2 * Copyright 2002-2018 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;
46 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) {
47 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
51 if (!EC_KEY_can_sign(eckey)) {
52 ECerr(EC_F_ECDSA_SIGN_SETUP, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
57 if ((ctx = BN_CTX_new()) == NULL) {
58 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
64 k = BN_new(); /* this value is later returned in *kinvp */
65 r = BN_new(); /* this value is later returned in *rp */
67 if (k == NULL || r == NULL || X == NULL) {
68 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
71 if ((tmp_point = EC_POINT_new(group)) == NULL) {
72 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
75 order = EC_GROUP_get0_order(group);
77 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
81 /* Preallocate space */
82 order_bits = BN_num_bits(order);
83 if (!BN_set_bit(k, order_bits)
84 || !BN_set_bit(r, order_bits)
85 || !BN_set_bit(X, order_bits))
92 if (!BN_generate_dsa_nonce
93 (k, order, EC_KEY_get0_private_key(eckey), dgst, dlen,
95 ECerr(EC_F_ECDSA_SIGN_SETUP,
96 EC_R_RANDOM_NUMBER_GENERATION_FAILED);
100 if (!BN_priv_rand_range(k, order)) {
101 ECerr(EC_F_ECDSA_SIGN_SETUP,
102 EC_R_RANDOM_NUMBER_GENERATION_FAILED);
106 while (BN_is_zero(k));
108 /* compute r the x-coordinate of generator * k */
109 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
110 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
113 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
114 NID_X9_62_prime_field) {
115 if (!EC_POINT_get_affine_coordinates_GFp
116 (group, tmp_point, X, NULL, ctx)) {
117 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
121 #ifndef OPENSSL_NO_EC2M
122 else { /* NID_X9_62_characteristic_two_field */
124 if (!EC_POINT_get_affine_coordinates_GF2m(group,
127 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
132 if (!BN_nnmod(r, X, order, ctx)) {
133 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
137 while (BN_is_zero(r));
139 /* compute the inverse of k */
140 if (!ec_group_do_inverse_ord(group, k, k, ctx)) {
141 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
145 /* clear old values if necessary */
147 BN_clear_free(*kinvp);
148 /* save the pre-computed values */
159 EC_POINT_free(tmp_point);
164 int ossl_ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
167 return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
170 ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
171 const BIGNUM *in_kinv, const BIGNUM *in_r,
175 BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL, *blind = NULL;
176 BIGNUM *blindm = NULL;
177 const BIGNUM *order, *ckinv;
179 const EC_GROUP *group;
181 const BIGNUM *priv_key;
183 group = EC_KEY_get0_group(eckey);
184 priv_key = EC_KEY_get0_private_key(eckey);
186 if (group == NULL || priv_key == NULL) {
187 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_PASSED_NULL_PARAMETER);
191 if (!EC_KEY_can_sign(eckey)) {
192 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
196 ret = ECDSA_SIG_new();
198 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
203 if (ret->r == NULL || ret->s == NULL) {
204 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
209 ctx = BN_CTX_secure_new();
211 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
216 tmp = BN_CTX_get(ctx);
218 blind = BN_CTX_get(ctx);
219 blindm = BN_CTX_get(ctx);
220 if (blindm == NULL) {
221 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
225 order = EC_GROUP_get0_order(group);
227 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_EC_LIB);
230 i = BN_num_bits(order);
232 * Need to truncate digest if it is too long: first truncate whole bytes.
234 if (8 * dgst_len > i)
235 dgst_len = (i + 7) / 8;
236 if (!BN_bin2bn(dgst, dgst_len, m)) {
237 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
240 /* If still too long truncate remaining bits with a shift */
241 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
242 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
246 if (in_kinv == NULL || in_r == NULL) {
247 if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len)) {
248 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_ECDSA_LIB);
254 if (BN_copy(ret->r, in_r) == NULL) {
255 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
261 * The normal signature calculation is:
263 * s := k^-1 * (m + r * priv_key) mod order
265 * We will blind this to protect against side channel attacks
267 * s := blind^-1 * k^-1 * (blind * m + blind * r * priv_key) mod order
270 /* Generate a blinding value */
272 if (!BN_priv_rand(blind, BN_num_bits(order) - 1,
273 BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY))
275 } while (BN_is_zero(blind));
276 BN_set_flags(blind, BN_FLG_CONSTTIME);
277 BN_set_flags(blindm, BN_FLG_CONSTTIME);
278 BN_set_flags(tmp, BN_FLG_CONSTTIME);
280 /* tmp := blind * priv_key * r mod order */
281 if (!BN_mod_mul(tmp, blind, priv_key, order, ctx)) {
282 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
285 if (!BN_mod_mul(tmp, tmp, ret->r, order, ctx)) {
286 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
290 /* blindm := blind * m mod order */
291 if (!BN_mod_mul(blindm, blind, m, order, ctx)) {
292 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
296 /* s : = (blind * priv_key * r) + (blind * m) mod order */
297 if (!BN_mod_add_quick(s, tmp, blindm, order)) {
298 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
302 /* s := s * k^-1 mod order */
303 if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
304 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
308 /* s:= s * blind^-1 mod order */
309 if (BN_mod_inverse(blind, blind, order, ctx) == NULL) {
310 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
313 if (!BN_mod_mul(s, s, blind, order, ctx)) {
314 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
320 * if kinv and r have been supplied by the caller, don't
321 * generate new kinv and r values
323 if (in_kinv != NULL && in_r != NULL) {
324 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_NEED_NEW_SETUP_VALUES);
328 /* s != 0 => we have a valid signature */
348 * 1: correct signature
349 * 0: incorrect signature
352 int ossl_ecdsa_verify(int type, const unsigned char *dgst, int dgst_len,
353 const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)
356 const unsigned char *p = sigbuf;
357 unsigned char *der = NULL;
364 if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
366 /* Ensure signature uses DER and doesn't have trailing garbage */
367 derlen = i2d_ECDSA_SIG(s, &der);
368 if (derlen != sig_len || memcmp(sigbuf, der, derlen) != 0)
370 ret = ECDSA_do_verify(dgst, dgst_len, s, eckey);
372 OPENSSL_clear_free(der, derlen);
377 int ossl_ecdsa_verify_sig(const unsigned char *dgst, int dgst_len,
378 const ECDSA_SIG *sig, EC_KEY *eckey)
383 BIGNUM *u1, *u2, *m, *X;
384 EC_POINT *point = NULL;
385 const EC_GROUP *group;
386 const EC_POINT *pub_key;
388 /* check input values */
389 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
390 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
391 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_MISSING_PARAMETERS);
395 if (!EC_KEY_can_sign(eckey)) {
396 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
402 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
406 u1 = BN_CTX_get(ctx);
407 u2 = BN_CTX_get(ctx);
411 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
415 order = EC_GROUP_get0_order(group);
417 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, 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) {
424 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_BAD_SIGNATURE);
425 ret = 0; /* signature is invalid */
428 /* calculate tmp1 = inv(S) mod order */
429 if (!ec_group_do_inverse_ord(group, u2, sig->s, ctx)) {
430 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
434 i = BN_num_bits(order);
436 * Need to truncate digest if it is too long: first truncate whole bytes.
438 if (8 * dgst_len > i)
439 dgst_len = (i + 7) / 8;
440 if (!BN_bin2bn(dgst, dgst_len, m)) {
441 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
444 /* If still too long truncate remaining bits with a shift */
445 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
446 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
449 /* u1 = m * tmp mod order */
450 if (!BN_mod_mul(u1, m, u2, order, ctx)) {
451 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
454 /* u2 = r * w mod q */
455 if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
456 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
460 if ((point = EC_POINT_new(group)) == NULL) {
461 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
464 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
465 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
468 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
469 NID_X9_62_prime_field) {
470 if (!EC_POINT_get_affine_coordinates_GFp(group, point, X, NULL, ctx)) {
471 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
475 #ifndef OPENSSL_NO_EC2M
476 else { /* NID_X9_62_characteristic_two_field */
478 if (!EC_POINT_get_affine_coordinates_GF2m(group, point, X, NULL, ctx)) {
479 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
484 if (!BN_nnmod(u1, X, order, ctx)) {
485 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
488 /* if the signature is correct u1 is equal to sig->r */
489 ret = (BN_ucmp(u1, sig->r) == 0);
493 EC_POINT_free(point);