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
,
80 ECDSA_FLAG_FIPS_METHOD
, /* flags */
84 const ECDSA_METHOD
*ECDSA_OpenSSL(void)
86 return &openssl_ecdsa_meth
;
89 static int ecdsa_sign_setup_no_digest(EC_KEY
*eckey
,
90 BN_CTX
*ctx_in
, BIGNUM
**kinvp
,
93 return ecdsa_sign_setup(eckey
, ctx_in
, kinvp
, rp
, NULL
, 0);
96 static int ecdsa_sign_setup(EC_KEY
*eckey
, BN_CTX
*ctx_in
,
97 BIGNUM
**kinvp
, BIGNUM
**rp
,
98 const unsigned char *dgst
, int dlen
)
101 BIGNUM
*k
= NULL
, *r
= NULL
, *order
= NULL
, *X
= NULL
;
102 EC_POINT
*tmp_point
= NULL
;
103 const EC_GROUP
*group
;
106 if (eckey
== NULL
|| (group
= EC_KEY_get0_group(eckey
)) == NULL
) {
107 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_PASSED_NULL_PARAMETER
);
111 if (ctx_in
== NULL
) {
112 if ((ctx
= BN_CTX_new()) == NULL
) {
113 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_MALLOC_FAILURE
);
119 k
= BN_new(); /* this value is later returned in *kinvp */
120 r
= BN_new(); /* this value is later returned in *rp */
123 if (!k
|| !r
|| !order
|| !X
) {
124 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_MALLOC_FAILURE
);
127 if ((tmp_point
= EC_POINT_new(group
)) == NULL
) {
128 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_EC_LIB
);
131 if (!EC_GROUP_get_order(group
, order
, ctx
)) {
132 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_EC_LIB
);
140 if (!BN_generate_dsa_nonce
141 (k
, order
, EC_KEY_get0_private_key(eckey
), dgst
, dlen
,
143 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
,
144 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED
);
148 if (!BN_rand_range(k
, order
)) {
149 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
,
150 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED
);
154 while (BN_is_zero(k
));
157 * We do not want timing information to leak the length of k, so we
158 * compute G*k using an equivalent scalar of fixed bit-length.
161 if (!BN_add(k
, k
, order
))
163 if (BN_num_bits(k
) <= BN_num_bits(order
))
164 if (!BN_add(k
, k
, order
))
167 /* compute r the x-coordinate of generator * k */
168 if (!EC_POINT_mul(group
, tmp_point
, k
, NULL
, NULL
, ctx
)) {
169 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_EC_LIB
);
172 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group
)) ==
173 NID_X9_62_prime_field
) {
174 if (!EC_POINT_get_affine_coordinates_GFp
175 (group
, tmp_point
, X
, NULL
, ctx
)) {
176 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_EC_LIB
);
180 #ifndef OPENSSL_NO_EC2M
181 else { /* NID_X9_62_characteristic_two_field */
183 if (!EC_POINT_get_affine_coordinates_GF2m(group
,
186 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_EC_LIB
);
191 if (!BN_nnmod(r
, X
, order
, ctx
)) {
192 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_BN_LIB
);
196 while (BN_is_zero(r
));
198 /* compute the inverse of k */
199 if (EC_GROUP_get_mont_data(group
) != NULL
) {
201 * We want inverse in constant time, therefore we utilize the fact
202 * order must be prime and use Fermats Little Theorem instead.
204 if (!BN_set_word(X
, 2)) {
205 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_BN_LIB
);
208 if (!BN_mod_sub(X
, order
, X
, order
, ctx
)) {
209 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_BN_LIB
);
212 BN_set_flags(X
, BN_FLG_CONSTTIME
);
213 if (!BN_mod_exp_mont_consttime
214 (k
, k
, X
, order
, ctx
, EC_GROUP_get_mont_data(group
))) {
215 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_BN_LIB
);
219 if (!BN_mod_inverse(k
, k
, order
, ctx
)) {
220 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP
, ERR_R_BN_LIB
);
225 /* clear old values if necessary */
227 BN_clear_free(*kinvp
);
228 /* save the pre-computed values */
240 EC_POINT_free(tmp_point
);
245 static ECDSA_SIG
*ecdsa_do_sign(const unsigned char *dgst
, int dgst_len
,
246 const BIGNUM
*in_kinv
, const BIGNUM
*in_r
,
250 BIGNUM
*kinv
= NULL
, *s
, *m
= NULL
, *tmp
= NULL
, *order
= NULL
;
253 const EC_GROUP
*group
;
256 const BIGNUM
*priv_key
;
258 ecdsa
= ecdsa_check(eckey
);
259 group
= EC_KEY_get0_group(eckey
);
260 priv_key
= EC_KEY_get0_private_key(eckey
);
262 if (group
== NULL
|| priv_key
== NULL
|| ecdsa
== NULL
) {
263 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_PASSED_NULL_PARAMETER
);
267 ret
= ECDSA_SIG_new();
269 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_MALLOC_FAILURE
);
274 if ((ctx
= BN_CTX_new()) == NULL
|| (order
= BN_new()) == NULL
||
275 (tmp
= BN_new()) == NULL
|| (m
= BN_new()) == NULL
) {
276 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_MALLOC_FAILURE
);
280 if (!EC_GROUP_get_order(group
, order
, ctx
)) {
281 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_EC_LIB
);
284 i
= BN_num_bits(order
);
286 * Need to truncate digest if it is too long: first truncate whole bytes.
288 if (8 * dgst_len
> i
)
289 dgst_len
= (i
+ 7) / 8;
290 if (!BN_bin2bn(dgst
, dgst_len
, m
)) {
291 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_BN_LIB
);
294 /* If still too long truncate remaining bits with a shift */
295 if ((8 * dgst_len
> i
) && !BN_rshift(m
, m
, 8 - (i
& 0x7))) {
296 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_BN_LIB
);
300 if (in_kinv
== NULL
|| in_r
== NULL
) {
301 if (!ecdsa_sign_setup(eckey
, ctx
, &kinv
, &ret
->r
, dgst
, dgst_len
)) {
302 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_ECDSA_LIB
);
308 if (BN_copy(ret
->r
, in_r
) == NULL
) {
309 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_MALLOC_FAILURE
);
314 if (!BN_mod_mul(tmp
, priv_key
, ret
->r
, order
, ctx
)) {
315 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_BN_LIB
);
318 if (!BN_mod_add_quick(s
, tmp
, m
, order
)) {
319 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_BN_LIB
);
322 if (!BN_mod_mul(s
, s
, ckinv
, order
, ctx
)) {
323 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
, ERR_R_BN_LIB
);
328 * if kinv and r have been supplied by the caller don't to
329 * generate new kinv and r values
331 if (in_kinv
!= NULL
&& in_r
!= NULL
) {
332 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN
,
333 ECDSA_R_NEED_NEW_SETUP_VALUES
);
337 /* s != 0 => we have a valid signature */
356 static int ecdsa_do_verify(const unsigned char *dgst
, int dgst_len
,
357 const ECDSA_SIG
*sig
, EC_KEY
*eckey
)
361 BIGNUM
*order
, *u1
, *u2
, *m
, *X
;
362 EC_POINT
*point
= NULL
;
363 const EC_GROUP
*group
;
364 const EC_POINT
*pub_key
;
366 /* check input values */
367 if (eckey
== NULL
|| (group
= EC_KEY_get0_group(eckey
)) == NULL
||
368 (pub_key
= EC_KEY_get0_public_key(eckey
)) == NULL
|| sig
== NULL
) {
369 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ECDSA_R_MISSING_PARAMETERS
);
375 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_MALLOC_FAILURE
);
379 order
= BN_CTX_get(ctx
);
380 u1
= BN_CTX_get(ctx
);
381 u2
= BN_CTX_get(ctx
);
385 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_BN_LIB
);
389 if (!EC_GROUP_get_order(group
, order
, ctx
)) {
390 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_EC_LIB
);
394 if (BN_is_zero(sig
->r
) || BN_is_negative(sig
->r
) ||
395 BN_ucmp(sig
->r
, order
) >= 0 || BN_is_zero(sig
->s
) ||
396 BN_is_negative(sig
->s
) || BN_ucmp(sig
->s
, order
) >= 0) {
397 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ECDSA_R_BAD_SIGNATURE
);
398 ret
= 0; /* signature is invalid */
401 /* calculate tmp1 = inv(S) mod order */
402 if (!BN_mod_inverse(u2
, sig
->s
, order
, ctx
)) {
403 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_BN_LIB
);
407 i
= BN_num_bits(order
);
409 * Need to truncate digest if it is too long: first truncate whole bytes.
411 if (8 * dgst_len
> i
)
412 dgst_len
= (i
+ 7) / 8;
413 if (!BN_bin2bn(dgst
, dgst_len
, m
)) {
414 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_BN_LIB
);
417 /* If still too long truncate remaining bits with a shift */
418 if ((8 * dgst_len
> i
) && !BN_rshift(m
, m
, 8 - (i
& 0x7))) {
419 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_BN_LIB
);
422 /* u1 = m * tmp mod order */
423 if (!BN_mod_mul(u1
, m
, u2
, order
, ctx
)) {
424 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_BN_LIB
);
427 /* u2 = r * w mod q */
428 if (!BN_mod_mul(u2
, sig
->r
, u2
, order
, ctx
)) {
429 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_BN_LIB
);
433 if ((point
= EC_POINT_new(group
)) == NULL
) {
434 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_MALLOC_FAILURE
);
437 if (!EC_POINT_mul(group
, point
, u1
, pub_key
, u2
, ctx
)) {
438 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_EC_LIB
);
441 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group
)) ==
442 NID_X9_62_prime_field
) {
443 if (!EC_POINT_get_affine_coordinates_GFp(group
, point
, X
, NULL
, ctx
)) {
444 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_EC_LIB
);
448 #ifndef OPENSSL_NO_EC2M
449 else { /* NID_X9_62_characteristic_two_field */
451 if (!EC_POINT_get_affine_coordinates_GF2m(group
, point
, X
, NULL
, ctx
)) {
452 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_EC_LIB
);
457 if (!BN_nnmod(u1
, X
, order
, ctx
)) {
458 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY
, ERR_R_BN_LIB
);
461 /* if the signature is correct u1 is equal to sig->r */
462 ret
= (BN_ucmp(u1
, sig
->r
) == 0);
466 EC_POINT_free(point
);