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>
64 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen,
65 const BIGNUM *, const BIGNUM *, EC_KEY *eckey);
66 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
68 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
69 const ECDSA_SIG *sig, EC_KEY *eckey);
71 static ECDSA_METHOD openssl_ecdsa_meth = {
72 "OpenSSL ECDSA method",
84 const ECDSA_METHOD *ECDSA_OpenSSL(void)
86 return &openssl_ecdsa_meth;
89 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
93 BIGNUM *k = NULL, *r = NULL, *order = NULL, *X = NULL;
94 EC_POINT *tmp_point=NULL;
95 const EC_GROUP *group;
98 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL)
100 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
106 if ((ctx = BN_CTX_new()) == NULL)
108 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_MALLOC_FAILURE);
115 k = BN_new(); /* this value is later returned in *kinvp */
116 r = BN_new(); /* this value is later returned in *rp */
119 if (!k || !r || !order || !X)
121 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
124 if ((tmp_point = EC_POINT_new(group)) == NULL)
126 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
129 if (!EC_GROUP_get_order(group, order, ctx))
131 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
139 if (!BN_rand_range(k, order))
141 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
142 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
145 while (BN_is_zero(k));
147 /* We do not want timing information to leak the length of k,
148 * so we compute G*k using an equivalent scalar of fixed
151 if (!BN_add(k, k, order)) goto err;
152 if (BN_num_bits(k) <= BN_num_bits(order))
153 if (!BN_add(k, k, order)) goto err;
155 /* compute r the x-coordinate of generator * k */
156 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx))
158 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
161 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
163 if (!EC_POINT_get_affine_coordinates_GFp(group,
164 tmp_point, X, NULL, ctx))
166 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB);
170 #ifndef OPENSSL_NO_EC2M
171 else /* NID_X9_62_characteristic_two_field */
173 if (!EC_POINT_get_affine_coordinates_GF2m(group,
174 tmp_point, X, NULL, ctx))
176 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB);
181 if (!BN_nnmod(r, X, order, ctx))
183 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
187 while (BN_is_zero(r));
189 /* compute the inverse of k */
190 if (EC_GROUP_get_mont_data(group) != NULL)
192 /* We want inverse in constant time, therefore we utilize the
193 * fact order must be prime and use Fermats Little Theorem
195 if (!BN_set_word(X, 2) )
197 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
200 if (!BN_mod_sub(X, order, X, order, ctx))
202 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
205 BN_set_flags(X, BN_FLG_CONSTTIME);
206 if (!BN_mod_exp_mont_consttime(k, k, X, order, ctx, EC_GROUP_get_mont_data(group)))
208 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
214 if (!BN_mod_inverse(k, k, order, ctx))
216 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
221 /* clear old values if necessary */
225 BN_clear_free(*kinvp);
226 /* save the pre-computed values */
233 if (k != NULL) BN_clear_free(k);
234 if (r != NULL) BN_clear_free(r);
240 if (tmp_point != NULL)
241 EC_POINT_free(tmp_point);
248 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
249 const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *eckey)
252 BIGNUM *kinv=NULL, *s, *m=NULL,*tmp=NULL,*order=NULL;
255 const EC_GROUP *group;
258 const BIGNUM *priv_key;
260 ecdsa = ecdsa_check(eckey);
261 group = EC_KEY_get0_group(eckey);
262 priv_key = EC_KEY_get0_private_key(eckey);
264 if (group == NULL || priv_key == NULL || ecdsa == NULL)
266 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER);
270 ret = ECDSA_SIG_new();
273 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
278 if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL ||
279 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL)
281 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
285 if (!EC_GROUP_get_order(group, order, ctx))
287 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB);
290 i = BN_num_bits(order);
291 /* Need to truncate digest if it is too long: first truncate whole
294 if (8 * dgst_len > i)
295 dgst_len = (i + 7)/8;
296 if (!BN_bin2bn(dgst, dgst_len, m))
298 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
301 /* If still too long truncate remaining bits with a shift */
302 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7)))
304 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
309 if (in_kinv == NULL || in_r == NULL)
311 if (!ECDSA_sign_setup(eckey, ctx, &kinv, &ret->r))
313 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,ERR_R_ECDSA_LIB);
321 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))
330 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
333 if (!BN_mod_add_quick(s, tmp, m, order))
335 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
338 if (!BN_mod_mul(s, s, ckinv, order, ctx))
340 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
345 /* if kinv and r have been supplied by the caller
346 * don't to generate new kinv and r values */
347 if (in_kinv != NULL && in_r != NULL)
349 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ECDSA_R_NEED_NEW_SETUP_VALUES);
354 /* s != 0 => we have a valid signature */
379 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
380 const ECDSA_SIG *sig, EC_KEY *eckey)
384 BIGNUM *order, *u1, *u2, *m, *X;
385 EC_POINT *point = NULL;
386 const EC_GROUP *group;
387 const EC_POINT *pub_key;
389 /* check input values */
390 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
391 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL)
393 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS);
400 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
404 order = BN_CTX_get(ctx);
405 u1 = BN_CTX_get(ctx);
406 u2 = BN_CTX_get(ctx);
411 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
415 if (!EC_GROUP_get_order(group, order, ctx))
417 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
421 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
422 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
423 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0)
425 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE);
426 ret = 0; /* signature is invalid */
429 /* calculate tmp1 = inv(S) mod order */
430 if (!BN_mod_inverse(u2, sig->s, order, ctx))
432 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
436 i = BN_num_bits(order);
437 /* Need to truncate digest if it is too long: first truncate whole
440 if (8 * dgst_len > i)
441 dgst_len = (i + 7)/8;
442 if (!BN_bin2bn(dgst, dgst_len, m))
444 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
447 /* If still too long truncate remaining bits with a shift */
448 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7)))
450 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
453 /* u1 = m * tmp mod order */
454 if (!BN_mod_mul(u1, m, u2, order, ctx))
456 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
459 /* u2 = r * w mod q */
460 if (!BN_mod_mul(u2, sig->r, u2, order, ctx))
462 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
466 if ((point = EC_POINT_new(group)) == NULL)
468 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
471 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx))
473 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
476 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
478 if (!EC_POINT_get_affine_coordinates_GFp(group,
479 point, X, NULL, ctx))
481 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
485 #ifndef OPENSSL_NO_EC2M
486 else /* NID_X9_62_characteristic_two_field */
488 if (!EC_POINT_get_affine_coordinates_GF2m(group,
489 point, X, NULL, ctx))
491 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
496 if (!BN_nnmod(u1, X, order, ctx))
498 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
501 /* if the signature is correct u1 is equal to sig->r */
502 ret = (BN_ucmp(u1, sig->r) == 0);
507 EC_POINT_free(point);