1 /* 2 * Copyright 2017-2019 The OpenSSL Project Authors. All Rights Reserved. 3 * Copyright 2017 Ribose Inc. All Rights Reserved. 4 * Ported from Ribose contributions from Botan. 5 * 6 * Licensed under the OpenSSL license (the "License"). You may not use 7 * this file except in compliance with the License. You can obtain a copy 8 * in the file LICENSE in the source distribution or at 9 * https://www.openssl.org/source/license.html 10 */ 11 12 #include "crypto/sm2.h" 13 #include "crypto/sm2err.h" 14 #include "crypto/ec.h" /* ec_group_do_inverse_ord() */ 15 #include "internal/numbers.h" 16 #include <openssl/err.h> 17 #include <openssl/evp.h> 18 #include <openssl/err.h> 19 #include <openssl/bn.h> 20 #include <string.h> 21 22 int sm2_compute_z_digest(uint8_t *out, 23 const EVP_MD *digest, 24 const uint8_t *id, 25 const size_t id_len, 26 const EC_KEY *key) 27 { 28 int rc = 0; 29 const EC_GROUP *group = EC_KEY_get0_group(key); 30 BN_CTX *ctx = NULL; 31 EVP_MD_CTX *hash = NULL; 32 BIGNUM *p = NULL; 33 BIGNUM *a = NULL; 34 BIGNUM *b = NULL; 35 BIGNUM *xG = NULL; 36 BIGNUM *yG = NULL; 37 BIGNUM *xA = NULL; 38 BIGNUM *yA = NULL; 39 int p_bytes = 0; 40 uint8_t *buf = NULL; 41 uint16_t entl = 0; 42 uint8_t e_byte = 0; 43 44 hash = EVP_MD_CTX_new(); 45 ctx = BN_CTX_new(); 46 if (hash == NULL || ctx == NULL) { 47 SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_MALLOC_FAILURE); 48 goto done; 49 } 50 51 p = BN_CTX_get(ctx); 52 a = BN_CTX_get(ctx); 53 b = BN_CTX_get(ctx); 54 xG = BN_CTX_get(ctx); 55 yG = BN_CTX_get(ctx); 56 xA = BN_CTX_get(ctx); 57 yA = BN_CTX_get(ctx); 58 59 if (yA == NULL) { 60 SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_MALLOC_FAILURE); 61 goto done; 62 } 63 64 if (!EVP_DigestInit(hash, digest)) { 65 SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_EVP_LIB); 66 goto done; 67 } 68 69 /* Z = h(ENTL || ID || a || b || xG || yG || xA || yA) */ 70 71 if (id_len >= (UINT16_MAX / 8)) { 72 /* too large */ 73 SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, SM2_R_ID_TOO_LARGE); 74 goto done; 75 } 76 77 entl = (uint16_t)(8 * id_len); 78 79 e_byte = entl >> 8; 80 if (!EVP_DigestUpdate(hash, &e_byte, 1)) { 81 SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_EVP_LIB); 82 goto done; 83 } 84 e_byte = entl & 0xFF; 85 if (!EVP_DigestUpdate(hash, &e_byte, 1)) { 86 SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_EVP_LIB); 87 goto done; 88 } 89 90 if (id_len > 0 && !EVP_DigestUpdate(hash, id, id_len)) { 91 SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_EVP_LIB); 92 goto done; 93 } 94 95 if (!EC_GROUP_get_curve(group, p, a, b, ctx)) { 96 SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_EC_LIB); 97 goto done; 98 } 99 100 p_bytes = BN_num_bytes(p); 101 buf = OPENSSL_zalloc(p_bytes); 102 if (buf == NULL) { 103 SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_MALLOC_FAILURE); 104 goto done; 105 } 106 107 if (BN_bn2binpad(a, buf, p_bytes) < 0 108 || !EVP_DigestUpdate(hash, buf, p_bytes) 109 || BN_bn2binpad(b, buf, p_bytes) < 0 110 || !EVP_DigestUpdate(hash, buf, p_bytes) 111 || !EC_POINT_get_affine_coordinates(group, 112 EC_GROUP_get0_generator(group), 113 xG, yG, ctx) 114 || BN_bn2binpad(xG, buf, p_bytes) < 0 115 || !EVP_DigestUpdate(hash, buf, p_bytes) 116 || BN_bn2binpad(yG, buf, p_bytes) < 0 117 || !EVP_DigestUpdate(hash, buf, p_bytes) 118 || !EC_POINT_get_affine_coordinates(group, 119 EC_KEY_get0_public_key(key), 120 xA, yA, ctx) 121 || BN_bn2binpad(xA, buf, p_bytes) < 0 122 || !EVP_DigestUpdate(hash, buf, p_bytes) 123 || BN_bn2binpad(yA, buf, p_bytes) < 0 124 || !EVP_DigestUpdate(hash, buf, p_bytes) 125 || !EVP_DigestFinal(hash, out, NULL)) { 126 SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_INTERNAL_ERROR); 127 goto done; 128 } 129 130 rc = 1; 131 132 done: 133 OPENSSL_free(buf); 134 BN_CTX_free(ctx); 135 EVP_MD_CTX_free(hash); 136 return rc; 137 } 138 139 static BIGNUM *sm2_compute_msg_hash(const EVP_MD *digest, 140 const EC_KEY *key, 141 const uint8_t *id, 142 const size_t id_len, 143 const uint8_t *msg, size_t msg_len) 144 { 145 EVP_MD_CTX *hash = EVP_MD_CTX_new(); 146 const int md_size = EVP_MD_size(digest); 147 uint8_t *z = NULL; 148 BIGNUM *e = NULL; 149 150 if (md_size < 0) { 151 SM2err(SM2_F_SM2_COMPUTE_MSG_HASH, SM2_R_INVALID_DIGEST); 152 goto done; 153 } 154 155 z = OPENSSL_zalloc(md_size); 156 if (hash == NULL || z == NULL) { 157 SM2err(SM2_F_SM2_COMPUTE_MSG_HASH, ERR_R_MALLOC_FAILURE); 158 goto done; 159 } 160 161 if (!sm2_compute_z_digest(z, digest, id, id_len, key)) { 162 /* SM2err already called */ 163 goto done; 164 } 165 166 if (!EVP_DigestInit(hash, digest) 167 || !EVP_DigestUpdate(hash, z, md_size) 168 || !EVP_DigestUpdate(hash, msg, msg_len) 169 /* reuse z buffer to hold H(Z || M) */ 170 || !EVP_DigestFinal(hash, z, NULL)) { 171 SM2err(SM2_F_SM2_COMPUTE_MSG_HASH, ERR_R_EVP_LIB); 172 goto done; 173 } 174 175 e = BN_bin2bn(z, md_size, NULL); 176 if (e == NULL) 177 SM2err(SM2_F_SM2_COMPUTE_MSG_HASH, ERR_R_INTERNAL_ERROR); 178 179 done: 180 OPENSSL_free(z); 181 EVP_MD_CTX_free(hash); 182 return e; 183 } 184 185 static ECDSA_SIG *sm2_sig_gen(const EC_KEY *key, const BIGNUM *e) 186 { 187 const BIGNUM *dA = EC_KEY_get0_private_key(key); 188 const EC_GROUP *group = EC_KEY_get0_group(key); 189 const BIGNUM *order = EC_GROUP_get0_order(group); 190 ECDSA_SIG *sig = NULL; 191 EC_POINT *kG = NULL; 192 BN_CTX *ctx = NULL; 193 BIGNUM *k = NULL; 194 BIGNUM *rk = NULL; 195 BIGNUM *r = NULL; 196 BIGNUM *s = NULL; 197 BIGNUM *x1 = NULL; 198 BIGNUM *tmp = NULL; 199 200 kG = EC_POINT_new(group); 201 ctx = BN_CTX_new(); 202 if (kG == NULL || ctx == NULL) { 203 SM2err(SM2_F_SM2_SIG_GEN, ERR_R_MALLOC_FAILURE); 204 goto done; 205 } 206 207 BN_CTX_start(ctx); 208 k = BN_CTX_get(ctx); 209 rk = BN_CTX_get(ctx); 210 x1 = BN_CTX_get(ctx); 211 tmp = BN_CTX_get(ctx); 212 if (tmp == NULL) { 213 SM2err(SM2_F_SM2_SIG_GEN, ERR_R_MALLOC_FAILURE); 214 goto done; 215 } 216 217 /* 218 * These values are returned and so should not be allocated out of the 219 * context 220 */ 221 r = BN_new(); 222 s = BN_new(); 223 224 if (r == NULL || s == NULL) { 225 SM2err(SM2_F_SM2_SIG_GEN, ERR_R_MALLOC_FAILURE); 226 goto done; 227 } 228 229 for (;;) { 230 if (!BN_priv_rand_range(k, order)) { 231 SM2err(SM2_F_SM2_SIG_GEN, ERR_R_INTERNAL_ERROR); 232 goto done; 233 } 234 235 if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx) 236 || !EC_POINT_get_affine_coordinates(group, kG, x1, NULL, 237 ctx) 238 || !BN_mod_add(r, e, x1, order, ctx)) { 239 SM2err(SM2_F_SM2_SIG_GEN, ERR_R_INTERNAL_ERROR); 240 goto done; 241 } 242 243 /* try again if r == 0 or r+k == n */ 244 if (BN_is_zero(r)) 245 continue; 246 247 if (!BN_add(rk, r, k)) { 248 SM2err(SM2_F_SM2_SIG_GEN, ERR_R_INTERNAL_ERROR); 249 goto done; 250 } 251 252 if (BN_cmp(rk, order) == 0) 253 continue; 254 255 if (!BN_add(s, dA, BN_value_one()) 256 || !ec_group_do_inverse_ord(group, s, s, ctx) 257 || !BN_mod_mul(tmp, dA, r, order, ctx) 258 || !BN_sub(tmp, k, tmp) 259 || !BN_mod_mul(s, s, tmp, order, ctx)) { 260 SM2err(SM2_F_SM2_SIG_GEN, ERR_R_BN_LIB); 261 goto done; 262 } 263 264 sig = ECDSA_SIG_new(); 265 if (sig == NULL) { 266 SM2err(SM2_F_SM2_SIG_GEN, ERR_R_MALLOC_FAILURE); 267 goto done; 268 } 269 270 /* takes ownership of r and s */ 271 ECDSA_SIG_set0(sig, r, s); 272 break; 273 } 274 275 done: 276 if (sig == NULL) { 277 BN_free(r); 278 BN_free(s); 279 } 280 281 BN_CTX_free(ctx); 282 EC_POINT_free(kG); 283 return sig; 284 } 285 286 static int sm2_sig_verify(const EC_KEY *key, const ECDSA_SIG *sig, 287 const BIGNUM *e) 288 { 289 int ret = 0; 290 const EC_GROUP *group = EC_KEY_get0_group(key); 291 const BIGNUM *order = EC_GROUP_get0_order(group); 292 BN_CTX *ctx = NULL; 293 EC_POINT *pt = NULL; 294 BIGNUM *t = NULL; 295 BIGNUM *x1 = NULL; 296 const BIGNUM *r = NULL; 297 const BIGNUM *s = NULL; 298 299 ctx = BN_CTX_new(); 300 pt = EC_POINT_new(group); 301 if (ctx == NULL || pt == NULL) { 302 SM2err(SM2_F_SM2_SIG_VERIFY, ERR_R_MALLOC_FAILURE); 303 goto done; 304 } 305 306 BN_CTX_start(ctx); 307 t = BN_CTX_get(ctx); 308 x1 = BN_CTX_get(ctx); 309 if (x1 == NULL) { 310 SM2err(SM2_F_SM2_SIG_VERIFY, ERR_R_MALLOC_FAILURE); 311 goto done; 312 } 313 314 /* 315 * B1: verify whether r' in [1,n-1], verification failed if not 316 * B2: verify whether s' in [1,n-1], verification failed if not 317 * B3: set M'~=ZA || M' 318 * B4: calculate e'=Hv(M'~) 319 * B5: calculate t = (r' + s') modn, verification failed if t=0 320 * B6: calculate the point (x1', y1')=[s']G + [t]PA 321 * B7: calculate R=(e'+x1') modn, verification pass if yes, otherwise failed 322 */ 323 324 ECDSA_SIG_get0(sig, &r, &s); 325 326 if (BN_cmp(r, BN_value_one()) < 0 327 || BN_cmp(s, BN_value_one()) < 0 328 || BN_cmp(order, r) <= 0 329 || BN_cmp(order, s) <= 0) { 330 SM2err(SM2_F_SM2_SIG_VERIFY, SM2_R_BAD_SIGNATURE); 331 goto done; 332 } 333 334 if (!BN_mod_add(t, r, s, order, ctx)) { 335 SM2err(SM2_F_SM2_SIG_VERIFY, ERR_R_BN_LIB); 336 goto done; 337 } 338 339 if (BN_is_zero(t)) { 340 SM2err(SM2_F_SM2_SIG_VERIFY, SM2_R_BAD_SIGNATURE); 341 goto done; 342 } 343 344 if (!EC_POINT_mul(group, pt, s, EC_KEY_get0_public_key(key), t, ctx) 345 || !EC_POINT_get_affine_coordinates(group, pt, x1, NULL, ctx)) { 346 SM2err(SM2_F_SM2_SIG_VERIFY, ERR_R_EC_LIB); 347 goto done; 348 } 349 350 if (!BN_mod_add(t, e, x1, order, ctx)) { 351 SM2err(SM2_F_SM2_SIG_VERIFY, ERR_R_BN_LIB); 352 goto done; 353 } 354 355 if (BN_cmp(r, t) == 0) 356 ret = 1; 357 358 done: 359 EC_POINT_free(pt); 360 BN_CTX_free(ctx); 361 return ret; 362 } 363 364 ECDSA_SIG *sm2_do_sign(const EC_KEY *key, 365 const EVP_MD *digest, 366 const uint8_t *id, 367 const size_t id_len, 368 const uint8_t *msg, size_t msg_len) 369 { 370 BIGNUM *e = NULL; 371 ECDSA_SIG *sig = NULL; 372 373 e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len); 374 if (e == NULL) { 375 /* SM2err already called */ 376 goto done; 377 } 378 379 sig = sm2_sig_gen(key, e); 380 381 done: 382 BN_free(e); 383 return sig; 384 } 385 386 int sm2_do_verify(const EC_KEY *key, 387 const EVP_MD *digest, 388 const ECDSA_SIG *sig, 389 const uint8_t *id, 390 const size_t id_len, 391 const uint8_t *msg, size_t msg_len) 392 { 393 BIGNUM *e = NULL; 394 int ret = 0; 395 396 e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len); 397 if (e == NULL) { 398 /* SM2err already called */ 399 goto done; 400 } 401 402 ret = sm2_sig_verify(key, sig, e); 403 404 done: 405 BN_free(e); 406 return ret; 407 } 408 409 int sm2_sign(const unsigned char *dgst, int dgstlen, 410 unsigned char *sig, unsigned int *siglen, EC_KEY *eckey) 411 { 412 BIGNUM *e = NULL; 413 ECDSA_SIG *s = NULL; 414 int sigleni; 415 int ret = -1; 416 417 e = BN_bin2bn(dgst, dgstlen, NULL); 418 if (e == NULL) { 419 SM2err(SM2_F_SM2_SIGN, ERR_R_BN_LIB); 420 goto done; 421 } 422 423 s = sm2_sig_gen(eckey, e); 424 425 sigleni = i2d_ECDSA_SIG(s, &sig); 426 if (sigleni < 0) { 427 SM2err(SM2_F_SM2_SIGN, ERR_R_INTERNAL_ERROR); 428 goto done; 429 } 430 *siglen = (unsigned int)sigleni; 431 432 ret = 1; 433 434 done: 435 ECDSA_SIG_free(s); 436 BN_free(e); 437 return ret; 438 } 439 440 int sm2_verify(const unsigned char *dgst, int dgstlen, 441 const unsigned char *sig, int sig_len, EC_KEY *eckey) 442 { 443 ECDSA_SIG *s = NULL; 444 BIGNUM *e = NULL; 445 const unsigned char *p = sig; 446 unsigned char *der = NULL; 447 int derlen = -1; 448 int ret = -1; 449 450 s = ECDSA_SIG_new(); 451 if (s == NULL) { 452 SM2err(SM2_F_SM2_VERIFY, ERR_R_MALLOC_FAILURE); 453 goto done; 454 } 455 if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL) { 456 SM2err(SM2_F_SM2_VERIFY, SM2_R_INVALID_ENCODING); 457 goto done; 458 } 459 /* Ensure signature uses DER and doesn't have trailing garbage */ 460 derlen = i2d_ECDSA_SIG(s, &der); 461 if (derlen != sig_len || memcmp(sig, der, derlen) != 0) { 462 SM2err(SM2_F_SM2_VERIFY, SM2_R_INVALID_ENCODING); 463 goto done; 464 } 465 466 e = BN_bin2bn(dgst, dgstlen, NULL); 467 if (e == NULL) { 468 SM2err(SM2_F_SM2_VERIFY, ERR_R_BN_LIB); 469 goto done; 470 } 471 472 ret = sm2_sig_verify(eckey, s, e); 473 474 done: 475 OPENSSL_free(der); 476 BN_free(e); 477 ECDSA_SIG_free(s); 478 return ret; 479 } 480