1 /* crypto/ec/ecdsa_ossl.c */
3 * Written by Nils Larsch for the OpenSSL project
5 /* ====================================================================
6 * Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
20 * 3. All advertising materials mentioning features or use of this
21 * software must display the following acknowledgment:
22 * "This product includes software developed by the OpenSSL Project
23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 * endorse or promote products derived from this software without
27 * prior written permission. For written permission, please contact
28 * openssl-core@OpenSSL.org.
30 * 5. Products derived from this software may not be called "OpenSSL"
31 * nor may "OpenSSL" appear in their names without prior written
32 * permission of the OpenSSL Project.
34 * 6. Redistributions of any form whatsoever must retain the following
36 * "This product includes software developed by the OpenSSL Project
37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
53 * This product includes cryptographic software written by Eric Young
54 * (eay@cryptsoft.com). This product includes software written by Tim
55 * Hudson (tjh@cryptsoft.com).
59 #include <openssl/err.h>
60 #include <openssl/obj_mac.h>
61 #include <openssl/bn.h>
62 #include <openssl/rand.h>
63 #include <openssl/ec.h>
66 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
67 BIGNUM **kinvp, BIGNUM **rp,
68 const unsigned char *dgst, int dlen)
71 BIGNUM *k = NULL, *r = NULL, *order = NULL, *X = NULL;
72 EC_POINT *tmp_point = NULL;
73 const EC_GROUP *group;
76 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
77 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
82 if ((ctx = BN_CTX_new()) == NULL) {
83 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
89 k = BN_new(); /* this value is later returned in *kinvp */
90 r = BN_new(); /* this value is later returned in *rp */
93 if (k == NULL || r == NULL || order == NULL || X == NULL) {
94 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
97 if ((tmp_point = EC_POINT_new(group)) == NULL) {
98 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
101 if (!EC_GROUP_get_order(group, order, ctx)) {
102 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
110 if (!BN_generate_dsa_nonce
111 (k, order, EC_KEY_get0_private_key(eckey), dgst, dlen,
113 ECerr(EC_F_ECDSA_SIGN_SETUP,
114 EC_R_RANDOM_NUMBER_GENERATION_FAILED);
118 if (!BN_rand_range(k, order)) {
119 ECerr(EC_F_ECDSA_SIGN_SETUP,
120 EC_R_RANDOM_NUMBER_GENERATION_FAILED);
124 while (BN_is_zero(k));
127 * We do not want timing information to leak the length of k, so we
128 * compute G*k using an equivalent scalar of fixed bit-length.
131 if (!BN_add(k, k, order))
133 if (BN_num_bits(k) <= BN_num_bits(order))
134 if (!BN_add(k, k, order))
137 /* compute r the x-coordinate of generator * k */
138 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
139 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
142 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
143 NID_X9_62_prime_field) {
144 if (!EC_POINT_get_affine_coordinates_GFp
145 (group, tmp_point, X, NULL, ctx)) {
146 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
150 #ifndef OPENSSL_NO_EC2M
151 else { /* NID_X9_62_characteristic_two_field */
153 if (!EC_POINT_get_affine_coordinates_GF2m(group,
156 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
161 if (!BN_nnmod(r, X, order, ctx)) {
162 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
166 while (BN_is_zero(r));
168 /* compute the inverse of k */
169 if (EC_GROUP_get_mont_data(group) != NULL) {
171 * We want inverse in constant time, therefore we utilize the fact
172 * order must be prime and use Fermats Little Theorem instead.
174 if (!BN_set_word(X, 2)) {
175 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
178 if (!BN_mod_sub(X, order, X, order, ctx)) {
179 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
182 BN_set_flags(X, BN_FLG_CONSTTIME);
183 if (!BN_mod_exp_mont_consttime
184 (k, k, X, order, ctx, EC_GROUP_get_mont_data(group))) {
185 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
189 if (!BN_mod_inverse(k, k, order, ctx)) {
190 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
195 /* clear old values if necessary */
197 BN_clear_free(*kinvp);
198 /* save the pre-computed values */
210 EC_POINT_free(tmp_point);
215 int ossl_ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
218 return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
221 ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
222 const BIGNUM *in_kinv, const BIGNUM *in_r,
226 BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL, *order = NULL;
229 const EC_GROUP *group;
231 const BIGNUM *priv_key;
233 group = EC_KEY_get0_group(eckey);
234 priv_key = EC_KEY_get0_private_key(eckey);
236 if (group == NULL || priv_key == NULL) {
237 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_PASSED_NULL_PARAMETER);
241 ret = ECDSA_SIG_new();
243 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
248 if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL ||
249 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL) {
250 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
254 if (!EC_GROUP_get_order(group, order, ctx)) {
255 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_EC_LIB);
258 i = BN_num_bits(order);
260 * Need to truncate digest if it is too long: first truncate whole bytes.
262 if (8 * dgst_len > i)
263 dgst_len = (i + 7) / 8;
264 if (!BN_bin2bn(dgst, dgst_len, m)) {
265 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
268 /* If still too long truncate remaining bits with a shift */
269 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
270 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
274 if (in_kinv == NULL || in_r == NULL) {
275 if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len)) {
276 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_ECDSA_LIB);
282 if (BN_copy(ret->r, in_r) == NULL) {
283 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
288 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) {
289 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
292 if (!BN_mod_add_quick(s, tmp, m, order)) {
293 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
296 if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
297 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
302 * if kinv and r have been supplied by the caller don't to
303 * generate new kinv and r values
305 if (in_kinv != NULL && in_r != NULL) {
306 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_NEED_NEW_SETUP_VALUES);
310 /* s != 0 => we have a valid signature */
329 int ossl_ecdsa_verify_sig(const unsigned char *dgst, int dgst_len,
330 const ECDSA_SIG *sig, EC_KEY *eckey)
334 BIGNUM *order, *u1, *u2, *m, *X;
335 EC_POINT *point = NULL;
336 const EC_GROUP *group;
337 const EC_POINT *pub_key;
339 /* check input values */
340 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
341 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
342 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_MISSING_PARAMETERS);
348 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
352 order = BN_CTX_get(ctx);
353 u1 = BN_CTX_get(ctx);
354 u2 = BN_CTX_get(ctx);
358 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
362 if (!EC_GROUP_get_order(group, order, ctx)) {
363 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
367 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
368 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
369 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
370 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_BAD_SIGNATURE);
371 ret = 0; /* signature is invalid */
374 /* calculate tmp1 = inv(S) mod order */
375 if (!BN_mod_inverse(u2, sig->s, order, ctx)) {
376 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
380 i = BN_num_bits(order);
382 * Need to truncate digest if it is too long: first truncate whole bytes.
384 if (8 * dgst_len > i)
385 dgst_len = (i + 7) / 8;
386 if (!BN_bin2bn(dgst, dgst_len, m)) {
387 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
390 /* If still too long truncate remaining bits with a shift */
391 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
392 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
395 /* u1 = m * tmp mod order */
396 if (!BN_mod_mul(u1, m, u2, order, ctx)) {
397 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
400 /* u2 = r * w mod q */
401 if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
402 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
406 if ((point = EC_POINT_new(group)) == NULL) {
407 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
410 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
411 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
414 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
415 NID_X9_62_prime_field) {
416 if (!EC_POINT_get_affine_coordinates_GFp(group, point, X, NULL, ctx)) {
417 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
421 #ifndef OPENSSL_NO_EC2M
422 else { /* NID_X9_62_characteristic_two_field */
424 if (!EC_POINT_get_affine_coordinates_GF2m(group, point, X, NULL, ctx)) {
425 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
430 if (!BN_nnmod(u1, X, order, ctx)) {
431 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
434 /* if the signature is correct u1 is equal to sig->r */
435 ret = (BN_ucmp(u1, sig->r) == 0);
439 EC_POINT_free(point);