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
24int 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
34int 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
40int 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
48int 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
54void 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
62void 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
68void 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
74void 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
81void 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
88void 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
93int 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