ecs_ossl.c revision 267654
178344Sobrien/* crypto/ecdsa/ecs_ossl.c */ 278344Sobrien/* 398184Sgordon * Written by Nils Larsch for the OpenSSL project 478344Sobrien */ 578344Sobrien/* ==================================================================== 678344Sobrien * Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved. 778344Sobrien * 898184Sgordon * Redistribution and use in source and binary forms, with or without 9180564Sdougb * modification, are permitted provided that the following conditions 1078344Sobrien * are met: 1178344Sobrien * 1278344Sobrien * 1. Redistributions of source code must retain the above copyright 1378344Sobrien * notice, this list of conditions and the following disclaimer. 14230099Sdougb * 1578344Sobrien * 2. Redistributions in binary form must reproduce the above copyright 1678344Sobrien * notice, this list of conditions and the following disclaimer in 17165664Syar * the documentation and/or other materials provided with the 1878344Sobrien * distribution. 19165664Syar * 20142969Sbrooks * 3. All advertising materials mentioning features or use of this 21142969Sbrooks * software must display the following acknowledgment: 22142969Sbrooks * "This product includes software developed by the OpenSSL Project 23142969Sbrooks * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" 24142969Sbrooks * 25142969Sbrooks * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 2678344Sobrien * endorse or promote products derived from this software without 2778344Sobrien * 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 /* 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 else /* NID_X9_62_characteristic_two_field */ 171 { 172 if (!EC_POINT_get_affine_coordinates_GF2m(group, 173 tmp_point, X, NULL, ctx)) 174 { 175 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB); 176 goto err; 177 } 178 } 179 if (!BN_nnmod(r, X, order, ctx)) 180 { 181 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB); 182 goto err; 183 } 184 } 185 while (BN_is_zero(r)); 186 187 /* compute the inverse of k */ 188 if (!BN_mod_inverse(k, k, order, ctx)) 189 { 190 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB); 191 goto err; 192 } 193 /* clear old values if necessary */ 194 if (*rp != NULL) 195 BN_clear_free(*rp); 196 if (*kinvp != NULL) 197 BN_clear_free(*kinvp); 198 /* save the pre-computed values */ 199 *rp = r; 200 *kinvp = k; 201 ret = 1; 202err: 203 if (!ret) 204 { 205 if (k != NULL) BN_clear_free(k); 206 if (r != NULL) BN_clear_free(r); 207 } 208 if (ctx_in == NULL) 209 BN_CTX_free(ctx); 210 if (order != NULL) 211 BN_free(order); 212 if (tmp_point != NULL) 213 EC_POINT_free(tmp_point); 214 if (X) 215 BN_clear_free(X); 216 return(ret); 217} 218 219 220static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len, 221 const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *eckey) 222{ 223 int ok = 0, i; 224 BIGNUM *kinv=NULL, *s, *m=NULL,*tmp=NULL,*order=NULL; 225 const BIGNUM *ckinv; 226 BN_CTX *ctx = NULL; 227 const EC_GROUP *group; 228 ECDSA_SIG *ret; 229 ECDSA_DATA *ecdsa; 230 const BIGNUM *priv_key; 231 232 ecdsa = ecdsa_check(eckey); 233 group = EC_KEY_get0_group(eckey); 234 priv_key = EC_KEY_get0_private_key(eckey); 235 236 if (group == NULL || priv_key == NULL || ecdsa == NULL) 237 { 238 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER); 239 return NULL; 240 } 241 242 ret = ECDSA_SIG_new(); 243 if (!ret) 244 { 245 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 246 return NULL; 247 } 248 s = ret->s; 249 250 if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL || 251 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL) 252 { 253 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 254 goto err; 255 } 256 257 if (!EC_GROUP_get_order(group, order, ctx)) 258 { 259 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB); 260 goto err; 261 } 262 i = BN_num_bits(order); 263 /* Need to truncate digest if it is too long: first truncate whole 264 * bytes. 265 */ 266 if (8 * dgst_len > i) 267 dgst_len = (i + 7)/8; 268 if (!BN_bin2bn(dgst, dgst_len, m)) 269 { 270 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 271 goto err; 272 } 273 /* If still too long truncate remaining bits with a shift */ 274 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) 275 { 276 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 277 goto err; 278 } 279 do 280 { 281 if (in_kinv == NULL || in_r == NULL) 282 { 283 if (!ECDSA_sign_setup(eckey, ctx, &kinv, &ret->r)) 284 { 285 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,ERR_R_ECDSA_LIB); 286 goto err; 287 } 288 ckinv = kinv; 289 } 290 else 291 { 292 ckinv = in_kinv; 293 if (BN_copy(ret->r, in_r) == NULL) 294 { 295 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE); 296 goto err; 297 } 298 } 299 300 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) 301 { 302 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 303 goto err; 304 } 305 if (!BN_mod_add_quick(s, tmp, m, order)) 306 { 307 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 308 goto err; 309 } 310 if (!BN_mod_mul(s, s, ckinv, order, ctx)) 311 { 312 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB); 313 goto err; 314 } 315 if (BN_is_zero(s)) 316 { 317 /* if kinv and r have been supplied by the caller 318 * don't to generate new kinv and r values */ 319 if (in_kinv != NULL && in_r != NULL) 320 { 321 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ECDSA_R_NEED_NEW_SETUP_VALUES); 322 goto err; 323 } 324 } 325 else 326 /* s != 0 => we have a valid signature */ 327 break; 328 } 329 while (1); 330 331 ok = 1; 332err: 333 if (!ok) 334 { 335 ECDSA_SIG_free(ret); 336 ret = NULL; 337 } 338 if (ctx) 339 BN_CTX_free(ctx); 340 if (m) 341 BN_clear_free(m); 342 if (tmp) 343 BN_clear_free(tmp); 344 if (order) 345 BN_free(order); 346 if (kinv) 347 BN_clear_free(kinv); 348 return ret; 349} 350 351static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len, 352 const ECDSA_SIG *sig, EC_KEY *eckey) 353{ 354 int ret = -1, i; 355 BN_CTX *ctx; 356 BIGNUM *order, *u1, *u2, *m, *X; 357 EC_POINT *point = NULL; 358 const EC_GROUP *group; 359 const EC_POINT *pub_key; 360 361 /* check input values */ 362 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL || 363 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL) 364 { 365 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS); 366 return -1; 367 } 368 369 ctx = BN_CTX_new(); 370 if (!ctx) 371 { 372 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE); 373 return -1; 374 } 375 BN_CTX_start(ctx); 376 order = BN_CTX_get(ctx); 377 u1 = BN_CTX_get(ctx); 378 u2 = BN_CTX_get(ctx); 379 m = BN_CTX_get(ctx); 380 X = BN_CTX_get(ctx); 381 if (!X) 382 { 383 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 384 goto err; 385 } 386 387 if (!EC_GROUP_get_order(group, order, ctx)) 388 { 389 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 390 goto err; 391 } 392 393 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || 394 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) || 395 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0) 396 { 397 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE); 398 ret = 0; /* signature is invalid */ 399 goto err; 400 } 401 /* calculate tmp1 = inv(S) mod order */ 402 if (!BN_mod_inverse(u2, sig->s, order, ctx)) 403 { 404 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 405 goto err; 406 } 407 /* digest -> m */ 408 i = BN_num_bits(order); 409 /* Need to truncate digest if it is too long: first truncate whole 410 * bytes. 411 */ 412 if (8 * dgst_len > i) 413 dgst_len = (i + 7)/8; 414 if (!BN_bin2bn(dgst, dgst_len, m)) 415 { 416 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 417 goto err; 418 } 419 /* If still too long truncate remaining bits with a shift */ 420 if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7))) 421 { 422 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 423 goto err; 424 } 425 /* u1 = m * tmp mod order */ 426 if (!BN_mod_mul(u1, m, u2, order, ctx)) 427 { 428 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 429 goto err; 430 } 431 /* u2 = r * w mod q */ 432 if (!BN_mod_mul(u2, sig->r, u2, order, ctx)) 433 { 434 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 435 goto err; 436 } 437 438 if ((point = EC_POINT_new(group)) == NULL) 439 { 440 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE); 441 goto err; 442 } 443 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx)) 444 { 445 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 446 goto err; 447 } 448 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field) 449 { 450 if (!EC_POINT_get_affine_coordinates_GFp(group, 451 point, X, NULL, ctx)) 452 { 453 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 454 goto err; 455 } 456 } 457 else /* NID_X9_62_characteristic_two_field */ 458 { 459 if (!EC_POINT_get_affine_coordinates_GF2m(group, 460 point, X, NULL, ctx)) 461 { 462 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB); 463 goto err; 464 } 465 } 466 467 if (!BN_nnmod(u1, X, order, ctx)) 468 { 469 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB); 470 goto err; 471 } 472 /* if the signature is correct u1 is equal to sig->r */ 473 ret = (BN_ucmp(u1, sig->r) == 0); 474err: 475 BN_CTX_end(ctx); 476 BN_CTX_free(ctx); 477 if (point) 478 EC_POINT_free(point); 479 return ret; 480} 481