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/rand.h>
14 #include "internal/bn_int.h"
17 int ossl_ecdsa_sign(int type, const unsigned char *dgst, int dlen,
18 unsigned char *sig, unsigned int *siglen,
19 const BIGNUM *kinv, const BIGNUM *r, EC_KEY *eckey)
23 s = ECDSA_do_sign_ex(dgst, dlen, kinv, r, eckey);
28 *siglen = i2d_ECDSA_SIG(s, &sig);
33 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
34 BIGNUM **kinvp, BIGNUM **rp,
35 const unsigned char *dgst, int dlen)
38 BIGNUM *k = NULL, *r = NULL, *X = NULL;
40 EC_POINT *tmp_point = NULL;
41 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);
55 if ((ctx = ctx_in) == NULL) {
56 if ((ctx = BN_CTX_new()) == NULL) {
57 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
62 k = BN_new(); /* this value is later returned in *kinvp */
63 r = BN_new(); /* this value is later returned in *rp */
65 if (k == NULL || r == NULL || X == NULL) {
66 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
69 if ((tmp_point = EC_POINT_new(group)) == NULL) {
70 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
73 order = EC_GROUP_get0_order(group);
75 /* Preallocate space */
76 order_bits = BN_num_bits(order);
77 if (!BN_set_bit(k, order_bits)
78 || !BN_set_bit(r, order_bits)
79 || !BN_set_bit(X, order_bits))
86 if (!BN_generate_dsa_nonce(k, order,
87 EC_KEY_get0_private_key(eckey),
89 ECerr(EC_F_ECDSA_SIGN_SETUP,
90 EC_R_RANDOM_NUMBER_GENERATION_FAILED);
94 if (!BN_priv_rand_range(k, order)) {
95 ECerr(EC_F_ECDSA_SIGN_SETUP,
96 EC_R_RANDOM_NUMBER_GENERATION_FAILED);
100 } while (BN_is_zero(k));
102 /* compute r the x-coordinate of generator * k */
103 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
104 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
107 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
108 NID_X9_62_prime_field) {
109 if (!EC_POINT_get_affine_coordinates_GFp(group, tmp_point, X,
111 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
115 #ifndef OPENSSL_NO_EC2M
116 else { /* NID_X9_62_characteristic_two_field */
117 if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp_point, X,
119 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
124 if (!BN_nnmod(r, X, order, ctx)) {
125 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
128 } while (BN_is_zero(r));
130 /* compute the inverse of k */
131 if (!ec_group_do_inverse_ord(group, k, k, ctx)) {
132 ECerr(EC_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
136 /* clear old values if necessary */
138 BN_clear_free(*kinvp);
139 /* save the pre-computed values */
150 EC_POINT_free(tmp_point);
155 int ossl_ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
158 return ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
161 ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
162 const BIGNUM *in_kinv, const BIGNUM *in_r,
166 BIGNUM *kinv = NULL, *s, *m = NULL;
167 const BIGNUM *order, *ckinv;
169 const EC_GROUP *group;
171 const BIGNUM *priv_key;
173 group = EC_KEY_get0_group(eckey);
174 priv_key = EC_KEY_get0_private_key(eckey);
176 if (group == NULL || priv_key == NULL) {
177 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_PASSED_NULL_PARAMETER);
181 if (!EC_KEY_can_sign(eckey)) {
182 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
186 ret = ECDSA_SIG_new();
188 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
193 if (ret->r == NULL || ret->s == NULL) {
194 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
199 if ((ctx = BN_CTX_new()) == NULL
200 || (m = BN_new()) == NULL) {
201 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
205 order = EC_GROUP_get0_order(group);
206 i = BN_num_bits(order);
208 * Need to truncate digest if it is too long: first truncate whole bytes.
210 if (8 * dgst_len > i)
211 dgst_len = (i + 7) / 8;
212 if (!BN_bin2bn(dgst, dgst_len, m)) {
213 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
216 /* If still too long, truncate remaining bits with a shift */
217 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
218 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
222 if (in_kinv == NULL || in_r == NULL) {
223 if (!ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len)) {
224 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_ECDSA_LIB);
230 if (BN_copy(ret->r, in_r) == NULL) {
231 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
237 * With only one multiplicant being in Montgomery domain
238 * multiplication yields real result without post-conversion.
239 * Also note that all operations but last are performed with
240 * zero-padded vectors. Last operation, BN_mod_mul_montgomery
241 * below, returns user-visible value with removed zero padding.
243 if (!bn_to_mont_fixed_top(s, ret->r, group->mont_data, ctx)
244 || !bn_mul_mont_fixed_top(s, s, priv_key, group->mont_data, ctx)) {
245 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
248 if (!bn_mod_add_fixed_top(s, s, m, order)) {
249 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
253 * |s| can still be larger than modulus, because |m| can be. In
254 * such case we count on Montgomery reduction to tie it up.
256 if (!bn_to_mont_fixed_top(s, s, group->mont_data, ctx)
257 || !BN_mod_mul_montgomery(s, s, ckinv, group->mont_data, ctx)) {
258 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
264 * if kinv and r have been supplied by the caller, don't
265 * generate new kinv and r values
267 if (in_kinv != NULL && in_r != NULL) {
268 ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, EC_R_NEED_NEW_SETUP_VALUES);
272 /* s != 0 => we have a valid signature */
291 * 1: correct signature
292 * 0: incorrect signature
295 int ossl_ecdsa_verify(int type, const unsigned char *dgst, int dgst_len,
296 const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)
299 const unsigned char *p = sigbuf;
300 unsigned char *der = NULL;
307 if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL)
309 /* Ensure signature uses DER and doesn't have trailing garbage */
310 derlen = i2d_ECDSA_SIG(s, &der);
311 if (derlen != sig_len || memcmp(sigbuf, der, derlen) != 0)
313 ret = ECDSA_do_verify(dgst, dgst_len, s, eckey);
315 OPENSSL_clear_free(der, derlen);
320 int ossl_ecdsa_verify_sig(const unsigned char *dgst, int dgst_len,
321 const ECDSA_SIG *sig, EC_KEY *eckey)
326 BIGNUM *u1, *u2, *m, *X;
327 EC_POINT *point = NULL;
328 const EC_GROUP *group;
329 const EC_POINT *pub_key;
331 /* check input values */
332 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
333 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) {
334 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_MISSING_PARAMETERS);
338 if (!EC_KEY_can_sign(eckey)) {
339 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_CURVE_DOES_NOT_SUPPORT_SIGNING);
345 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
349 u1 = BN_CTX_get(ctx);
350 u2 = BN_CTX_get(ctx);
354 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
358 order = EC_GROUP_get0_order(group);
360 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
364 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
365 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
366 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) {
367 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, EC_R_BAD_SIGNATURE);
368 ret = 0; /* signature is invalid */
371 /* calculate tmp1 = inv(S) mod order */
372 if (!ec_group_do_inverse_ord(group, u2, sig->s, ctx)) {
373 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
377 i = BN_num_bits(order);
379 * Need to truncate digest if it is too long: first truncate whole bytes.
381 if (8 * dgst_len > i)
382 dgst_len = (i + 7) / 8;
383 if (!BN_bin2bn(dgst, dgst_len, m)) {
384 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
387 /* If still too long truncate remaining bits with a shift */
388 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) {
389 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
392 /* u1 = m * tmp mod order */
393 if (!BN_mod_mul(u1, m, u2, order, ctx)) {
394 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
397 /* u2 = r * w mod q */
398 if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) {
399 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
403 if ((point = EC_POINT_new(group)) == NULL) {
404 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_MALLOC_FAILURE);
407 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) {
408 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
411 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
412 NID_X9_62_prime_field) {
413 if (!EC_POINT_get_affine_coordinates_GFp(group, point, X, NULL, ctx)) {
414 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
418 #ifndef OPENSSL_NO_EC2M
419 else { /* NID_X9_62_characteristic_two_field */
421 if (!EC_POINT_get_affine_coordinates_GF2m(group, point, X, NULL, ctx)) {
422 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_EC_LIB);
427 if (!BN_nnmod(u1, X, order, ctx)) {
428 ECerr(EC_F_OSSL_ECDSA_VERIFY_SIG, ERR_R_BN_LIB);
431 /* if the signature is correct u1 is equal to sig->r */
432 ret = (BN_ucmp(u1, sig->r) == 0);
436 EC_POINT_free(point);