1 /* crypto/ecdsa/ecs_ossl.c */ 2 /* 3 * Written by Nils Larsch for the OpenSSL project 4 */ 5 /* ==================================================================== 6 * Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 20 * 3. All advertising materials mentioning features or use of this 21 * software must display the following acknowledgment: 22 * "This product includes software developed by the OpenSSL Project 23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" 24 * 25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 26 * endorse or promote products derived from this software without 27 * prior written permission. For written permission, please contact 28 * openssl-core (at) OpenSSL.org. 29 * 30 * 5. Products derived from this software may not be called "OpenSSL" 31 * nor may "OpenSSL" appear in their names without prior written 32 * permission of the OpenSSL Project. 33 * 34 * 6. Redistributions of any form whatsoever must retain the following 35 * acknowledgment: 36 * "This product includes software developed by the OpenSSL Project 37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" 38 * 39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 50 * OF THE POSSIBILITY OF SUCH DAMAGE. 51 * ==================================================================== 52 * 53 * This product includes cryptographic software written by Eric Young 54 * (eay (at) cryptsoft.com). This product includes software written by Tim 55 * Hudson (tjh (at) cryptsoft.com). 56 * 57 */ 58 59 #include "ecs_locl.h" 60 #include <openssl/err.h> 61 #include <openssl/obj_mac.h> 62 #include <openssl/bn.h> 63 64 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen, 65 const BIGNUM *, const BIGNUM *, EC_KEY *eckey); 66 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, 67 BIGNUM **rp); 68 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len, 69 const ECDSA_SIG *sig, EC_KEY *eckey); 70 71 static ECDSA_METHOD openssl_ecdsa_meth = { 72 "OpenSSL ECDSA method", 73 ecdsa_do_sign, 74 ecdsa_sign_setup, 75 ecdsa_do_verify, 76 #if 0 77 NULL, /* init */ 78 NULL, /* finish */ 79 #endif 80 0, /* flags */ 81 NULL /* app_data */ 82 }; 83 84 const ECDSA_METHOD *ECDSA_OpenSSL(void) 85 { 86 return &openssl_ecdsa_meth; 87 } 88 89 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, 90 BIGNUM **rp) 91 { 92 BN_CTX *ctx = NULL; 93 BIGNUM *k = NULL, *r = NULL, *order = NULL, *X = NULL; 94 EC_POINT *tmp_point=NULL; 95 const EC_GROUP *group; 96 int ret = 0; 97 98 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) 99 { 100 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER); 101 return 0; 102 } 103 104 if (ctx_in == NULL) 105 { 106 if ((ctx = BN_CTX_new()) == NULL) 107 { 108 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_MALLOC_FAILURE); 109 return 0; 110 } 111 } 112 else 113 ctx = ctx_in; 114 115 k = BN_new(); /* this value is later returned in *kinvp */ 116 r = BN_new(); /* this value is later returned in *rp */ 117 order = BN_new(); 118 X = BN_new(); 119 if (!k || !r || !order || !X) 120 { 121 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE); 122 goto err; 123 } 124 if ((tmp_point = EC_POINT_new(group)) == NULL) 125 { 126 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB); 127 goto err; 128 } 129 if (!EC_GROUP_get_order(group, order, ctx)) 130 { 131 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB); 132 goto err; 133 } 134 135 do 136 { 137 /* get random k */ 138 do 139 if (!BN_rand_range(k, order)) 140 { 141 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, 142 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED); 143 goto err; 144 } 145 while (BN_is_zero(k)); 146 147 /* We do not want timing information to leak the length of k, 148 * so we compute G*k using an equivalent scalar of fixed 149 * bit-length. */ 150 151 if (!BN_add(k, k, order)) goto err; 152 if (BN_num_bits(k) <= BN_num_bits(order)) 153 if (!BN_add(k, k, order)) goto err; 154 155 /* compute r the x-coordinate of generator * k */ 156 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) 157 { 158 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB); 159 goto err; 160 } 161 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field) 162 { 163 if (!EC_POINT_get_affine_coordinates_GFp(group, 164 tmp_point, X, NULL, ctx)) 165 { 166 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB); 167 goto err; 168 } 169 } 170 #ifndef OPENSSL_NO_EC2M 171 else /* NID_X9_62_characteristic_two_field */ 172 { 173 if (!EC_POINT_get_affine_coordinates_GF2m(group, 174 tmp_point, X, NULL, ctx)) 175 { 176 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB); 177 goto err; 178 } 179 } 180 #endif 181 if (!BN_nnmod(r, X, order, ctx)) 182 { 183 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB); 184 goto err; 185 } 186 } 187 while (BN_is_zero(r)); 188 189 /* compute the inverse of k */ 190 if (!BN_mod_inverse(k, k, order, ctx)) 191 { 192 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB); 193 goto err; 194 } 195 /* clear old values if necessary */ 196 if (*rp != NULL) 197 BN_clear_free(*rp); 198 if (*kinvp != NULL) 199 BN_clear_free(*kinvp); 200 /* save the pre-computed values */ 201 *rp = r; 202 *kinvp = k; 203 ret = 1; 204 err: 205 if (!ret) 206 { 207 if (k != NULL) BN_clear_free(k); 208 if (r != NULL) BN_clear_free(r); 209 } 210 if (ctx_in == NULL) 211 BN_CTX_free(ctx); 212 if (order != NULL) 213 BN_free(order); 214 if (tmp_point != NULL) 215 EC_POINT_free(tmp_point); 216 if (X) 217 BN_clear_free(X); 218 return(ret); 219 } 220 221 222 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len, 223 const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *eckey) 224 { 225 int ok = 0, i; 226 BIGNUM *kinv=NULL, *s, *m=NULL,*tmp=NULL,*order=NULL; 227 const BIGNUM *ckinv; 228 BN_CTX *ctx = NULL; 229 const EC_GROUP *group; 230 ECDSA_SIG *ret; 231 ECDSA_DATA *ecdsa; 232 const BIGNUM *priv_key; 233 234 ecdsa = ecdsa_check(eckey); 235 group = EC_KEY_get0_group(eckey); 236 priv_key = EC_KEY_get0_private_key(eckey); 237 238 if (group == NULL || priv_key == NULL || ecdsa == NULL) 239 { 240 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER); 241 return NULL; 242 } 243 244 ret = ECDSA_SIG_new(); 245 if (!ret) 246 { 247 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 248 return NULL; 249 } 250 s = ret->s; 251 252 if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL || 253 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL) 254 { 255 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 256 goto err; 257 } 258 259 if (!EC_GROUP_get_order(group, order, ctx)) 260 { 261 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB); 262 goto err; 263 } 264 i = BN_num_bits(order); 265 /* Need to truncate digest if it is too long: first truncate whole 266 * bytes. 267 */ 268 if (8 * dgst_len > i) 269 dgst_len = (i + 7)/8; 270 if (!BN_bin2bn(dgst, dgst_len, m)) 271 { 272 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 273 goto err; 274 } 275 /* If still too long truncate remaining bits with a shift */ 276 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) 277 { 278 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 279 goto err; 280 } 281 do 282 { 283 if (in_kinv == NULL || in_r == NULL) 284 { 285 if (!ECDSA_sign_setup(eckey, ctx, &kinv, &ret->r)) 286 { 287 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,ERR_R_ECDSA_LIB); 288 goto err; 289 } 290 ckinv = kinv; 291 } 292 else 293 { 294 ckinv = in_kinv; 295 if (BN_copy(ret->r, in_r) == NULL) 296 { 297 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 298 goto err; 299 } 300 } 301 302 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) 303 { 304 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 305 goto err; 306 } 307 if (!BN_mod_add_quick(s, tmp, m, order)) 308 { 309 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 310 goto err; 311 } 312 if (!BN_mod_mul(s, s, ckinv, order, ctx)) 313 { 314 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 315 goto err; 316 } 317 if (BN_is_zero(s)) 318 { 319 /* if kinv and r have been supplied by the caller 320 * don't to generate new kinv and r values */ 321 if (in_kinv != NULL && in_r != NULL) 322 { 323 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ECDSA_R_NEED_NEW_SETUP_VALUES); 324 goto err; 325 } 326 } 327 else 328 /* s != 0 => we have a valid signature */ 329 break; 330 } 331 while (1); 332 333 ok = 1; 334 err: 335 if (!ok) 336 { 337 ECDSA_SIG_free(ret); 338 ret = NULL; 339 } 340 if (ctx) 341 BN_CTX_free(ctx); 342 if (m) 343 BN_clear_free(m); 344 if (tmp) 345 BN_clear_free(tmp); 346 if (order) 347 BN_free(order); 348 if (kinv) 349 BN_clear_free(kinv); 350 return ret; 351 } 352 353 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len, 354 const ECDSA_SIG *sig, EC_KEY *eckey) 355 { 356 int ret = -1, i; 357 BN_CTX *ctx; 358 BIGNUM *order, *u1, *u2, *m, *X; 359 EC_POINT *point = NULL; 360 const EC_GROUP *group; 361 const EC_POINT *pub_key; 362 363 /* check input values */ 364 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL || 365 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) 366 { 367 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS); 368 return -1; 369 } 370 371 ctx = BN_CTX_new(); 372 if (!ctx) 373 { 374 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE); 375 return -1; 376 } 377 BN_CTX_start(ctx); 378 order = BN_CTX_get(ctx); 379 u1 = BN_CTX_get(ctx); 380 u2 = BN_CTX_get(ctx); 381 m = BN_CTX_get(ctx); 382 X = BN_CTX_get(ctx); 383 if (!X) 384 { 385 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 386 goto err; 387 } 388 389 if (!EC_GROUP_get_order(group, order, ctx)) 390 { 391 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 392 goto err; 393 } 394 395 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || 396 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) || 397 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) 398 { 399 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE); 400 ret = 0; /* signature is invalid */ 401 goto err; 402 } 403 /* calculate tmp1 = inv(S) mod order */ 404 if (!BN_mod_inverse(u2, sig->s, order, ctx)) 405 { 406 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 407 goto err; 408 } 409 /* digest -> m */ 410 i = BN_num_bits(order); 411 /* Need to truncate digest if it is too long: first truncate whole 412 * bytes. 413 */ 414 if (8 * dgst_len > i) 415 dgst_len = (i + 7)/8; 416 if (!BN_bin2bn(dgst, dgst_len, m)) 417 { 418 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 419 goto err; 420 } 421 /* If still too long truncate remaining bits with a shift */ 422 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) 423 { 424 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 425 goto err; 426 } 427 /* u1 = m * tmp mod order */ 428 if (!BN_mod_mul(u1, m, u2, order, ctx)) 429 { 430 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 431 goto err; 432 } 433 /* u2 = r * w mod q */ 434 if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) 435 { 436 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 437 goto err; 438 } 439 440 if ((point = EC_POINT_new(group)) == NULL) 441 { 442 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE); 443 goto err; 444 } 445 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) 446 { 447 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 448 goto err; 449 } 450 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field) 451 { 452 if (!EC_POINT_get_affine_coordinates_GFp(group, 453 point, X, NULL, ctx)) 454 { 455 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 456 goto err; 457 } 458 } 459 #ifndef OPENSSL_NO_EC2M 460 else /* NID_X9_62_characteristic_two_field */ 461 { 462 if (!EC_POINT_get_affine_coordinates_GF2m(group, 463 point, X, NULL, ctx)) 464 { 465 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 466 goto err; 467 } 468 } 469 #endif 470 if (!BN_nnmod(u1, X, order, ctx)) 471 { 472 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 473 goto err; 474 } 475 /* if the signature is correct u1 is equal to sig->r */ 476 ret = (BN_ucmp(u1, sig->r) == 0); 477 err: 478 BN_CTX_end(ctx); 479 BN_CTX_free(ctx); 480 if (point) 481 EC_POINT_free(point); 482 return ret; 483 } 484
