1 /* 2 * Copyright 2017-2023 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 Apache License 2.0 (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 "internal/deprecated.h" 13 14 #include "crypto/sm2.h" 15 #include "crypto/sm2err.h" 16 #include "crypto/ec.h" /* ossl_ec_group_do_inverse_ord() */ 17 #include "internal/numbers.h" 18 #include <openssl/err.h> 19 #include <openssl/evp.h> 20 #include <openssl/err.h> 21 #include <openssl/bn.h> 22 #include <string.h> 23 24 int ossl_sm2_compute_z_digest(uint8_t *out, 25 const EVP_MD *digest, 26 const uint8_t *id, 27 const size_t id_len, 28 const EC_KEY *key) 29 { 30 int rc = 0; 31 const EC_GROUP *group = EC_KEY_get0_group(key); 32 BN_CTX *ctx = NULL; 33 EVP_MD_CTX *hash = NULL; 34 BIGNUM *p = NULL; 35 BIGNUM *a = NULL; 36 BIGNUM *b = NULL; 37 BIGNUM *xG = NULL; 38 BIGNUM *yG = NULL; 39 BIGNUM *xA = NULL; 40 BIGNUM *yA = NULL; 41 int p_bytes = 0; 42 uint8_t *buf = NULL; 43 uint16_t entl = 0; 44 uint8_t e_byte = 0; 45 46 hash = EVP_MD_CTX_new(); 47 ctx = BN_CTX_new_ex(ossl_ec_key_get_libctx(key)); 48 if (hash == NULL || ctx == NULL) { 49 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 50 goto done; 51 } 52 53 p = BN_CTX_get(ctx); 54 a = BN_CTX_get(ctx); 55 b = BN_CTX_get(ctx); 56 xG = BN_CTX_get(ctx); 57 yG = BN_CTX_get(ctx); 58 xA = BN_CTX_get(ctx); 59 yA = BN_CTX_get(ctx); 60 61 if (yA == NULL) { 62 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 63 goto done; 64 } 65 66 if (!EVP_DigestInit(hash, digest)) { 67 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB); 68 goto done; 69 } 70 71 /* Z = h(ENTL || ID || a || b || xG || yG || xA || yA) */ 72 73 if (id_len >= (UINT16_MAX / 8)) { 74 /* too large */ 75 ERR_raise(ERR_LIB_SM2, SM2_R_ID_TOO_LARGE); 76 goto done; 77 } 78 79 entl = (uint16_t)(8 * id_len); 80 81 e_byte = entl >> 8; 82 if (!EVP_DigestUpdate(hash, &e_byte, 1)) { 83 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB); 84 goto done; 85 } 86 e_byte = entl & 0xFF; 87 if (!EVP_DigestUpdate(hash, &e_byte, 1)) { 88 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB); 89 goto done; 90 } 91 92 if (id_len > 0 && !EVP_DigestUpdate(hash, id, id_len)) { 93 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB); 94 goto done; 95 } 96 97 if (!EC_GROUP_get_curve(group, p, a, b, ctx)) { 98 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB); 99 goto done; 100 } 101 102 p_bytes = BN_num_bytes(p); 103 buf = OPENSSL_zalloc(p_bytes); 104 if (buf == NULL) { 105 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 106 goto done; 107 } 108 109 if (BN_bn2binpad(a, buf, p_bytes) < 0 110 || !EVP_DigestUpdate(hash, buf, p_bytes) 111 || BN_bn2binpad(b, buf, p_bytes) < 0 112 || !EVP_DigestUpdate(hash, buf, p_bytes) 113 || !EC_POINT_get_affine_coordinates(group, 114 EC_GROUP_get0_generator(group), 115 xG, yG, ctx) 116 || BN_bn2binpad(xG, buf, p_bytes) < 0 117 || !EVP_DigestUpdate(hash, buf, p_bytes) 118 || BN_bn2binpad(yG, buf, p_bytes) < 0 119 || !EVP_DigestUpdate(hash, buf, p_bytes) 120 || !EC_POINT_get_affine_coordinates(group, 121 EC_KEY_get0_public_key(key), 122 xA, yA, ctx) 123 || BN_bn2binpad(xA, buf, p_bytes) < 0 124 || !EVP_DigestUpdate(hash, buf, p_bytes) 125 || BN_bn2binpad(yA, buf, p_bytes) < 0 126 || !EVP_DigestUpdate(hash, buf, p_bytes) 127 || !EVP_DigestFinal(hash, out, NULL)) { 128 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR); 129 goto done; 130 } 131 132 rc = 1; 133 134 done: 135 OPENSSL_free(buf); 136 BN_CTX_free(ctx); 137 EVP_MD_CTX_free(hash); 138 return rc; 139 } 140 141 static BIGNUM *sm2_compute_msg_hash(const EVP_MD *digest, 142 const EC_KEY *key, 143 const uint8_t *id, 144 const size_t id_len, 145 const uint8_t *msg, size_t msg_len) 146 { 147 EVP_MD_CTX *hash = EVP_MD_CTX_new(); 148 const int md_size = EVP_MD_get_size(digest); 149 uint8_t *z = NULL; 150 BIGNUM *e = NULL; 151 EVP_MD *fetched_digest = NULL; 152 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key); 153 const char *propq = ossl_ec_key_get0_propq(key); 154 155 if (md_size < 0) { 156 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_DIGEST); 157 goto done; 158 } 159 160 z = OPENSSL_zalloc(md_size); 161 if (hash == NULL || z == NULL) { 162 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 163 goto done; 164 } 165 166 fetched_digest = EVP_MD_fetch(libctx, EVP_MD_get0_name(digest), propq); 167 if (fetched_digest == NULL) { 168 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR); 169 goto done; 170 } 171 172 if (!ossl_sm2_compute_z_digest(z, fetched_digest, id, id_len, key)) { 173 /* SM2err already called */ 174 goto done; 175 } 176 177 if (!EVP_DigestInit(hash, fetched_digest) 178 || !EVP_DigestUpdate(hash, z, md_size) 179 || !EVP_DigestUpdate(hash, msg, msg_len) 180 /* reuse z buffer to hold H(Z || M) */ 181 || !EVP_DigestFinal(hash, z, NULL)) { 182 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB); 183 goto done; 184 } 185 186 e = BN_bin2bn(z, md_size, NULL); 187 if (e == NULL) 188 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR); 189 190 done: 191 EVP_MD_free(fetched_digest); 192 OPENSSL_free(z); 193 EVP_MD_CTX_free(hash); 194 return e; 195 } 196 197 static ECDSA_SIG *sm2_sig_gen(const EC_KEY *key, const BIGNUM *e) 198 { 199 const BIGNUM *dA = EC_KEY_get0_private_key(key); 200 const EC_GROUP *group = EC_KEY_get0_group(key); 201 const BIGNUM *order = EC_GROUP_get0_order(group); 202 ECDSA_SIG *sig = NULL; 203 EC_POINT *kG = NULL; 204 BN_CTX *ctx = NULL; 205 BIGNUM *k = NULL; 206 BIGNUM *rk = NULL; 207 BIGNUM *r = NULL; 208 BIGNUM *s = NULL; 209 BIGNUM *x1 = NULL; 210 BIGNUM *tmp = NULL; 211 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key); 212 213 kG = EC_POINT_new(group); 214 ctx = BN_CTX_new_ex(libctx); 215 if (kG == NULL || ctx == NULL) { 216 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 217 goto done; 218 } 219 220 BN_CTX_start(ctx); 221 k = BN_CTX_get(ctx); 222 rk = BN_CTX_get(ctx); 223 x1 = BN_CTX_get(ctx); 224 tmp = BN_CTX_get(ctx); 225 if (tmp == NULL) { 226 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 227 goto done; 228 } 229 230 /* 231 * These values are returned and so should not be allocated out of the 232 * context 233 */ 234 r = BN_new(); 235 s = BN_new(); 236 237 if (r == NULL || s == NULL) { 238 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 239 goto done; 240 } 241 242 /* 243 * A3: Generate a random number k in [1,n-1] using random number generators; 244 * A4: Compute (x1,y1)=[k]G, and convert the type of data x1 to be integer 245 * as specified in clause 4.2.8 of GM/T 0003.1-2012; 246 * A5: Compute r=(e+x1) mod n. If r=0 or r+k=n, then go to A3; 247 * A6: Compute s=(1/(1+dA)*(k-r*dA)) mod n. If s=0, then go to A3; 248 * A7: Convert the type of data (r,s) to be bit strings according to the details 249 * in clause 4.2.2 of GM/T 0003.1-2012. Then the signature of message M is (r,s). 250 */ 251 for (;;) { 252 if (!BN_priv_rand_range_ex(k, order, 0, ctx)) { 253 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR); 254 goto done; 255 } 256 257 if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx) 258 || !EC_POINT_get_affine_coordinates(group, kG, x1, NULL, 259 ctx) 260 || !BN_mod_add(r, e, x1, order, ctx)) { 261 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR); 262 goto done; 263 } 264 265 /* try again if r == 0 or r+k == n */ 266 if (BN_is_zero(r)) 267 continue; 268 269 if (!BN_add(rk, r, k)) { 270 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR); 271 goto done; 272 } 273 274 if (BN_cmp(rk, order) == 0) 275 continue; 276 277 if (!BN_add(s, dA, BN_value_one()) 278 || !ossl_ec_group_do_inverse_ord(group, s, s, ctx) 279 || !BN_mod_mul(tmp, dA, r, order, ctx) 280 || !BN_sub(tmp, k, tmp) 281 || !BN_mod_mul(s, s, tmp, order, ctx)) { 282 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB); 283 goto done; 284 } 285 286 /* try again if s == 0 */ 287 if (BN_is_zero(s)) 288 continue; 289 290 sig = ECDSA_SIG_new(); 291 if (sig == NULL) { 292 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 293 goto done; 294 } 295 296 /* takes ownership of r and s */ 297 ECDSA_SIG_set0(sig, r, s); 298 break; 299 } 300 301 done: 302 if (sig == NULL) { 303 BN_free(r); 304 BN_free(s); 305 } 306 307 BN_CTX_free(ctx); 308 EC_POINT_free(kG); 309 return sig; 310 } 311 312 static int sm2_sig_verify(const EC_KEY *key, const ECDSA_SIG *sig, 313 const BIGNUM *e) 314 { 315 int ret = 0; 316 const EC_GROUP *group = EC_KEY_get0_group(key); 317 const BIGNUM *order = EC_GROUP_get0_order(group); 318 BN_CTX *ctx = NULL; 319 EC_POINT *pt = NULL; 320 BIGNUM *t = NULL; 321 BIGNUM *x1 = NULL; 322 const BIGNUM *r = NULL; 323 const BIGNUM *s = NULL; 324 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key); 325 326 ctx = BN_CTX_new_ex(libctx); 327 pt = EC_POINT_new(group); 328 if (ctx == NULL || pt == NULL) { 329 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 330 goto done; 331 } 332 333 BN_CTX_start(ctx); 334 t = BN_CTX_get(ctx); 335 x1 = BN_CTX_get(ctx); 336 if (x1 == NULL) { 337 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 338 goto done; 339 } 340 341 /* 342 * B1: verify whether r' in [1,n-1], verification failed if not 343 * B2: verify whether s' in [1,n-1], verification failed if not 344 * B3: set M'~=ZA || M' 345 * B4: calculate e'=Hv(M'~) 346 * B5: calculate t = (r' + s') modn, verification failed if t=0 347 * B6: calculate the point (x1', y1')=[s']G + [t]PA 348 * B7: calculate R=(e'+x1') modn, verification pass if yes, otherwise failed 349 */ 350 351 ECDSA_SIG_get0(sig, &r, &s); 352 353 if (BN_cmp(r, BN_value_one()) < 0 354 || BN_cmp(s, BN_value_one()) < 0 355 || BN_cmp(order, r) <= 0 356 || BN_cmp(order, s) <= 0) { 357 ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE); 358 goto done; 359 } 360 361 if (!BN_mod_add(t, r, s, order, ctx)) { 362 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB); 363 goto done; 364 } 365 366 if (BN_is_zero(t)) { 367 ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE); 368 goto done; 369 } 370 371 if (!EC_POINT_mul(group, pt, s, EC_KEY_get0_public_key(key), t, ctx) 372 || !EC_POINT_get_affine_coordinates(group, pt, x1, NULL, ctx)) { 373 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB); 374 goto done; 375 } 376 377 if (!BN_mod_add(t, e, x1, order, ctx)) { 378 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB); 379 goto done; 380 } 381 382 if (BN_cmp(r, t) == 0) 383 ret = 1; 384 385 done: 386 EC_POINT_free(pt); 387 BN_CTX_free(ctx); 388 return ret; 389 } 390 391 ECDSA_SIG *ossl_sm2_do_sign(const EC_KEY *key, 392 const EVP_MD *digest, 393 const uint8_t *id, 394 const size_t id_len, 395 const uint8_t *msg, size_t msg_len) 396 { 397 BIGNUM *e = NULL; 398 ECDSA_SIG *sig = NULL; 399 400 e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len); 401 if (e == NULL) { 402 /* SM2err already called */ 403 goto done; 404 } 405 406 sig = sm2_sig_gen(key, e); 407 408 done: 409 BN_free(e); 410 return sig; 411 } 412 413 int ossl_sm2_do_verify(const EC_KEY *key, 414 const EVP_MD *digest, 415 const ECDSA_SIG *sig, 416 const uint8_t *id, 417 const size_t id_len, 418 const uint8_t *msg, size_t msg_len) 419 { 420 BIGNUM *e = NULL; 421 int ret = 0; 422 423 e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len); 424 if (e == NULL) { 425 /* SM2err already called */ 426 goto done; 427 } 428 429 ret = sm2_sig_verify(key, sig, e); 430 431 done: 432 BN_free(e); 433 return ret; 434 } 435 436 int ossl_sm2_internal_sign(const unsigned char *dgst, int dgstlen, 437 unsigned char *sig, unsigned int *siglen, 438 EC_KEY *eckey) 439 { 440 BIGNUM *e = NULL; 441 ECDSA_SIG *s = NULL; 442 int sigleni; 443 int ret = -1; 444 445 e = BN_bin2bn(dgst, dgstlen, NULL); 446 if (e == NULL) { 447 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB); 448 goto done; 449 } 450 451 s = sm2_sig_gen(eckey, e); 452 if (s == NULL) { 453 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR); 454 goto done; 455 } 456 457 sigleni = i2d_ECDSA_SIG(s, sig != NULL ? &sig : NULL); 458 if (sigleni < 0) { 459 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR); 460 goto done; 461 } 462 *siglen = (unsigned int)sigleni; 463 464 ret = 1; 465 466 done: 467 ECDSA_SIG_free(s); 468 BN_free(e); 469 return ret; 470 } 471 472 int ossl_sm2_internal_verify(const unsigned char *dgst, int dgstlen, 473 const unsigned char *sig, int sig_len, 474 EC_KEY *eckey) 475 { 476 ECDSA_SIG *s = NULL; 477 BIGNUM *e = NULL; 478 const unsigned char *p = sig; 479 unsigned char *der = NULL; 480 int derlen = -1; 481 int ret = -1; 482 483 s = ECDSA_SIG_new(); 484 if (s == NULL) { 485 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE); 486 goto done; 487 } 488 if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL) { 489 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING); 490 goto done; 491 } 492 /* Ensure signature uses DER and doesn't have trailing garbage */ 493 derlen = i2d_ECDSA_SIG(s, &der); 494 if (derlen != sig_len || memcmp(sig, der, derlen) != 0) { 495 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING); 496 goto done; 497 } 498 499 e = BN_bin2bn(dgst, dgstlen, NULL); 500 if (e == NULL) { 501 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB); 502 goto done; 503 } 504 505 ret = sm2_sig_verify(eckey, s, e); 506 507 done: 508 OPENSSL_free(der); 509 BN_free(e); 510 ECDSA_SIG_free(s); 511 return ret; 512 } 513