Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 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 | |
| 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 | } |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 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 | } |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 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; |
| 202 | err: |
| 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 | |
| 220 | static 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; |
| 332 | err: |
| 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 | |
| 351 | static 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 | } |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 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 | } |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 466 | |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 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); |
| 474 | err: |
| 475 | BN_CTX_end(ctx); |
| 476 | BN_CTX_free(ctx); |
| 477 | if (point) |
| 478 | EC_POINT_free(point); |
| 479 | return ret; |
| 480 | } |