1 /*
2 * Copyright 2001-2021 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
4 *
5 * Licensed under the Apache License 2.0 (the "License"). You may not use
6 * this file except in compliance with the License. You can obtain a copy
7 * in the file LICENSE in the source distribution or at
8 * https://www.openssl.org/source/license.html
9 */
10
11 /*
12 * ECDSA low-level APIs are deprecated for public use, but still ok for
13 * internal use.
14 */
15 #include "internal/deprecated.h"
16
17 #include <openssl/err.h>
18
19 #include "ec_local.h"
20
EC_GFp_mont_method(void)21 const EC_METHOD *EC_GFp_mont_method(void)
22 {
23 static const EC_METHOD ret = {
24 EC_FLAGS_DEFAULT_OCT,
25 NID_X9_62_prime_field,
26 ossl_ec_GFp_mont_group_init,
27 ossl_ec_GFp_mont_group_finish,
28 ossl_ec_GFp_mont_group_clear_finish,
29 ossl_ec_GFp_mont_group_copy,
30 ossl_ec_GFp_mont_group_set_curve,
31 ossl_ec_GFp_simple_group_get_curve,
32 ossl_ec_GFp_simple_group_get_degree,
33 ossl_ec_group_simple_order_bits,
34 ossl_ec_GFp_simple_group_check_discriminant,
35 ossl_ec_GFp_simple_point_init,
36 ossl_ec_GFp_simple_point_finish,
37 ossl_ec_GFp_simple_point_clear_finish,
38 ossl_ec_GFp_simple_point_copy,
39 ossl_ec_GFp_simple_point_set_to_infinity,
40 ossl_ec_GFp_simple_point_set_affine_coordinates,
41 ossl_ec_GFp_simple_point_get_affine_coordinates,
42 0, 0, 0,
43 ossl_ec_GFp_simple_add,
44 ossl_ec_GFp_simple_dbl,
45 ossl_ec_GFp_simple_invert,
46 ossl_ec_GFp_simple_is_at_infinity,
47 ossl_ec_GFp_simple_is_on_curve,
48 ossl_ec_GFp_simple_cmp,
49 ossl_ec_GFp_simple_make_affine,
50 ossl_ec_GFp_simple_points_make_affine,
51 0 /* mul */ ,
52 0 /* precompute_mult */ ,
53 0 /* have_precompute_mult */ ,
54 ossl_ec_GFp_mont_field_mul,
55 ossl_ec_GFp_mont_field_sqr,
56 0 /* field_div */ ,
57 ossl_ec_GFp_mont_field_inv,
58 ossl_ec_GFp_mont_field_encode,
59 ossl_ec_GFp_mont_field_decode,
60 ossl_ec_GFp_mont_field_set_to_one,
61 ossl_ec_key_simple_priv2oct,
62 ossl_ec_key_simple_oct2priv,
63 0, /* set private */
64 ossl_ec_key_simple_generate_key,
65 ossl_ec_key_simple_check_key,
66 ossl_ec_key_simple_generate_public_key,
67 0, /* keycopy */
68 0, /* keyfinish */
69 ossl_ecdh_simple_compute_key,
70 ossl_ecdsa_simple_sign_setup,
71 ossl_ecdsa_simple_sign_sig,
72 ossl_ecdsa_simple_verify_sig,
73 0, /* field_inverse_mod_ord */
74 ossl_ec_GFp_simple_blind_coordinates,
75 ossl_ec_GFp_simple_ladder_pre,
76 ossl_ec_GFp_simple_ladder_step,
77 ossl_ec_GFp_simple_ladder_post
78 };
79
80 return &ret;
81 }
82
ossl_ec_GFp_mont_group_init(EC_GROUP * group)83 int ossl_ec_GFp_mont_group_init(EC_GROUP *group)
84 {
85 int ok;
86
87 ok = ossl_ec_GFp_simple_group_init(group);
88 group->field_data1 = NULL;
89 group->field_data2 = NULL;
90 return ok;
91 }
92
ossl_ec_GFp_mont_group_finish(EC_GROUP * group)93 void ossl_ec_GFp_mont_group_finish(EC_GROUP *group)
94 {
95 BN_MONT_CTX_free(group->field_data1);
96 group->field_data1 = NULL;
97 BN_free(group->field_data2);
98 group->field_data2 = NULL;
99 ossl_ec_GFp_simple_group_finish(group);
100 }
101
ossl_ec_GFp_mont_group_clear_finish(EC_GROUP * group)102 void ossl_ec_GFp_mont_group_clear_finish(EC_GROUP *group)
103 {
104 BN_MONT_CTX_free(group->field_data1);
105 group->field_data1 = NULL;
106 BN_clear_free(group->field_data2);
107 group->field_data2 = NULL;
108 ossl_ec_GFp_simple_group_clear_finish(group);
109 }
110
ossl_ec_GFp_mont_group_copy(EC_GROUP * dest,const EC_GROUP * src)111 int ossl_ec_GFp_mont_group_copy(EC_GROUP *dest, const EC_GROUP *src)
112 {
113 BN_MONT_CTX_free(dest->field_data1);
114 dest->field_data1 = NULL;
115 BN_clear_free(dest->field_data2);
116 dest->field_data2 = NULL;
117
118 if (!ossl_ec_GFp_simple_group_copy(dest, src))
119 return 0;
120
121 if (src->field_data1 != NULL) {
122 dest->field_data1 = BN_MONT_CTX_new();
123 if (dest->field_data1 == NULL)
124 return 0;
125 if (!BN_MONT_CTX_copy(dest->field_data1, src->field_data1))
126 goto err;
127 }
128 if (src->field_data2 != NULL) {
129 dest->field_data2 = BN_dup(src->field_data2);
130 if (dest->field_data2 == NULL)
131 goto err;
132 }
133
134 return 1;
135
136 err:
137 BN_MONT_CTX_free(dest->field_data1);
138 dest->field_data1 = NULL;
139 return 0;
140 }
141
ossl_ec_GFp_mont_group_set_curve(EC_GROUP * group,const BIGNUM * p,const BIGNUM * a,const BIGNUM * b,BN_CTX * ctx)142 int ossl_ec_GFp_mont_group_set_curve(EC_GROUP *group, const BIGNUM *p,
143 const BIGNUM *a, const BIGNUM *b,
144 BN_CTX *ctx)
145 {
146 BN_CTX *new_ctx = NULL;
147 BN_MONT_CTX *mont = NULL;
148 BIGNUM *one = NULL;
149 int ret = 0;
150
151 BN_MONT_CTX_free(group->field_data1);
152 group->field_data1 = NULL;
153 BN_free(group->field_data2);
154 group->field_data2 = NULL;
155
156 if (ctx == NULL) {
157 ctx = new_ctx = BN_CTX_new_ex(group->libctx);
158 if (ctx == NULL)
159 return 0;
160 }
161
162 mont = BN_MONT_CTX_new();
163 if (mont == NULL)
164 goto err;
165 if (!BN_MONT_CTX_set(mont, p, ctx)) {
166 ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
167 goto err;
168 }
169 one = BN_new();
170 if (one == NULL)
171 goto err;
172 if (!BN_to_montgomery(one, BN_value_one(), mont, ctx))
173 goto err;
174
175 group->field_data1 = mont;
176 mont = NULL;
177 group->field_data2 = one;
178 one = NULL;
179
180 ret = ossl_ec_GFp_simple_group_set_curve(group, p, a, b, ctx);
181
182 if (!ret) {
183 BN_MONT_CTX_free(group->field_data1);
184 group->field_data1 = NULL;
185 BN_free(group->field_data2);
186 group->field_data2 = NULL;
187 }
188
189 err:
190 BN_free(one);
191 BN_CTX_free(new_ctx);
192 BN_MONT_CTX_free(mont);
193 return ret;
194 }
195
ossl_ec_GFp_mont_field_mul(const EC_GROUP * group,BIGNUM * r,const BIGNUM * a,const BIGNUM * b,BN_CTX * ctx)196 int ossl_ec_GFp_mont_field_mul(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
197 const BIGNUM *b, BN_CTX *ctx)
198 {
199 if (group->field_data1 == NULL) {
200 ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
201 return 0;
202 }
203
204 return BN_mod_mul_montgomery(r, a, b, group->field_data1, ctx);
205 }
206
ossl_ec_GFp_mont_field_sqr(const EC_GROUP * group,BIGNUM * r,const BIGNUM * a,BN_CTX * ctx)207 int ossl_ec_GFp_mont_field_sqr(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
208 BN_CTX *ctx)
209 {
210 if (group->field_data1 == NULL) {
211 ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
212 return 0;
213 }
214
215 return BN_mod_mul_montgomery(r, a, a, group->field_data1, ctx);
216 }
217
218 /*-
219 * Computes the multiplicative inverse of a in GF(p), storing the result in r.
220 * If a is zero (or equivalent), you'll get an EC_R_CANNOT_INVERT error.
221 * We have a Mont structure, so SCA hardening is FLT inversion.
222 */
ossl_ec_GFp_mont_field_inv(const EC_GROUP * group,BIGNUM * r,const BIGNUM * a,BN_CTX * ctx)223 int ossl_ec_GFp_mont_field_inv(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
224 BN_CTX *ctx)
225 {
226 BIGNUM *e = NULL;
227 BN_CTX *new_ctx = NULL;
228 int ret = 0;
229
230 if (group->field_data1 == NULL)
231 return 0;
232
233 if (ctx == NULL
234 && (ctx = new_ctx = BN_CTX_secure_new_ex(group->libctx)) == NULL)
235 return 0;
236
237 BN_CTX_start(ctx);
238 if ((e = BN_CTX_get(ctx)) == NULL)
239 goto err;
240
241 /* Inverse in constant time with Fermats Little Theorem */
242 if (!BN_set_word(e, 2))
243 goto err;
244 if (!BN_sub(e, group->field, e))
245 goto err;
246 /*-
247 * Exponent e is public.
248 * No need for scatter-gather or BN_FLG_CONSTTIME.
249 */
250 if (!BN_mod_exp_mont(r, a, e, group->field, ctx, group->field_data1))
251 goto err;
252
253 /* throw an error on zero */
254 if (BN_is_zero(r)) {
255 ERR_raise(ERR_LIB_EC, EC_R_CANNOT_INVERT);
256 goto err;
257 }
258
259 ret = 1;
260
261 err:
262 BN_CTX_end(ctx);
263 BN_CTX_free(new_ctx);
264 return ret;
265 }
266
ossl_ec_GFp_mont_field_encode(const EC_GROUP * group,BIGNUM * r,const BIGNUM * a,BN_CTX * ctx)267 int ossl_ec_GFp_mont_field_encode(const EC_GROUP *group, BIGNUM *r,
268 const BIGNUM *a, BN_CTX *ctx)
269 {
270 if (group->field_data1 == NULL) {
271 ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
272 return 0;
273 }
274
275 return BN_to_montgomery(r, a, (BN_MONT_CTX *)group->field_data1, ctx);
276 }
277
ossl_ec_GFp_mont_field_decode(const EC_GROUP * group,BIGNUM * r,const BIGNUM * a,BN_CTX * ctx)278 int ossl_ec_GFp_mont_field_decode(const EC_GROUP *group, BIGNUM *r,
279 const BIGNUM *a, BN_CTX *ctx)
280 {
281 if (group->field_data1 == NULL) {
282 ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
283 return 0;
284 }
285
286 return BN_from_montgomery(r, a, group->field_data1, ctx);
287 }
288
ossl_ec_GFp_mont_field_set_to_one(const EC_GROUP * group,BIGNUM * r,BN_CTX * ctx)289 int ossl_ec_GFp_mont_field_set_to_one(const EC_GROUP *group, BIGNUM *r,
290 BN_CTX *ctx)
291 {
292 if (group->field_data2 == NULL) {
293 ERR_raise(ERR_LIB_EC, EC_R_NOT_INITIALIZED);
294 return 0;
295 }
296
297 if (!BN_copy(r, group->field_data2))
298 return 0;
299 return 1;
300 }
301
