1 /* $OpenBSD: ecs_ossl.c,v 1.5 2014/07/12 16:03:37 miod Exp $ */
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/opensslconf.h>
62 #include <openssl/err.h>
63 #include <openssl/obj_mac.h>
64 #include <openssl/bn.h>
66 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen,
67 const BIGNUM *, const BIGNUM *, EC_KEY *eckey);
68 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
70 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
71 const ECDSA_SIG *sig, EC_KEY *eckey);
73 static ECDSA_METHOD openssl_ecdsa_meth = {
74 .name = "OpenSSL ECDSA method",
75 .ecdsa_do_sign = ecdsa_do_sign,
76 .ecdsa_sign_setup = ecdsa_sign_setup,
77 .ecdsa_do_verify = ecdsa_do_verify
83 return &openssl_ecdsa_meth;
87 ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
90 BIGNUM *k = NULL, *r = NULL, *order = NULL, *X = NULL;
91 EC_POINT *tmp_point = NULL;
92 const EC_GROUP *group;
95 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
96 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
100 if (ctx_in == NULL) {
101 if ((ctx = BN_CTX_new()) == NULL) {
102 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
103 ERR_R_MALLOC_FAILURE);
109 k = BN_new(); /* this value is later returned in *kinvp */
110 r = BN_new(); /* this value is later returned in *rp */
113 if (!k || !r || !order || !X) {
114 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
117 if ((tmp_point = EC_POINT_new(group)) == NULL) {
118 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
121 if (!EC_GROUP_get_order(group, order, ctx)) {
122 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
129 if (!BN_rand_range(k, order)) {
130 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
131 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
134 while (BN_is_zero(k));
136 /* We do not want timing information to leak the length of k,
137 * so we compute G*k using an equivalent scalar of fixed
139 if (!BN_add(k, k, order))
141 if (BN_num_bits(k) <= BN_num_bits(order))
142 if (!BN_add(k, k, order))
145 /* compute r the x-coordinate of generator * k */
146 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
147 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
150 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
151 NID_X9_62_prime_field) {
152 if (!EC_POINT_get_affine_coordinates_GFp(group,
153 tmp_point, X, NULL, ctx)) {
154 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
159 #ifndef OPENSSL_NO_EC2M
160 else /* NID_X9_62_characteristic_two_field */
162 if (!EC_POINT_get_affine_coordinates_GF2m(group,
163 tmp_point, X, NULL, ctx)) {
164 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
170 if (!BN_nnmod(r, X, order, ctx)) {
171 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
174 } while (BN_is_zero(r));
176 /* compute the inverse of k */
177 if (!BN_mod_inverse(k, k, order, ctx)) {
178 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
181 /* clear old values if necessary */
183 BN_clear_free(*kinvp);
184 /* save the pre-computed values */
197 EC_POINT_free(tmp_point);
204 ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
205 const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *eckey)
208 BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL, *order = NULL;
211 const EC_GROUP *group;
214 const BIGNUM *priv_key;
216 ecdsa = ecdsa_check(eckey);
217 group = EC_KEY_get0_group(eckey);
218 priv_key = EC_KEY_get0_private_key(eckey);
220 if (group == NULL || priv_key == NULL || ecdsa == NULL) {
221 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER);
225 ret = ECDSA_SIG_new();
227 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
232 if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL ||
233 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL) {
234 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
238 if (!EC_GROUP_get_order(group, order, ctx)) {
239 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB);
242 i = BN_num_bits(order);
243 /* Need to truncate digest if it is too long: first truncate whole
246 if (8 * dgst_len > i)
247 dgst_len = (i + 7)/8;
248 if (!BN_bin2bn(dgst, dgst_len, m)) {
249 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
252 /* If still too long truncate remaining bits with a shift */
253 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
254 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
258 if (in_kinv == NULL || in_r == NULL) {
259 if (!ECDSA_sign_setup(eckey, ctx, &kinv, &ret->r)) {
260 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,
267 if (BN_copy(ret->r, in_r) == NULL) {
268 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,
269 ERR_R_MALLOC_FAILURE);
274 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) {
275 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
278 if (!BN_mod_add_quick(s, tmp, m, order)) {
279 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
282 if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
283 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
287 /* if kinv and r have been supplied by the caller
288 * don't to generate new kinv and r values */
289 if (in_kinv != NULL && in_r != NULL) {
290 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,
291 ECDSA_R_NEED_NEW_SETUP_VALUES);
295 /* s != 0 => we have a valid signature */
315 ecdsa_do_verify(const unsigned char *dgst, int dgst_len, const ECDSA_SIG *sig,
320 BIGNUM *order, *u1, *u2, *m, *X;
321 EC_POINT *point = NULL;
322 const EC_GROUP *group;
323 const EC_POINT *pub_key;
325 /* check input values */
326 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
327 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
328 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS);
334 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
338 order = BN_CTX_get(ctx);
339 u1 = BN_CTX_get(ctx);
340 u2 = BN_CTX_get(ctx);
344 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
348 if (!EC_GROUP_get_order(group, order, ctx)) {
349 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
353 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
354 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
355 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
356 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE);
357 ret = 0; /* signature is invalid */
360 /* calculate tmp1 = inv(S) mod order */
361 if (!BN_mod_inverse(u2, sig->s, order, ctx)) {
362 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
366 i = BN_num_bits(order);
367 /* Need to truncate digest if it is too long: first truncate whole
370 if (8 * dgst_len > i)
371 dgst_len = (i + 7)/8;
372 if (!BN_bin2bn(dgst, dgst_len, m)) {
373 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
376 /* If still too long truncate remaining bits with a shift */
377 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
378 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
381 /* u1 = m * tmp mod order */
382 if (!BN_mod_mul(u1, m, u2, order, ctx)) {
383 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
386 /* u2 = r * w mod q */
387 if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
388 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
392 if ((point = EC_POINT_new(group)) == NULL) {
393 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
396 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
397 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
400 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
401 NID_X9_62_prime_field) {
402 if (!EC_POINT_get_affine_coordinates_GFp(group,
403 point, X, NULL, ctx)) {
404 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
408 #ifndef OPENSSL_NO_EC2M
409 else /* NID_X9_62_characteristic_two_field */
411 if (!EC_POINT_get_affine_coordinates_GF2m(group,
412 point, X, NULL, ctx)) {
413 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
418 if (!BN_nnmod(u1, X, order, ctx)) {
419 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
422 /* if the signature is correct u1 is equal to sig->r */
423 ret = (BN_ucmp(u1, sig->r) == 0);
428 EC_POINT_free(point);