2 * Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
11 #include <openssl/err.h>
12 #include <openssl/obj_mac.h>
13 #include <openssl/bn.h>
14 #include <openssl/rand.h>
15 #include <openssl/ec.h>
18 int ossl_ecdsa_sign(int type
, const unsigned char *dgst
, int dlen
,
19 unsigned char *sig
, unsigned int *siglen
,
20 const BIGNUM
*kinv
, const BIGNUM
*r
, EC_KEY
*eckey
)
24 s
= ECDSA_do_sign_ex(dgst
, dlen
, kinv
, r
, eckey
);
29 *siglen
= i2d_ECDSA_SIG(s
, &sig
);
34 static int ecdsa_sign_setup(EC_KEY
*eckey
, BN_CTX
*ctx_in
,
35 BIGNUM
**kinvp
, BIGNUM
**rp
,
36 const unsigned char *dgst
, int dlen
)
39 BIGNUM
*k
= NULL
, *r
= NULL
, *X
= NULL
;
41 EC_POINT
*tmp_point
= NULL
;
42 const EC_GROUP
*group
;
45 if (eckey
== NULL
|| (group
= EC_KEY_get0_group(eckey
)) == NULL
) {
46 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_PASSED_NULL_PARAMETER
);
50 if (!EC_KEY_can_sign(eckey
)) {
51 ECerr(EC_F_ECDSA_SIGN_SETUP
, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING
);
56 if ((ctx
= BN_CTX_new()) == NULL
) {
57 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_MALLOC_FAILURE
);
63 k
= BN_new(); /* this value is later returned in *kinvp */
64 r
= BN_new(); /* this value is later returned in *rp */
66 if (k
== NULL
|| r
== NULL
|| X
== NULL
) {
67 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_MALLOC_FAILURE
);
70 if ((tmp_point
= EC_POINT_new(group
)) == NULL
) {
71 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_EC_LIB
);
74 order
= EC_GROUP_get0_order(group
);
76 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_EC_LIB
);
84 if (!BN_generate_dsa_nonce
85 (k
, order
, EC_KEY_get0_private_key(eckey
), dgst
, dlen
,
87 ECerr(EC_F_ECDSA_SIGN_SETUP
,
88 EC_R_RANDOM_NUMBER_GENERATION_FAILED
);
92 if (!BN_rand_range(k
, order
)) {
93 ECerr(EC_F_ECDSA_SIGN_SETUP
,
94 EC_R_RANDOM_NUMBER_GENERATION_FAILED
);
98 while (BN_is_zero(k
));
101 * We do not want timing information to leak the length of k, so we
102 * compute G*k using an equivalent scalar of fixed bit-length.
105 if (!BN_add(k
, k
, order
))
107 if (BN_num_bits(k
) <= BN_num_bits(order
))
108 if (!BN_add(k
, k
, order
))
111 /* compute r the x-coordinate of generator * k */
112 if (!EC_POINT_mul(group
, tmp_point
, k
, NULL
, NULL
, ctx
)) {
113 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_EC_LIB
);
116 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group
)) ==
117 NID_X9_62_prime_field
) {
118 if (!EC_POINT_get_affine_coordinates_GFp
119 (group
, tmp_point
, X
, NULL
, ctx
)) {
120 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_EC_LIB
);
124 #ifndef OPENSSL_NO_EC2M
125 else { /* NID_X9_62_characteristic_two_field */
127 if (!EC_POINT_get_affine_coordinates_GF2m(group
,
130 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_EC_LIB
);
135 if (!BN_nnmod(r
, X
, order
, ctx
)) {
136 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_BN_LIB
);
140 while (BN_is_zero(r
));
142 /* compute the inverse of k */
143 if (EC_GROUP_get_mont_data(group
) != NULL
) {
145 * We want inverse in constant time, therefore we utilize the fact
146 * order must be prime and use Fermats Little Theorem instead.
148 if (!BN_set_word(X
, 2)) {
149 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_BN_LIB
);
152 if (!BN_mod_sub(X
, order
, X
, order
, ctx
)) {
153 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_BN_LIB
);
156 BN_set_flags(X
, BN_FLG_CONSTTIME
);
157 if (!BN_mod_exp_mont_consttime
158 (k
, k
, X
, order
, ctx
, EC_GROUP_get_mont_data(group
))) {
159 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_BN_LIB
);
163 if (!BN_mod_inverse(k
, k
, order
, ctx
)) {
164 ECerr(EC_F_ECDSA_SIGN_SETUP
, ERR_R_BN_LIB
);
169 /* clear old values if necessary */
171 BN_clear_free(*kinvp
);
172 /* save the pre-computed values */
183 EC_POINT_free(tmp_point
);
188 int ossl_ecdsa_sign_setup(EC_KEY
*eckey
, BN_CTX
*ctx_in
, BIGNUM
**kinvp
,
191 return ecdsa_sign_setup(eckey
, ctx_in
, kinvp
, rp
, NULL
, 0);
194 ECDSA_SIG
*ossl_ecdsa_sign_sig(const unsigned char *dgst
, int dgst_len
,
195 const BIGNUM
*in_kinv
, const BIGNUM
*in_r
,
199 BIGNUM
*kinv
= NULL
, *s
, *m
= NULL
, *tmp
= NULL
;
200 const BIGNUM
*order
, *ckinv
;
202 const EC_GROUP
*group
;
204 const BIGNUM
*priv_key
;
206 group
= EC_KEY_get0_group(eckey
);
207 priv_key
= EC_KEY_get0_private_key(eckey
);
209 if (group
== NULL
|| priv_key
== NULL
) {
210 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_PASSED_NULL_PARAMETER
);
214 if (!EC_KEY_can_sign(eckey
)) {
215 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING
);
219 ret
= ECDSA_SIG_new();
221 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_MALLOC_FAILURE
);
226 if (ret
->r
== NULL
|| ret
->s
== NULL
) {
227 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_MALLOC_FAILURE
);
232 if ((ctx
= BN_CTX_new()) == NULL
||
233 (tmp
= BN_new()) == NULL
|| (m
= BN_new()) == NULL
) {
234 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_MALLOC_FAILURE
);
238 order
= EC_GROUP_get0_order(group
);
240 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_EC_LIB
);
243 i
= BN_num_bits(order
);
245 * Need to truncate digest if it is too long: first truncate whole bytes.
247 if (8 * dgst_len
> i
)
248 dgst_len
= (i
+ 7) / 8;
249 if (!BN_bin2bn(dgst
, dgst_len
, m
)) {
250 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_BN_LIB
);
253 /* If still too long truncate remaining bits with a shift */
254 if ((8 * dgst_len
> i
) && !BN_rshift(m
, m
, 8 - (i
& 0x7))) {
255 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_BN_LIB
);
259 if (in_kinv
== NULL
|| in_r
== NULL
) {
260 if (!ecdsa_sign_setup(eckey
, ctx
, &kinv
, &ret
->r
, dgst
, dgst_len
)) {
261 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_ECDSA_LIB
);
267 if (BN_copy(ret
->r
, in_r
) == NULL
) {
268 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_MALLOC_FAILURE
);
273 if (!BN_mod_mul(tmp
, priv_key
, ret
->r
, order
, ctx
)) {
274 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_BN_LIB
);
277 if (!BN_mod_add_quick(s
, tmp
, m
, order
)) {
278 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_BN_LIB
);
281 if (!BN_mod_mul(s
, s
, ckinv
, order
, ctx
)) {
282 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, ERR_R_BN_LIB
);
287 * if kinv and r have been supplied by the caller don't to
288 * generate new kinv and r values
290 if (in_kinv
!= NULL
&& in_r
!= NULL
) {
291 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG
, EC_R_NEED_NEW_SETUP_VALUES
);
295 /* s != 0 => we have a valid signature */
315 * 1: correct signature
316 * 0: incorrect signature
319 int ossl_ecdsa_verify(int type
, const unsigned char *dgst
, int dgst_len
,
320 const unsigned char *sigbuf
, int sig_len
, EC_KEY
*eckey
)
323 const unsigned char *p
= sigbuf
;
324 unsigned char *der
= NULL
;
331 if (d2i_ECDSA_SIG(&s
, &p
, sig_len
) == NULL
)
333 /* Ensure signature uses DER and doesn't have trailing garbage */
334 derlen
= i2d_ECDSA_SIG(s
, &der
);
335 if (derlen
!= sig_len
|| memcmp(sigbuf
, der
, derlen
) != 0)
337 ret
= ECDSA_do_verify(dgst
, dgst_len
, s
, eckey
);
339 OPENSSL_clear_free(der
, derlen
);
344 int ossl_ecdsa_verify_sig(const unsigned char *dgst
, int dgst_len
,
345 const ECDSA_SIG
*sig
, EC_KEY
*eckey
)
350 BIGNUM
*u1
, *u2
, *m
, *X
;
351 EC_POINT
*point
= NULL
;
352 const EC_GROUP
*group
;
353 const EC_POINT
*pub_key
;
355 /* check input values */
356 if (eckey
== NULL
|| (group
= EC_KEY_get0_group(eckey
)) == NULL
||
357 (pub_key
= EC_KEY_get0_public_key(eckey
)) == NULL
|| sig
== NULL
) {
358 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, EC_R_MISSING_PARAMETERS
);
362 if (!EC_KEY_can_sign(eckey
)) {
363 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING
);
369 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_MALLOC_FAILURE
);
373 u1
= BN_CTX_get(ctx
);
374 u2
= BN_CTX_get(ctx
);
378 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_BN_LIB
);
382 order
= EC_GROUP_get0_order(group
);
384 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_EC_LIB
);
388 if (BN_is_zero(sig
->r
) || BN_is_negative(sig
->r
) ||
389 BN_ucmp(sig
->r
, order
) >= 0 || BN_is_zero(sig
->s
) ||
390 BN_is_negative(sig
->s
) || BN_ucmp(sig
->s
, order
) >= 0) {
391 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, EC_R_BAD_SIGNATURE
);
392 ret
= 0; /* signature is invalid */
395 /* calculate tmp1 = inv(S) mod order */
396 if (!BN_mod_inverse(u2
, sig
->s
, order
, ctx
)) {
397 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_BN_LIB
);
401 i
= BN_num_bits(order
);
403 * Need to truncate digest if it is too long: first truncate whole bytes.
405 if (8 * dgst_len
> i
)
406 dgst_len
= (i
+ 7) / 8;
407 if (!BN_bin2bn(dgst
, dgst_len
, m
)) {
408 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_BN_LIB
);
411 /* If still too long truncate remaining bits with a shift */
412 if ((8 * dgst_len
> i
) && !BN_rshift(m
, m
, 8 - (i
& 0x7))) {
413 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_BN_LIB
);
416 /* u1 = m * tmp mod order */
417 if (!BN_mod_mul(u1
, m
, u2
, order
, ctx
)) {
418 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_BN_LIB
);
421 /* u2 = r * w mod q */
422 if (!BN_mod_mul(u2
, sig
->r
, u2
, order
, ctx
)) {
423 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_BN_LIB
);
427 if ((point
= EC_POINT_new(group
)) == NULL
) {
428 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_MALLOC_FAILURE
);
431 if (!EC_POINT_mul(group
, point
, u1
, pub_key
, u2
, ctx
)) {
432 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_EC_LIB
);
435 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group
)) ==
436 NID_X9_62_prime_field
) {
437 if (!EC_POINT_get_affine_coordinates_GFp(group
, point
, X
, NULL
, ctx
)) {
438 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_EC_LIB
);
442 #ifndef OPENSSL_NO_EC2M
443 else { /* NID_X9_62_characteristic_two_field */
445 if (!EC_POINT_get_affine_coordinates_GF2m(group
, point
, X
, NULL
, ctx
)) {
446 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_EC_LIB
);
451 if (!BN_nnmod(u1
, X
, order
, ctx
)) {
452 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG
, ERR_R_BN_LIB
);
455 /* if the signature is correct u1 is equal to sig->r */
456 ret
= (BN_ucmp(u1
, sig
->r
) == 0);
460 EC_POINT_free(point
);