1 /* Copyright (c) 2018, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15 #include <openssl/ec.h>
16 #include <openssl/err.h>
17 #include <openssl/mem.h>
18
19 #include "internal.h"
20 #include "../bn/internal.h"
21 #include "../../internal.h"
22
23
ec_bignum_to_scalar(const EC_GROUP * group,EC_SCALAR * out,const BIGNUM * in)24 int ec_bignum_to_scalar(const EC_GROUP *group, EC_SCALAR *out,
25 const BIGNUM *in) {
26 if (!bn_copy_words(out->words, group->order.width, in) ||
27 !bn_less_than_words(out->words, group->order.d, group->order.width)) {
28 OPENSSL_PUT_ERROR(EC, EC_R_INVALID_SCALAR);
29 return 0;
30 }
31 return 1;
32 }
33
ec_scalar_equal_vartime(const EC_GROUP * group,const EC_SCALAR * a,const EC_SCALAR * b)34 int ec_scalar_equal_vartime(const EC_GROUP *group, const EC_SCALAR *a,
35 const EC_SCALAR *b) {
36 return OPENSSL_memcmp(a->words, b->words,
37 group->order.width * sizeof(BN_ULONG)) == 0;
38 }
39
ec_scalar_is_zero(const EC_GROUP * group,const EC_SCALAR * a)40 int ec_scalar_is_zero(const EC_GROUP *group, const EC_SCALAR *a) {
41 BN_ULONG mask = 0;
42 for (int i = 0; i < group->order.width; i++) {
43 mask |= a->words[i];
44 }
45 return mask == 0;
46 }
47
ec_random_nonzero_scalar(const EC_GROUP * group,EC_SCALAR * out,const uint8_t additional_data[32])48 int ec_random_nonzero_scalar(const EC_GROUP *group, EC_SCALAR *out,
49 const uint8_t additional_data[32]) {
50 return bn_rand_range_words(out->words, 1, group->order.d, group->order.width,
51 additional_data);
52 }
53
ec_scalar_add(const EC_GROUP * group,EC_SCALAR * r,const EC_SCALAR * a,const EC_SCALAR * b)54 void ec_scalar_add(const EC_GROUP *group, EC_SCALAR *r, const EC_SCALAR *a,
55 const EC_SCALAR *b) {
56 const BIGNUM *order = &group->order;
57 BN_ULONG tmp[EC_MAX_WORDS];
58 bn_mod_add_words(r->words, a->words, b->words, order->d, tmp, order->width);
59 OPENSSL_cleanse(tmp, sizeof(tmp));
60 }
61
ec_scalar_to_montgomery(const EC_GROUP * group,EC_SCALAR * r,const EC_SCALAR * a)62 void ec_scalar_to_montgomery(const EC_GROUP *group, EC_SCALAR *r,
63 const EC_SCALAR *a) {
64 const BIGNUM *order = &group->order;
65 bn_to_montgomery_small(r->words, a->words, order->width, group->order_mont);
66 }
67
ec_scalar_from_montgomery(const EC_GROUP * group,EC_SCALAR * r,const EC_SCALAR * a)68 void ec_scalar_from_montgomery(const EC_GROUP *group, EC_SCALAR *r,
69 const EC_SCALAR *a) {
70 const BIGNUM *order = &group->order;
71 bn_from_montgomery_small(r->words, a->words, order->width, group->order_mont);
72 }
73
ec_scalar_mul_montgomery(const EC_GROUP * group,EC_SCALAR * r,const EC_SCALAR * a,const EC_SCALAR * b)74 void ec_scalar_mul_montgomery(const EC_GROUP *group, EC_SCALAR *r,
75 const EC_SCALAR *a, const EC_SCALAR *b) {
76 const BIGNUM *order = &group->order;
77 bn_mod_mul_montgomery_small(r->words, a->words, b->words, order->width,
78 group->order_mont);
79 }
80
ec_simple_scalar_inv_montgomery(const EC_GROUP * group,EC_SCALAR * r,const EC_SCALAR * a)81 void ec_simple_scalar_inv_montgomery(const EC_GROUP *group, EC_SCALAR *r,
82 const EC_SCALAR *a) {
83 const BIGNUM *order = &group->order;
84 bn_mod_inverse_prime_mont_small(r->words, a->words, order->width,
85 group->order_mont);
86 }
87
ec_scalar_inv_montgomery(const EC_GROUP * group,EC_SCALAR * r,const EC_SCALAR * a)88 void ec_scalar_inv_montgomery(const EC_GROUP *group, EC_SCALAR *r,
89 const EC_SCALAR *a) {
90 group->meth->scalar_inv_montgomery(group, r, a);
91 }
92
ec_scalar_inv_montgomery_vartime(const EC_GROUP * group,EC_SCALAR * r,const EC_SCALAR * a)93 int ec_scalar_inv_montgomery_vartime(const EC_GROUP *group, EC_SCALAR *r,
94 const EC_SCALAR *a) {
95 return group->meth->scalar_inv_montgomery_vartime(group, r, a);
96 }
97