1 /* crypto/ecdsa/ecs_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).
60 #include <openssl/err.h>
61 #include <openssl/obj_mac.h>
62 #include <openssl/bn.h>
63 #include <openssl/rand.h>
65 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen,
66 const BIGNUM *, const BIGNUM *,
68 static int ecdsa_sign_setup_no_digest(EC_KEY *eckey, BN_CTX *ctx_in,
69 BIGNUM **kinvp, BIGNUM **rp);
70 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
71 BIGNUM **rp, const unsigned char *dgst, int dlen);
72 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
73 const ECDSA_SIG *sig, EC_KEY *eckey);
75 static ECDSA_METHOD openssl_ecdsa_meth = {
76 "OpenSSL ECDSA method",
78 ecdsa_sign_setup_no_digest,
84 ECDSA_FLAG_FIPS_METHOD, /* flags */
88 const ECDSA_METHOD *ECDSA_OpenSSL(void)
90 return &openssl_ecdsa_meth;
93 static int ecdsa_sign_setup_no_digest(EC_KEY *eckey,
94 BN_CTX *ctx_in, BIGNUM **kinvp,
97 return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
100 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
101 BIGNUM **kinvp, BIGNUM **rp,
102 const unsigned char *dgst, int dlen)
105 BIGNUM *k = NULL, *r = NULL, *order = NULL, *X = NULL;
106 EC_POINT *tmp_point = NULL;
107 const EC_GROUP *group;
110 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
111 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
115 if (ctx_in == NULL) {
116 if ((ctx = BN_CTX_new()) == NULL) {
117 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
123 k = BN_new(); /* this value is later returned in *kinvp */
124 r = BN_new(); /* this value is later returned in *rp */
127 if (!k || !r || !order || !X) {
128 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
131 if ((tmp_point = EC_POINT_new(group)) == NULL) {
132 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
135 if (!EC_GROUP_get_order(group, order, ctx)) {
136 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
143 #ifndef OPENSSL_NO_SHA512
145 if (!BN_generate_dsa_nonce
146 (k, order, EC_KEY_get0_private_key(eckey), dgst, dlen,
148 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
149 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
155 if (!BN_rand_range(k, order)) {
156 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
157 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
161 while (BN_is_zero(k));
164 * We do not want timing information to leak the length of k, so we
165 * compute G*k using an equivalent scalar of fixed bit-length.
168 if (!BN_add(k, k, order))
170 if (BN_num_bits(k) <= BN_num_bits(order))
171 if (!BN_add(k, k, order))
174 /* compute r the x-coordinate of generator * k */
175 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
176 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
179 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
180 NID_X9_62_prime_field) {
181 if (!EC_POINT_get_affine_coordinates_GFp
182 (group, tmp_point, X, NULL, ctx)) {
183 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
187 #ifndef OPENSSL_NO_EC2M
188 else { /* NID_X9_62_characteristic_two_field */
190 if (!EC_POINT_get_affine_coordinates_GF2m(group,
193 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
198 if (!BN_nnmod(r, X, order, ctx)) {
199 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
203 while (BN_is_zero(r));
205 /* compute the inverse of k */
206 if (EC_GROUP_get_mont_data(group) != NULL) {
208 * We want inverse in constant time, therefore we utilize the fact
209 * order must be prime and use Fermats Little Theorem instead.
211 if (!BN_set_word(X, 2)) {
212 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
215 if (!BN_mod_sub(X, order, X, order, ctx)) {
216 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
219 BN_set_flags(X, BN_FLG_CONSTTIME);
220 if (!BN_mod_exp_mont_consttime
221 (k, k, X, order, ctx, EC_GROUP_get_mont_data(group))) {
222 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
226 if (!BN_mod_inverse(k, k, order, ctx)) {
227 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
232 /* clear old values if necessary */
236 BN_clear_free(*kinvp);
237 /* save the pre-computed values */
252 if (tmp_point != NULL)
253 EC_POINT_free(tmp_point);
259 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
260 const BIGNUM *in_kinv, const BIGNUM *in_r,
264 BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL, *order = NULL;
267 const EC_GROUP *group;
270 const BIGNUM *priv_key;
272 ecdsa = ecdsa_check(eckey);
273 group = EC_KEY_get0_group(eckey);
274 priv_key = EC_KEY_get0_private_key(eckey);
276 if (group == NULL || priv_key == NULL || ecdsa == NULL) {
277 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER);
281 ret = ECDSA_SIG_new();
283 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
288 if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL ||
289 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL) {
290 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
294 if (!EC_GROUP_get_order(group, order, ctx)) {
295 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB);
298 i = BN_num_bits(order);
300 * Need to truncate digest if it is too long: first truncate whole bytes.
302 if (8 * dgst_len > i)
303 dgst_len = (i + 7) / 8;
304 if (!BN_bin2bn(dgst, dgst_len, m)) {
305 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
308 /* If still too long truncate remaining bits with a shift */
309 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
310 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
314 if (in_kinv == NULL || in_r == NULL) {
315 if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len)) {
316 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_ECDSA_LIB);
322 if (BN_copy(ret->r, in_r) == NULL) {
323 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
328 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) {
329 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
332 if (!BN_mod_add_quick(s, tmp, m, order)) {
333 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
336 if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
337 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
342 * if kinv and r have been supplied by the caller don't to
343 * generate new kinv and r values
345 if (in_kinv != NULL && in_r != NULL) {
346 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,
347 ECDSA_R_NEED_NEW_SETUP_VALUES);
351 /* s != 0 => we have a valid signature */
375 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
376 const ECDSA_SIG *sig, EC_KEY *eckey)
380 BIGNUM *order, *u1, *u2, *m, *X;
381 EC_POINT *point = NULL;
382 const EC_GROUP *group;
383 const EC_POINT *pub_key;
385 /* check input values */
386 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
387 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
388 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS);
394 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
398 order = BN_CTX_get(ctx);
399 u1 = BN_CTX_get(ctx);
400 u2 = BN_CTX_get(ctx);
404 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
408 if (!EC_GROUP_get_order(group, order, ctx)) {
409 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
413 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
414 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
415 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
416 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE);
417 ret = 0; /* signature is invalid */
420 /* calculate tmp1 = inv(S) mod order */
421 if (!BN_mod_inverse(u2, sig->s, order, ctx)) {
422 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
426 i = BN_num_bits(order);
428 * Need to truncate digest if it is too long: first truncate whole bytes.
430 if (8 * dgst_len > i)
431 dgst_len = (i + 7) / 8;
432 if (!BN_bin2bn(dgst, dgst_len, m)) {
433 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
436 /* If still too long truncate remaining bits with a shift */
437 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
438 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
441 /* u1 = m * tmp mod order */
442 if (!BN_mod_mul(u1, m, u2, order, ctx)) {
443 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
446 /* u2 = r * w mod q */
447 if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
448 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
452 if ((point = EC_POINT_new(group)) == NULL) {
453 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
456 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
457 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
460 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
461 NID_X9_62_prime_field) {
462 if (!EC_POINT_get_affine_coordinates_GFp(group, point, X, NULL, ctx)) {
463 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
467 #ifndef OPENSSL_NO_EC2M
468 else { /* NID_X9_62_characteristic_two_field */
470 if (!EC_POINT_get_affine_coordinates_GF2m(group, point, X, NULL, ctx)) {
471 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
476 if (!BN_nnmod(u1, X, order, ctx)) {
477 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
480 /* if the signature is correct u1 is equal to sig->r */
481 ret = (BN_ucmp(u1, sig->r) == 0);
486 EC_POINT_free(point);