ecs_ossl.c revision 167612
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@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@cryptsoft.com). This product includes software written by Tim 55 * Hudson (tjh@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 64static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen, 65 const BIGNUM *, const BIGNUM *, EC_KEY *eckey); 66static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, 67 BIGNUM **rp); 68static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len, 69 const ECDSA_SIG *sig, EC_KEY *eckey); 70 71static 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 84const ECDSA_METHOD *ECDSA_OpenSSL(void) 85{ 86 return &openssl_ecdsa_meth; 87} 88 89static 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; 194err: 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 212static 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; 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 if (dgst_len > BN_num_bytes(order)) 255 { 256 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, 257 ECDSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); 258 goto err; 259 } 260 261 if (!BN_bin2bn(dgst, dgst_len, m)) 262 { 263 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 264 goto err; 265 } 266 do 267 { 268 if (in_kinv == NULL || in_r == NULL) 269 { 270 if (!ECDSA_sign_setup(eckey, ctx, &kinv, &ret->r)) 271 { 272 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,ERR_R_ECDSA_LIB); 273 goto err; 274 } 275 ckinv = kinv; 276 } 277 else 278 { 279 ckinv = in_kinv; 280 if (BN_copy(ret->r, in_r) == NULL) 281 { 282 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 283 goto err; 284 } 285 } 286 287 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) 288 { 289 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 290 goto err; 291 } 292 if (!BN_mod_add_quick(s, tmp, m, order)) 293 { 294 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 295 goto err; 296 } 297 if (!BN_mod_mul(s, s, ckinv, order, ctx)) 298 { 299 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 300 goto err; 301 } 302 if (BN_is_zero(s)) 303 { 304 /* if kinv and r have been supplied by the caller 305 * don't to generate new kinv and r values */ 306 if (in_kinv != NULL && in_r != NULL) 307 { 308 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ECDSA_R_NEED_NEW_SETUP_VALUES); 309 goto err; 310 } 311 } 312 else 313 /* s != 0 => we have a valid signature */ 314 break; 315 } 316 while (1); 317 318 ok = 1; 319err: 320 if (!ok) 321 { 322 ECDSA_SIG_free(ret); 323 ret = NULL; 324 } 325 if (ctx) 326 BN_CTX_free(ctx); 327 if (m) 328 BN_clear_free(m); 329 if (tmp) 330 BN_clear_free(tmp); 331 if (order) 332 BN_free(order); 333 if (kinv) 334 BN_clear_free(kinv); 335 return ret; 336} 337 338static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len, 339 const ECDSA_SIG *sig, EC_KEY *eckey) 340{ 341 int ret = -1; 342 BN_CTX *ctx; 343 BIGNUM *order, *u1, *u2, *m, *X; 344 EC_POINT *point = NULL; 345 const EC_GROUP *group; 346 const EC_POINT *pub_key; 347 348 /* check input values */ 349 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL || 350 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) 351 { 352 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS); 353 return -1; 354 } 355 356 ctx = BN_CTX_new(); 357 if (!ctx) 358 { 359 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE); 360 return -1; 361 } 362 BN_CTX_start(ctx); 363 order = BN_CTX_get(ctx); 364 u1 = BN_CTX_get(ctx); 365 u2 = BN_CTX_get(ctx); 366 m = BN_CTX_get(ctx); 367 X = BN_CTX_get(ctx); 368 if (!X) 369 { 370 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 371 goto err; 372 } 373 374 if (!EC_GROUP_get_order(group, order, ctx)) 375 { 376 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 377 goto err; 378 } 379 380 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || 381 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) || 382 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) 383 { 384 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE); 385 ret = 0; /* signature is invalid */ 386 goto err; 387 } 388 /* calculate tmp1 = inv(S) mod order */ 389 if (!BN_mod_inverse(u2, sig->s, order, ctx)) 390 { 391 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 392 goto err; 393 } 394 /* digest -> m */ 395 if (!BN_bin2bn(dgst, dgst_len, m)) 396 { 397 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 398 goto err; 399 } 400 /* u1 = m * tmp mod order */ 401 if (!BN_mod_mul(u1, m, u2, order, ctx)) 402 { 403 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 404 goto err; 405 } 406 /* u2 = r * w mod q */ 407 if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) 408 { 409 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 410 goto err; 411 } 412 413 if ((point = EC_POINT_new(group)) == NULL) 414 { 415 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE); 416 goto err; 417 } 418 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) 419 { 420 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 421 goto err; 422 } 423 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field) 424 { 425 if (!EC_POINT_get_affine_coordinates_GFp(group, 426 point, X, NULL, ctx)) 427 { 428 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 429 goto err; 430 } 431 } 432 else /* NID_X9_62_characteristic_two_field */ 433 { 434 if (!EC_POINT_get_affine_coordinates_GF2m(group, 435 point, X, NULL, ctx)) 436 { 437 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 438 goto err; 439 } 440 } 441 442 if (!BN_nnmod(u1, X, order, ctx)) 443 { 444 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 445 goto err; 446 } 447 /* if the signature is correct u1 is equal to sig->r */ 448 ret = (BN_ucmp(u1, sig->r) == 0); 449err: 450 BN_CTX_end(ctx); 451 BN_CTX_free(ctx); 452 if (point) 453 EC_POINT_free(point); 454 return ret; 455} 456