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).
62 #include <openssl/err.h>
63 #include <openssl/obj_mac.h>
64 #include <openssl/bn.h>
65 #include <openssl/rand.h>
67 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen,
68 const BIGNUM *, const BIGNUM *, EC_KEY *eckey);
69 static int ecdsa_sign_setup_no_digest(EC_KEY *eckey,
70 BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
71 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
72 BIGNUM **kinvp, BIGNUM **rp,
73 const unsigned char *dgst, int dlen);
74 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
75 const ECDSA_SIG *sig, EC_KEY *eckey);
77 static ECDSA_METHOD openssl_ecdsa_meth = {
78 "OpenSSL ECDSA method",
80 ecdsa_sign_setup_no_digest,
86 ECDSA_FLAG_FIPS_METHOD, /* flags */
90 const ECDSA_METHOD *ECDSA_OpenSSL(void)
92 return &openssl_ecdsa_meth;
95 static int ecdsa_sign_setup_no_digest(EC_KEY *eckey,
96 BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp) {
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)
112 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
118 if ((ctx = BN_CTX_new()) == NULL)
120 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_MALLOC_FAILURE);
127 k = BN_new(); /* this value is later returned in *kinvp */
128 r = BN_new(); /* this value is later returned in *rp */
131 if (!k || !r || !order || !X)
133 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
136 if ((tmp_point = EC_POINT_new(group)) == NULL)
138 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
141 if (!EC_GROUP_get_order(group, order, ctx))
143 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
151 #ifndef OPENSSL_NO_SHA512
154 if (!BN_generate_dsa_nonce(k, order, EC_KEY_get0_private_key(eckey),
157 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
158 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
165 if (!BN_rand_range(k, order))
167 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
168 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
172 while (BN_is_zero(k));
174 /* We do not want timing information to leak the length of k,
175 * so we compute G*k using an equivalent scalar of fixed
178 if (!BN_add(k, k, order)) goto err;
179 if (BN_num_bits(k) <= BN_num_bits(order))
180 if (!BN_add(k, k, order)) goto err;
182 /* compute r the x-coordinate of generator * k */
183 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx))
185 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
188 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
190 if (!EC_POINT_get_affine_coordinates_GFp(group,
191 tmp_point, X, NULL, ctx))
193 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB);
197 #ifndef OPENSSL_NO_EC2M
198 else /* NID_X9_62_characteristic_two_field */
200 if (!EC_POINT_get_affine_coordinates_GF2m(group,
201 tmp_point, X, NULL, ctx))
203 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB);
208 if (!BN_nnmod(r, X, order, ctx))
210 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
214 while (BN_is_zero(r));
216 /* compute the inverse of k */
217 if (EC_GROUP_get_mont_data(group) != NULL)
219 /* We want inverse in constant time, therefore we utilize the
220 * fact order must be prime and use Fermats Little Theorem
222 if (!BN_set_word(X, 2) )
224 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
227 if (!BN_mod_sub(X, order, X, order, ctx))
229 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
232 BN_set_flags(X, BN_FLG_CONSTTIME);
233 if (!BN_mod_exp_mont_consttime(k, k, X, order, ctx, EC_GROUP_get_mont_data(group)))
235 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
241 if (!BN_mod_inverse(k, k, order, ctx))
243 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
248 /* clear old values if necessary */
252 BN_clear_free(*kinvp);
253 /* save the pre-computed values */
260 if (k != NULL) BN_clear_free(k);
261 if (r != NULL) BN_clear_free(r);
267 if (tmp_point != NULL)
268 EC_POINT_free(tmp_point);
275 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
276 const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *eckey)
279 BIGNUM *kinv=NULL, *s, *m=NULL,*tmp=NULL,*order=NULL;
282 const EC_GROUP *group;
285 const BIGNUM *priv_key;
287 ecdsa = ecdsa_check(eckey);
288 group = EC_KEY_get0_group(eckey);
289 priv_key = EC_KEY_get0_private_key(eckey);
291 if (group == NULL || priv_key == NULL || ecdsa == NULL)
293 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER);
297 ret = ECDSA_SIG_new();
300 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
305 if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL ||
306 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL)
308 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
312 if (!EC_GROUP_get_order(group, order, ctx))
314 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB);
317 i = BN_num_bits(order);
318 /* Need to truncate digest if it is too long: first truncate whole
321 if (8 * dgst_len > i)
322 dgst_len = (i + 7)/8;
323 if (!BN_bin2bn(dgst, dgst_len, m))
325 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
328 /* If still too long truncate remaining bits with a shift */
329 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7)))
331 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
336 if (in_kinv == NULL || in_r == NULL)
338 if (!ecdsa_sign_setup(
339 eckey, ctx, &kinv, &ret->r, dgst, dgst_len))
341 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,ERR_R_ECDSA_LIB);
349 if (BN_copy(ret->r, in_r) == NULL)
351 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
356 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx))
358 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
361 if (!BN_mod_add_quick(s, tmp, m, order))
363 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
366 if (!BN_mod_mul(s, s, ckinv, order, ctx))
368 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
373 /* if kinv and r have been supplied by the caller
374 * don't to generate new kinv and r values */
375 if (in_kinv != NULL && in_r != NULL)
377 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ECDSA_R_NEED_NEW_SETUP_VALUES);
382 /* s != 0 => we have a valid signature */
407 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
408 const ECDSA_SIG *sig, EC_KEY *eckey)
412 BIGNUM *order, *u1, *u2, *m, *X;
413 EC_POINT *point = NULL;
414 const EC_GROUP *group;
415 const EC_POINT *pub_key;
417 /* check input values */
418 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
419 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL)
421 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS);
428 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
432 order = BN_CTX_get(ctx);
433 u1 = BN_CTX_get(ctx);
434 u2 = BN_CTX_get(ctx);
439 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
443 if (!EC_GROUP_get_order(group, order, ctx))
445 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
449 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
450 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
451 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0)
453 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE);
454 ret = 0; /* signature is invalid */
457 /* calculate tmp1 = inv(S) mod order */
458 if (!BN_mod_inverse(u2, sig->s, order, ctx))
460 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
464 i = BN_num_bits(order);
465 /* Need to truncate digest if it is too long: first truncate whole
468 if (8 * dgst_len > i)
469 dgst_len = (i + 7)/8;
470 if (!BN_bin2bn(dgst, dgst_len, m))
472 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
475 /* If still too long truncate remaining bits with a shift */
476 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7)))
478 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
481 /* u1 = m * tmp mod order */
482 if (!BN_mod_mul(u1, m, u2, order, ctx))
484 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
487 /* u2 = r * w mod q */
488 if (!BN_mod_mul(u2, sig->r, u2, order, ctx))
490 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
494 if ((point = EC_POINT_new(group)) == NULL)
496 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
499 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx))
501 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
504 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
506 if (!EC_POINT_get_affine_coordinates_GFp(group,
507 point, X, NULL, ctx))
509 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
513 #ifndef OPENSSL_NO_EC2M
514 else /* NID_X9_62_characteristic_two_field */
516 if (!EC_POINT_get_affine_coordinates_GF2m(group,
517 point, X, NULL, ctx))
519 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
524 if (!BN_nnmod(u1, X, order, ctx))
526 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
529 /* if the signature is correct u1 is equal to sig->r */
530 ret = (BN_ucmp(u1, sig->r) == 0);
535 EC_POINT_free(point);