {
const BIGNUM *order = &group->order;
BN_ULONG tmp[EC_MAX_SCALAR_WORDS];
bn_mod_add_words(r->words, a->words, b->words, order->d, tmp, order->width);
OPENSSL_cleanse(tmp, sizeof(tmp));
}
static void scalar_mul_montgomery(const EC_GROUP *group, EC_SCALAR *r,
const EC_SCALAR *a, const EC_SCALAR *b) {
const BIGNUM *order = &group->order;
bn_mod_mul_montgomery_small(r->words, a->words, b->words, order->width,
group->order_mont);
}
// digest_to_scalar interprets |digest_len| bytes from |digest| as a scalar for
// ECDSA. Note this value is not fully reduced modulo the order, only the
// correct number of bits.
@ -233,16 +218,15 @@ int ECDSA_do_verify(const uint8_t *digest, size_t digest_len,
!ec_bignum_to_scalar_unchecked(group, &s_inv_mont, X)) {
goto err;
}
bn_to_montgomery_small(s_inv_mont.words, s_inv_mont.words, order->width,
group->order_mont);
ec_scalar_to_montgomery(group, &s_inv_mont, &s_inv_mont);
// u1 = m * s^-1 mod order
// u2 = r * s^-1 mod order
//
// |s_inv_mont| is in Montgomery form while |m| and |r| are not, so |u1| and
// |u2| will be taken out of Montgomery form, as desired.
digest_to_scalar(group, &m, digest, digest_len);
scalar_mul_montgomery(group, &u1, &m, &s_inv_mont);
scalar_mul_montgomery(group, &u2, &r, &s_inv_mont);
ec_scalar_mul_montgomery(group, &u1, &m, &s_inv_mont);
ec_scalar_mul_montgomery(group, &u2, &r, &s_inv_mont);
point = EC_POINT_new(group);
if (point == NULL) {
@ -327,10 +311,8 @@ static int ecdsa_sign_setup(const EC_KEY *eckey, BN_CTX *ctx,
// Compute k^-1. We leave it in the Montgomery domain as an optimization for
// later operations.
bn_to_montgomery_small(out_kinv_mont->words, k.words, order->width,
group->order_mont);
bn_mod_inverse_prime_mont_small(out_kinv_mont->words, out_kinv_mont->words,
order->width, group->order_mont);
ec_scalar_to_montgomery(group, out_kinv_mont, &k);
ec_scalar_inv_montgomery(group, out_kinv_mont, out_kinv_mont);
// Compute r, the x-coordinate of generator * k.
if (!ec_point_mul_scalar(group, tmp_point, &k, NULL, NULL, ctx) ||
@ -393,16 +375,15 @@ ECDSA_SIG *ECDSA_do_sign(const uint8_t *digest, size_t digest_len,
if (!ec_bignum_to_scalar(group, &r_mont, ret->r)) {
goto err;
}
bn_to_montgomery_small(r_mont.words, r_mont.words, order->width,
group->order_mont);
scalar_mul_montgomery(group, &s, priv_key, &r_mont);
ec_scalar_to_montgomery(group, &r_mont, &r_mont);
ec_scalar_mul_montgomery(group, &s, priv_key, &r_mont);
// Compute tmp = m + priv_key * r.
scalar_add(group, &tmp, &m, &s);
ec_scalar_add(group, &tmp, &m, &s);
// Finally, multiply s by k^-1. That was retained in Montgomery form, so the
// same technique as the previous multiplication works.
scalar_mul_montgomery(group, &s, &tmp, &kinv_mont);
ec_scalar_mul_montgomery(group, &s, &tmp, &kinv_mont);
if (!bn_set_words(ret->s, s.words, order->width)) {
goto err;
}