1 /* $OpenBSD: rsa_eay.c,v 1.48 2017/04/28 22:46:40 beck Exp $ */ 2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 3 * All rights reserved. 4 * 5 * This package is an SSL implementation written 6 * by Eric Young (eay@cryptsoft.com). 7 * The implementation was written so as to conform with Netscapes SSL. 8 * 9 * This library is free for commercial and non-commercial use as long as 10 * the following conditions are aheared to. The following conditions 11 * apply to all code found in this distribution, be it the RC4, RSA, 12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 13 * included with this distribution is covered by the same copyright terms 14 * except that the holder is Tim Hudson (tjh@cryptsoft.com). 15 * 16 * Copyright remains Eric Young's, and as such any Copyright notices in 17 * the code are not to be removed. 18 * If this package is used in a product, Eric Young should be given attribution 19 * as the author of the parts of the library used. 20 * This can be in the form of a textual message at program startup or 21 * in documentation (online or textual) provided with the package. 22 * 23 * Redistribution and use in source and binary forms, with or without 24 * modification, are permitted provided that the following conditions 25 * are met: 26 * 1. Redistributions of source code must retain the copyright 27 * notice, this list of conditions and the following disclaimer. 28 * 2. Redistributions in binary form must reproduce the above copyright 29 * notice, this list of conditions and the following disclaimer in the 30 * documentation and/or other materials provided with the distribution. 31 * 3. All advertising materials mentioning features or use of this software 32 * must display the following acknowledgement: 33 * "This product includes cryptographic software written by 34 * Eric Young (eay@cryptsoft.com)" 35 * The word 'cryptographic' can be left out if the rouines from the library 36 * being used are not cryptographic related :-). 37 * 4. If you include any Windows specific code (or a derivative thereof) from 38 * the apps directory (application code) you must include an acknowledgement: 39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40 * 41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 51 * SUCH DAMAGE. 52 * 53 * The licence and distribution terms for any publically available version or 54 * derivative of this code cannot be changed. i.e. this code cannot simply be 55 * copied and put under another distribution licence 56 * [including the GNU Public Licence.] 57 */ 58 /* ==================================================================== 59 * Copyright (c) 1998-2006 The OpenSSL Project. All rights reserved. 60 * 61 * Redistribution and use in source and binary forms, with or without 62 * modification, are permitted provided that the following conditions 63 * are met: 64 * 65 * 1. Redistributions of source code must retain the above copyright 66 * notice, this list of conditions and the following disclaimer. 67 * 68 * 2. Redistributions in binary form must reproduce the above copyright 69 * notice, this list of conditions and the following disclaimer in 70 * the documentation and/or other materials provided with the 71 * distribution. 72 * 73 * 3. All advertising materials mentioning features or use of this 74 * software must display the following acknowledgment: 75 * "This product includes software developed by the OpenSSL Project 76 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 77 * 78 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 79 * endorse or promote products derived from this software without 80 * prior written permission. For written permission, please contact 81 * openssl-core@openssl.org. 82 * 83 * 5. Products derived from this software may not be called "OpenSSL" 84 * nor may "OpenSSL" appear in their names without prior written 85 * permission of the OpenSSL Project. 86 * 87 * 6. Redistributions of any form whatsoever must retain the following 88 * acknowledgment: 89 * "This product includes software developed by the OpenSSL Project 90 * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 91 * 92 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 93 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 94 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 95 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 96 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 97 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 98 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 99 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 100 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 101 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 102 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 103 * OF THE POSSIBILITY OF SUCH DAMAGE. 104 * ==================================================================== 105 * 106 * This product includes cryptographic software written by Eric Young 107 * (eay@cryptsoft.com). This product includes software written by Tim 108 * Hudson (tjh@cryptsoft.com). 109 * 110 */ 111 112 #include <stdio.h> 113 #include <string.h> 114 115 #include <openssl/opensslconf.h> 116 117 #include <openssl/bn.h> 118 #include <openssl/err.h> 119 #include <openssl/rsa.h> 120 121 #include "bn_lcl.h" 122 123 static int RSA_eay_public_encrypt(int flen, const unsigned char *from, 124 unsigned char *to, RSA *rsa, int padding); 125 static int RSA_eay_private_encrypt(int flen, const unsigned char *from, 126 unsigned char *to, RSA *rsa, int padding); 127 static int RSA_eay_public_decrypt(int flen, const unsigned char *from, 128 unsigned char *to, RSA *rsa, int padding); 129 static int RSA_eay_private_decrypt(int flen, const unsigned char *from, 130 unsigned char *to, RSA *rsa, int padding); 131 static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa, BN_CTX *ctx); 132 static int RSA_eay_init(RSA *rsa); 133 static int RSA_eay_finish(RSA *rsa); 134 135 static RSA_METHOD rsa_pkcs1_eay_meth = { 136 .name = "Eric Young's PKCS#1 RSA", 137 .rsa_pub_enc = RSA_eay_public_encrypt, 138 .rsa_pub_dec = RSA_eay_public_decrypt, /* signature verification */ 139 .rsa_priv_enc = RSA_eay_private_encrypt, /* signing */ 140 .rsa_priv_dec = RSA_eay_private_decrypt, 141 .rsa_mod_exp = RSA_eay_mod_exp, 142 .bn_mod_exp = BN_mod_exp_mont_ct, /* XXX probably we should not use Montgomery if e == 3 */ 143 .init = RSA_eay_init, 144 .finish = RSA_eay_finish, 145 }; 146 147 const RSA_METHOD * 148 RSA_PKCS1_SSLeay(void) 149 { 150 return &rsa_pkcs1_eay_meth; 151 } 152 153 static int 154 RSA_eay_public_encrypt(int flen, const unsigned char *from, unsigned char *to, 155 RSA *rsa, int padding) 156 { 157 BIGNUM *f, *ret; 158 int i, j, k, num = 0, r = -1; 159 unsigned char *buf = NULL; 160 BN_CTX *ctx = NULL; 161 162 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) { 163 RSAerror(RSA_R_MODULUS_TOO_LARGE); 164 return -1; 165 } 166 167 if (BN_ucmp(rsa->n, rsa->e) <= 0) { 168 RSAerror(RSA_R_BAD_E_VALUE); 169 return -1; 170 } 171 172 /* for large moduli, enforce exponent limit */ 173 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) { 174 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) { 175 RSAerror(RSA_R_BAD_E_VALUE); 176 return -1; 177 } 178 } 179 180 if ((ctx = BN_CTX_new()) == NULL) 181 goto err; 182 183 BN_CTX_start(ctx); 184 f = BN_CTX_get(ctx); 185 ret = BN_CTX_get(ctx); 186 num = BN_num_bytes(rsa->n); 187 buf = malloc(num); 188 189 if (f == NULL || ret == NULL || buf == NULL) { 190 RSAerror(ERR_R_MALLOC_FAILURE); 191 goto err; 192 } 193 194 switch (padding) { 195 case RSA_PKCS1_PADDING: 196 i = RSA_padding_add_PKCS1_type_2(buf, num, from, flen); 197 break; 198 #ifndef OPENSSL_NO_SHA 199 case RSA_PKCS1_OAEP_PADDING: 200 i = RSA_padding_add_PKCS1_OAEP(buf, num, from, flen, NULL, 0); 201 break; 202 #endif 203 case RSA_SSLV23_PADDING: 204 i = RSA_padding_add_SSLv23(buf, num, from, flen); 205 break; 206 case RSA_NO_PADDING: 207 i = RSA_padding_add_none(buf, num, from, flen); 208 break; 209 default: 210 RSAerror(RSA_R_UNKNOWN_PADDING_TYPE); 211 goto err; 212 } 213 if (i <= 0) 214 goto err; 215 216 if (BN_bin2bn(buf, num, f) == NULL) 217 goto err; 218 219 if (BN_ucmp(f, rsa->n) >= 0) { 220 /* usually the padding functions would catch this */ 221 RSAerror(RSA_R_DATA_TOO_LARGE_FOR_MODULUS); 222 goto err; 223 } 224 225 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC) 226 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, 227 CRYPTO_LOCK_RSA, rsa->n, ctx)) 228 goto err; 229 230 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx, 231 rsa->_method_mod_n)) 232 goto err; 233 234 /* put in leading 0 bytes if the number is less than the 235 * length of the modulus */ 236 j = BN_num_bytes(ret); 237 i = BN_bn2bin(ret, &(to[num - j])); 238 for (k = 0; k < num - i; k++) 239 to[k] = 0; 240 241 r = num; 242 err: 243 if (ctx != NULL) { 244 BN_CTX_end(ctx); 245 BN_CTX_free(ctx); 246 } 247 if (buf != NULL) { 248 explicit_bzero(buf, num); 249 free(buf); 250 } 251 return r; 252 } 253 254 static BN_BLINDING * 255 rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx) 256 { 257 BN_BLINDING *ret; 258 int got_write_lock = 0; 259 CRYPTO_THREADID cur; 260 261 CRYPTO_r_lock(CRYPTO_LOCK_RSA); 262 263 if (rsa->blinding == NULL) { 264 CRYPTO_r_unlock(CRYPTO_LOCK_RSA); 265 CRYPTO_w_lock(CRYPTO_LOCK_RSA); 266 got_write_lock = 1; 267 268 if (rsa->blinding == NULL) 269 rsa->blinding = RSA_setup_blinding(rsa, ctx); 270 } 271 272 ret = rsa->blinding; 273 if (ret == NULL) 274 goto err; 275 276 CRYPTO_THREADID_current(&cur); 277 if (!CRYPTO_THREADID_cmp(&cur, BN_BLINDING_thread_id(ret))) { 278 /* rsa->blinding is ours! */ 279 *local = 1; 280 } else { 281 /* resort to rsa->mt_blinding instead */ 282 /* 283 * Instruct rsa_blinding_convert(), rsa_blinding_invert() 284 * that the BN_BLINDING is shared, meaning that accesses 285 * require locks, and that the blinding factor must be 286 * stored outside the BN_BLINDING 287 */ 288 *local = 0; 289 290 if (rsa->mt_blinding == NULL) { 291 if (!got_write_lock) { 292 CRYPTO_r_unlock(CRYPTO_LOCK_RSA); 293 CRYPTO_w_lock(CRYPTO_LOCK_RSA); 294 got_write_lock = 1; 295 } 296 297 if (rsa->mt_blinding == NULL) 298 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx); 299 } 300 ret = rsa->mt_blinding; 301 } 302 303 err: 304 if (got_write_lock) 305 CRYPTO_w_unlock(CRYPTO_LOCK_RSA); 306 else 307 CRYPTO_r_unlock(CRYPTO_LOCK_RSA); 308 return ret; 309 } 310 311 static int 312 rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind, BN_CTX *ctx) 313 { 314 if (unblind == NULL) 315 /* 316 * Local blinding: store the unblinding factor 317 * in BN_BLINDING. 318 */ 319 return BN_BLINDING_convert_ex(f, NULL, b, ctx); 320 else { 321 /* 322 * Shared blinding: store the unblinding factor 323 * outside BN_BLINDING. 324 */ 325 int ret; 326 CRYPTO_w_lock(CRYPTO_LOCK_RSA_BLINDING); 327 ret = BN_BLINDING_convert_ex(f, unblind, b, ctx); 328 CRYPTO_w_unlock(CRYPTO_LOCK_RSA_BLINDING); 329 return ret; 330 } 331 } 332 333 static int 334 rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind, BN_CTX *ctx) 335 { 336 /* 337 * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex 338 * will use the unblinding factor stored in BN_BLINDING. 339 * If BN_BLINDING is shared between threads, unblind must be non-null: 340 * BN_BLINDING_invert_ex will then use the local unblinding factor, 341 * and will only read the modulus from BN_BLINDING. 342 * In both cases it's safe to access the blinding without a lock. 343 */ 344 return BN_BLINDING_invert_ex(f, unblind, b, ctx); 345 } 346 347 /* signing */ 348 static int 349 RSA_eay_private_encrypt(int flen, const unsigned char *from, unsigned char *to, 350 RSA *rsa, int padding) 351 { 352 BIGNUM *f, *ret, *res; 353 int i, j, k, num = 0, r = -1; 354 unsigned char *buf = NULL; 355 BN_CTX *ctx = NULL; 356 int local_blinding = 0; 357 /* 358 * Used only if the blinding structure is shared. A non-NULL unblind 359 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store 360 * the unblinding factor outside the blinding structure. 361 */ 362 BIGNUM *unblind = NULL; 363 BN_BLINDING *blinding = NULL; 364 365 if ((ctx = BN_CTX_new()) == NULL) 366 goto err; 367 368 BN_CTX_start(ctx); 369 f = BN_CTX_get(ctx); 370 ret = BN_CTX_get(ctx); 371 num = BN_num_bytes(rsa->n); 372 buf = malloc(num); 373 374 if (f == NULL || ret == NULL || buf == NULL) { 375 RSAerror(ERR_R_MALLOC_FAILURE); 376 goto err; 377 } 378 379 switch (padding) { 380 case RSA_PKCS1_PADDING: 381 i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen); 382 break; 383 case RSA_X931_PADDING: 384 i = RSA_padding_add_X931(buf, num, from, flen); 385 break; 386 case RSA_NO_PADDING: 387 i = RSA_padding_add_none(buf, num, from, flen); 388 break; 389 case RSA_SSLV23_PADDING: 390 default: 391 RSAerror(RSA_R_UNKNOWN_PADDING_TYPE); 392 goto err; 393 } 394 if (i <= 0) 395 goto err; 396 397 if (BN_bin2bn(buf, num, f) == NULL) 398 goto err; 399 400 if (BN_ucmp(f, rsa->n) >= 0) { 401 /* usually the padding functions would catch this */ 402 RSAerror(RSA_R_DATA_TOO_LARGE_FOR_MODULUS); 403 goto err; 404 } 405 406 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) { 407 blinding = rsa_get_blinding(rsa, &local_blinding, ctx); 408 if (blinding == NULL) { 409 RSAerror(ERR_R_INTERNAL_ERROR); 410 goto err; 411 } 412 } 413 414 if (blinding != NULL) { 415 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) { 416 RSAerror(ERR_R_MALLOC_FAILURE); 417 goto err; 418 } 419 if (!rsa_blinding_convert(blinding, f, unblind, ctx)) 420 goto err; 421 } 422 423 if ((rsa->flags & RSA_FLAG_EXT_PKEY) || 424 (rsa->p != NULL && rsa->q != NULL && rsa->dmp1 != NULL && 425 rsa->dmq1 != NULL && rsa->iqmp != NULL)) { 426 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx)) 427 goto err; 428 } else { 429 BIGNUM d; 430 431 BN_init(&d); 432 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME); 433 434 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC) 435 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, 436 CRYPTO_LOCK_RSA, rsa->n, ctx)) 437 goto err; 438 439 if (!rsa->meth->bn_mod_exp(ret, f, &d, rsa->n, ctx, 440 rsa->_method_mod_n)) { 441 goto err; 442 } 443 } 444 445 if (blinding) 446 if (!rsa_blinding_invert(blinding, ret, unblind, ctx)) 447 goto err; 448 449 if (padding == RSA_X931_PADDING) { 450 BN_sub(f, rsa->n, ret); 451 if (BN_cmp(ret, f) > 0) 452 res = f; 453 else 454 res = ret; 455 } else 456 res = ret; 457 458 /* put in leading 0 bytes if the number is less than the 459 * length of the modulus */ 460 j = BN_num_bytes(res); 461 i = BN_bn2bin(res, &(to[num - j])); 462 for (k = 0; k < num - i; k++) 463 to[k] = 0; 464 465 r = num; 466 err: 467 if (ctx != NULL) { 468 BN_CTX_end(ctx); 469 BN_CTX_free(ctx); 470 } 471 if (buf != NULL) { 472 explicit_bzero(buf, num); 473 free(buf); 474 } 475 return r; 476 } 477 478 static int 479 RSA_eay_private_decrypt(int flen, const unsigned char *from, unsigned char *to, 480 RSA *rsa, int padding) 481 { 482 BIGNUM *f, *ret; 483 int j, num = 0, r = -1; 484 unsigned char *p; 485 unsigned char *buf = NULL; 486 BN_CTX *ctx = NULL; 487 int local_blinding = 0; 488 /* 489 * Used only if the blinding structure is shared. A non-NULL unblind 490 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store 491 * the unblinding factor outside the blinding structure. 492 */ 493 BIGNUM *unblind = NULL; 494 BN_BLINDING *blinding = NULL; 495 496 if ((ctx = BN_CTX_new()) == NULL) 497 goto err; 498 499 BN_CTX_start(ctx); 500 f = BN_CTX_get(ctx); 501 ret = BN_CTX_get(ctx); 502 num = BN_num_bytes(rsa->n); 503 buf = malloc(num); 504 505 if (!f || !ret || !buf) { 506 RSAerror(ERR_R_MALLOC_FAILURE); 507 goto err; 508 } 509 510 /* This check was for equality but PGP does evil things 511 * and chops off the top '0' bytes */ 512 if (flen > num) { 513 RSAerror(RSA_R_DATA_GREATER_THAN_MOD_LEN); 514 goto err; 515 } 516 517 /* make data into a big number */ 518 if (BN_bin2bn(from, (int)flen, f) == NULL) 519 goto err; 520 521 if (BN_ucmp(f, rsa->n) >= 0) { 522 RSAerror(RSA_R_DATA_TOO_LARGE_FOR_MODULUS); 523 goto err; 524 } 525 526 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) { 527 blinding = rsa_get_blinding(rsa, &local_blinding, ctx); 528 if (blinding == NULL) { 529 RSAerror(ERR_R_INTERNAL_ERROR); 530 goto err; 531 } 532 } 533 534 if (blinding != NULL) { 535 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) { 536 RSAerror(ERR_R_MALLOC_FAILURE); 537 goto err; 538 } 539 if (!rsa_blinding_convert(blinding, f, unblind, ctx)) 540 goto err; 541 } 542 543 /* do the decrypt */ 544 if ((rsa->flags & RSA_FLAG_EXT_PKEY) || 545 (rsa->p != NULL && rsa->q != NULL && rsa->dmp1 != NULL && 546 rsa->dmq1 != NULL && rsa->iqmp != NULL)) { 547 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx)) 548 goto err; 549 } else { 550 BIGNUM d; 551 552 BN_init(&d); 553 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME); 554 555 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC) 556 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, 557 CRYPTO_LOCK_RSA, rsa->n, ctx)) 558 goto err; 559 560 if (!rsa->meth->bn_mod_exp(ret, f, &d, rsa->n, ctx, 561 rsa->_method_mod_n)) { 562 goto err; 563 } 564 } 565 566 if (blinding) 567 if (!rsa_blinding_invert(blinding, ret, unblind, ctx)) 568 goto err; 569 570 p = buf; 571 j = BN_bn2bin(ret, p); /* j is only used with no-padding mode */ 572 573 switch (padding) { 574 case RSA_PKCS1_PADDING: 575 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num); 576 break; 577 #ifndef OPENSSL_NO_SHA 578 case RSA_PKCS1_OAEP_PADDING: 579 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0); 580 break; 581 #endif 582 case RSA_SSLV23_PADDING: 583 r = RSA_padding_check_SSLv23(to, num, buf, j, num); 584 break; 585 case RSA_NO_PADDING: 586 r = RSA_padding_check_none(to, num, buf, j, num); 587 break; 588 default: 589 RSAerror(RSA_R_UNKNOWN_PADDING_TYPE); 590 goto err; 591 } 592 if (r < 0) 593 RSAerror(RSA_R_PADDING_CHECK_FAILED); 594 595 err: 596 if (ctx != NULL) { 597 BN_CTX_end(ctx); 598 BN_CTX_free(ctx); 599 } 600 if (buf != NULL) { 601 explicit_bzero(buf, num); 602 free(buf); 603 } 604 return r; 605 } 606 607 /* signature verification */ 608 static int 609 RSA_eay_public_decrypt(int flen, const unsigned char *from, unsigned char *to, 610 RSA *rsa, int padding) 611 { 612 BIGNUM *f, *ret; 613 int i, num = 0, r = -1; 614 unsigned char *p; 615 unsigned char *buf = NULL; 616 BN_CTX *ctx = NULL; 617 618 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) { 619 RSAerror(RSA_R_MODULUS_TOO_LARGE); 620 return -1; 621 } 622 623 if (BN_ucmp(rsa->n, rsa->e) <= 0) { 624 RSAerror(RSA_R_BAD_E_VALUE); 625 return -1; 626 } 627 628 /* for large moduli, enforce exponent limit */ 629 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) { 630 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) { 631 RSAerror(RSA_R_BAD_E_VALUE); 632 return -1; 633 } 634 } 635 636 if ((ctx = BN_CTX_new()) == NULL) 637 goto err; 638 639 BN_CTX_start(ctx); 640 f = BN_CTX_get(ctx); 641 ret = BN_CTX_get(ctx); 642 num = BN_num_bytes(rsa->n); 643 buf = malloc(num); 644 645 if (!f || !ret || !buf) { 646 RSAerror(ERR_R_MALLOC_FAILURE); 647 goto err; 648 } 649 650 /* This check was for equality but PGP does evil things 651 * and chops off the top '0' bytes */ 652 if (flen > num) { 653 RSAerror(RSA_R_DATA_GREATER_THAN_MOD_LEN); 654 goto err; 655 } 656 657 if (BN_bin2bn(from, flen, f) == NULL) 658 goto err; 659 660 if (BN_ucmp(f, rsa->n) >= 0) { 661 RSAerror(RSA_R_DATA_TOO_LARGE_FOR_MODULUS); 662 goto err; 663 } 664 665 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC) 666 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, 667 CRYPTO_LOCK_RSA, rsa->n, ctx)) 668 goto err; 669 670 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx, 671 rsa->_method_mod_n)) 672 goto err; 673 674 if (padding == RSA_X931_PADDING && (ret->d[0] & 0xf) != 12) 675 if (!BN_sub(ret, rsa->n, ret)) 676 goto err; 677 678 p = buf; 679 i = BN_bn2bin(ret, p); 680 681 switch (padding) { 682 case RSA_PKCS1_PADDING: 683 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num); 684 break; 685 case RSA_X931_PADDING: 686 r = RSA_padding_check_X931(to, num, buf, i, num); 687 break; 688 case RSA_NO_PADDING: 689 r = RSA_padding_check_none(to, num, buf, i, num); 690 break; 691 default: 692 RSAerror(RSA_R_UNKNOWN_PADDING_TYPE); 693 goto err; 694 } 695 if (r < 0) 696 RSAerror(RSA_R_PADDING_CHECK_FAILED); 697 698 err: 699 if (ctx != NULL) { 700 BN_CTX_end(ctx); 701 BN_CTX_free(ctx); 702 } 703 if (buf != NULL) { 704 explicit_bzero(buf, num); 705 free(buf); 706 } 707 return r; 708 } 709 710 static int 711 RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) 712 { 713 BIGNUM *r1, *m1, *vrfy; 714 BIGNUM dmp1, dmq1, c, pr1; 715 int ret = 0; 716 717 BN_CTX_start(ctx); 718 r1 = BN_CTX_get(ctx); 719 m1 = BN_CTX_get(ctx); 720 vrfy = BN_CTX_get(ctx); 721 if (r1 == NULL || m1 == NULL || vrfy == NULL) { 722 RSAerror(ERR_R_MALLOC_FAILURE); 723 goto err; 724 } 725 726 { 727 BIGNUM p, q; 728 729 /* 730 * Make sure BN_mod_inverse in Montgomery intialization uses the 731 * BN_FLG_CONSTTIME flag 732 */ 733 BN_init(&p); 734 BN_init(&q); 735 BN_with_flags(&p, rsa->p, BN_FLG_CONSTTIME); 736 BN_with_flags(&q, rsa->q, BN_FLG_CONSTTIME); 737 738 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) { 739 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_p, 740 CRYPTO_LOCK_RSA, &p, ctx) || 741 !BN_MONT_CTX_set_locked(&rsa->_method_mod_q, 742 CRYPTO_LOCK_RSA, &q, ctx)) { 743 goto err; 744 } 745 } 746 } 747 748 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC) 749 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, 750 CRYPTO_LOCK_RSA, rsa->n, ctx)) 751 goto err; 752 753 /* compute I mod q */ 754 BN_init(&c); 755 BN_with_flags(&c, I, BN_FLG_CONSTTIME); 756 757 if (!BN_mod_ct(r1, &c, rsa->q, ctx)) 758 goto err; 759 760 /* compute r1^dmq1 mod q */ 761 BN_init(&dmq1); 762 BN_with_flags(&dmq1, rsa->dmq1, BN_FLG_CONSTTIME); 763 764 if (!rsa->meth->bn_mod_exp(m1, r1, &dmq1, rsa->q, ctx, 765 rsa->_method_mod_q)) 766 goto err; 767 768 /* compute I mod p */ 769 BN_with_flags(&c, I, BN_FLG_CONSTTIME); 770 771 if (!BN_mod_ct(r1, &c, rsa->p, ctx)) 772 goto err; 773 774 /* compute r1^dmp1 mod p */ 775 BN_init(&dmp1); 776 BN_with_flags(&dmp1, rsa->dmp1, BN_FLG_CONSTTIME); 777 778 if (!rsa->meth->bn_mod_exp(r0, r1, &dmp1, rsa->p, ctx, 779 rsa->_method_mod_p)) 780 goto err; 781 782 if (!BN_sub(r0, r0, m1)) 783 goto err; 784 785 /* 786 * This will help stop the size of r0 increasing, which does 787 * affect the multiply if it optimised for a power of 2 size 788 */ 789 if (BN_is_negative(r0)) 790 if (!BN_add(r0, r0, rsa->p)) 791 goto err; 792 793 if (!BN_mul(r1, r0, rsa->iqmp, ctx)) 794 goto err; 795 796 /* Turn BN_FLG_CONSTTIME flag on before division operation */ 797 BN_init(&pr1); 798 BN_with_flags(&pr1, r1, BN_FLG_CONSTTIME); 799 800 if (!BN_mod_ct(r0, &pr1, rsa->p, ctx)) 801 goto err; 802 803 /* 804 * If p < q it is occasionally possible for the correction of 805 * adding 'p' if r0 is negative above to leave the result still 806 * negative. This can break the private key operations: the following 807 * second correction should *always* correct this rare occurrence. 808 * This will *never* happen with OpenSSL generated keys because 809 * they ensure p > q [steve] 810 */ 811 if (BN_is_negative(r0)) 812 if (!BN_add(r0, r0, rsa->p)) 813 goto err; 814 if (!BN_mul(r1, r0, rsa->q, ctx)) 815 goto err; 816 if (!BN_add(r0, r1, m1)) 817 goto err; 818 819 if (rsa->e && rsa->n) { 820 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx, 821 rsa->_method_mod_n)) 822 goto err; 823 /* 824 * If 'I' was greater than (or equal to) rsa->n, the operation 825 * will be equivalent to using 'I mod n'. However, the result of 826 * the verify will *always* be less than 'n' so we don't check 827 * for absolute equality, just congruency. 828 */ 829 if (!BN_sub(vrfy, vrfy, I)) 830 goto err; 831 if (!BN_mod_ct(vrfy, vrfy, rsa->n, ctx)) 832 goto err; 833 if (BN_is_negative(vrfy)) 834 if (!BN_add(vrfy, vrfy, rsa->n)) 835 goto err; 836 if (!BN_is_zero(vrfy)) { 837 /* 838 * 'I' and 'vrfy' aren't congruent mod n. Don't leak 839 * miscalculated CRT output, just do a raw (slower) 840 * mod_exp and return that instead. 841 */ 842 BIGNUM d; 843 844 BN_init(&d); 845 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME); 846 847 if (!rsa->meth->bn_mod_exp(r0, I, &d, rsa->n, ctx, 848 rsa->_method_mod_n)) { 849 goto err; 850 } 851 } 852 } 853 ret = 1; 854 err: 855 BN_CTX_end(ctx); 856 return ret; 857 } 858 859 static int 860 RSA_eay_init(RSA *rsa) 861 { 862 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE; 863 return 1; 864 } 865 866 static int 867 RSA_eay_finish(RSA *rsa) 868 { 869 BN_MONT_CTX_free(rsa->_method_mod_n); 870 BN_MONT_CTX_free(rsa->_method_mod_p); 871 BN_MONT_CTX_free(rsa->_method_mod_q); 872 873 return 1; 874 } 875