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 /* compute r the x-coordinate of generator * k */ 148 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) 149 { 150 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB); 151 goto err; 152 } 153 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field) 154 { 155 if (!EC_POINT_get_affine_coordinates_GFp(group, 156 tmp_point, X, NULL, ctx)) 157 { 158 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB); 159 goto err; 160 } 161 } 162 else /* NID_X9_62_characteristic_two_field */ 163 { 164 if (!EC_POINT_get_affine_coordinates_GF2m(group, 165 tmp_point, X, NULL, ctx)) 166 { 167 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB); 168 goto err; 169 } 170 } 171 if (!BN_nnmod(r, X, order, ctx)) 172 { 173 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB); 174 goto err; 175 } 176 } 177 while (BN_is_zero(r)); 178 179 /* compute the inverse of k */ 180 if (!BN_mod_inverse(k, k, order, ctx)) 181 { 182 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB); 183 goto err; 184 } 185 /* clear old values if necessary */ 186 if (*rp != NULL) 187 BN_clear_free(*rp); 188 if (*kinvp != NULL) 189 BN_clear_free(*kinvp); 190 /* save the pre-computed values */ 191 *rp = r; 192 *kinvp = k; 193 ret = 1; 194 err: 195 if (!ret) 196 { 197 if (k != NULL) BN_clear_free(k); 198 if (r != NULL) BN_clear_free(r); 199 } 200 if (ctx_in == NULL) 201 BN_CTX_free(ctx); 202 if (order != NULL) 203 BN_free(order); 204 if (tmp_point != NULL) 205 EC_POINT_free(tmp_point); 206 if (X) 207 BN_clear_free(X); 208 return(ret); 209 } 210 211 212 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len, 213 const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *eckey) 214 { 215 int ok = 0, i; 216 BIGNUM *kinv=NULL, *s, *m=NULL,*tmp=NULL,*order=NULL; 217 const BIGNUM *ckinv; 218 BN_CTX *ctx = NULL; 219 const EC_GROUP *group; 220 ECDSA_SIG *ret; 221 ECDSA_DATA *ecdsa; 222 const BIGNUM *priv_key; 223 224 ecdsa = ecdsa_check(eckey); 225 group = EC_KEY_get0_group(eckey); 226 priv_key = EC_KEY_get0_private_key(eckey); 227 228 if (group == NULL || priv_key == NULL || ecdsa == NULL) 229 { 230 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER); 231 return NULL; 232 } 233 234 ret = ECDSA_SIG_new(); 235 if (!ret) 236 { 237 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 238 return NULL; 239 } 240 s = ret->s; 241 242 if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL || 243 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL) 244 { 245 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 246 goto err; 247 } 248 249 if (!EC_GROUP_get_order(group, order, ctx)) 250 { 251 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB); 252 goto err; 253 } 254 i = BN_num_bits(order); 255 /* Need to truncate digest if it is too long: first truncate whole 256 * bytes. 257 */ 258 if (8 * dgst_len > i) 259 dgst_len = (i + 7)/8; 260 if (!BN_bin2bn(dgst, dgst_len, m)) 261 { 262 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 263 goto err; 264 } 265 /* If still too long truncate remaining bits with a shift */ 266 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) 267 { 268 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 269 goto err; 270 } 271 do 272 { 273 if (in_kinv == NULL || in_r == NULL) 274 { 275 if (!ECDSA_sign_setup(eckey, ctx, &kinv, &ret->r)) 276 { 277 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,ERR_R_ECDSA_LIB); 278 goto err; 279 } 280 ckinv = kinv; 281 } 282 else 283 { 284 ckinv = in_kinv; 285 if (BN_copy(ret->r, in_r) == NULL) 286 { 287 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 288 goto err; 289 } 290 } 291 292 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) 293 { 294 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 295 goto err; 296 } 297 if (!BN_mod_add_quick(s, tmp, m, order)) 298 { 299 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 300 goto err; 301 } 302 if (!BN_mod_mul(s, s, ckinv, order, ctx)) 303 { 304 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 305 goto err; 306 } 307 if (BN_is_zero(s)) 308 { 309 /* if kinv and r have been supplied by the caller 310 * don't to generate new kinv and r values */ 311 if (in_kinv != NULL && in_r != NULL) 312 { 313 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ECDSA_R_NEED_NEW_SETUP_VALUES); 314 goto err; 315 } 316 } 317 else 318 /* s != 0 => we have a valid signature */ 319 break; 320 } 321 while (1); 322 323 ok = 1; 324 err: 325 if (!ok) 326 { 327 ECDSA_SIG_free(ret); 328 ret = NULL; 329 } 330 if (ctx) 331 BN_CTX_free(ctx); 332 if (m) 333 BN_clear_free(m); 334 if (tmp) 335 BN_clear_free(tmp); 336 if (order) 337 BN_free(order); 338 if (kinv) 339 BN_clear_free(kinv); 340 return ret; 341 } 342 343 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len, 344 const ECDSA_SIG *sig, EC_KEY *eckey) 345 { 346 int ret = -1, i; 347 BN_CTX *ctx; 348 BIGNUM *order, *u1, *u2, *m, *X; 349 EC_POINT *point = NULL; 350 const EC_GROUP *group; 351 const EC_POINT *pub_key; 352 353 /* check input values */ 354 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL || 355 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) 356 { 357 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS); 358 return -1; 359 } 360 361 ctx = BN_CTX_new(); 362 if (!ctx) 363 { 364 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE); 365 return -1; 366 } 367 BN_CTX_start(ctx); 368 order = BN_CTX_get(ctx); 369 u1 = BN_CTX_get(ctx); 370 u2 = BN_CTX_get(ctx); 371 m = BN_CTX_get(ctx); 372 X = BN_CTX_get(ctx); 373 if (!X) 374 { 375 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 376 goto err; 377 } 378 379 if (!EC_GROUP_get_order(group, order, ctx)) 380 { 381 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 382 goto err; 383 } 384 385 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || 386 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) || 387 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) 388 { 389 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE); 390 ret = 0; /* signature is invalid */ 391 goto err; 392 } 393 /* calculate tmp1 = inv(S) mod order */ 394 if (!BN_mod_inverse(u2, sig->s, order, ctx)) 395 { 396 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 397 goto err; 398 } 399 /* digest -> m */ 400 i = BN_num_bits(order); 401 /* Need to truncate digest if it is too long: first truncate whole 402 * bytes. 403 */ 404 if (8 * dgst_len > i) 405 dgst_len = (i + 7)/8; 406 if (!BN_bin2bn(dgst, dgst_len, m)) 407 { 408 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 409 goto err; 410 } 411 /* If still too long truncate remaining bits with a shift */ 412 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) 413 { 414 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 415 goto err; 416 } 417 /* u1 = m * tmp mod order */ 418 if (!BN_mod_mul(u1, m, u2, order, ctx)) 419 { 420 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 421 goto err; 422 } 423 /* u2 = r * w mod q */ 424 if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) 425 { 426 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 427 goto err; 428 } 429 430 if ((point = EC_POINT_new(group)) == NULL) 431 { 432 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE); 433 goto err; 434 } 435 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) 436 { 437 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 438 goto err; 439 } 440 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field) 441 { 442 if (!EC_POINT_get_affine_coordinates_GFp(group, 443 point, X, NULL, ctx)) 444 { 445 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 446 goto err; 447 } 448 } 449 else /* NID_X9_62_characteristic_two_field */ 450 { 451 if (!EC_POINT_get_affine_coordinates_GF2m(group, 452 point, X, NULL, ctx)) 453 { 454 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 455 goto err; 456 } 457 } 458 459 if (!BN_nnmod(u1, X, order, ctx)) 460 { 461 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 462 goto err; 463 } 464 /* if the signature is correct u1 is equal to sig->r */ 465 ret = (BN_ucmp(u1, sig->r) == 0); 466 err: 467 BN_CTX_end(ctx); 468 BN_CTX_free(ctx); 469 if (point) 470 EC_POINT_free(point); 471 return ret; 472 } 473
