crypto/rsa/rsa_eay.c

   1 /* crypto/rsa/rsa_eay.c */
   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) 1998-2018 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 "cryptlib.h"
 114 #include <openssl/bn.h>
 115 #include <openssl/rsa.h>
 116 #include <openssl/rand.h>
 117 #include "bn_int.h"
 118
 119 #ifndef RSA_NULL
 120
 121 static int RSA_eay_public_encrypt(int flen, const unsigned char *from,
 122                                   unsigned char *to, RSA *rsa, int padding);
 123 static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
 124                                    unsigned char *to, RSA *rsa, int padding);
 125 static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
 126                                   unsigned char *to, RSA *rsa, int padding);
 127 static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
 128                                    unsigned char *to, RSA *rsa, int padding);
 129 static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
 130                            BN_CTX *ctx);
 131 static int RSA_eay_init(RSA *rsa);
 132 static int RSA_eay_finish(RSA *rsa);
 133 static RSA_METHOD rsa_pkcs1_eay_meth = {
 134     "Eric Young's PKCS#1 RSA",
 135     RSA_eay_public_encrypt,
 136     RSA_eay_public_decrypt,     /* signature verification */
 137     RSA_eay_private_encrypt,    /* signing */
 138     RSA_eay_private_decrypt,
 139     RSA_eay_mod_exp,
 140     BN_mod_exp_mont,            /* XXX probably we should not use Montgomery
 141                                  * if e == 3 */
 142     RSA_eay_init,
 143     RSA_eay_finish,
 144     0,                          /* flags */
 145     NULL,
 146     0,                          /* rsa_sign */
 147     0,                          /* rsa_verify */
 148     NULL                        /* rsa_keygen */
 149 };
 150
 151 const RSA_METHOD *RSA_PKCS1_SSLeay(void)
 152 {
 153     return (&rsa_pkcs1_eay_meth);
 154 }
 155
 156 static int RSA_eay_public_encrypt(int flen, const unsigned char *from,
 157                                   unsigned char *to, RSA *rsa, int padding)
 158 {
 159     BIGNUM *f, *ret;
 160     int i, num = 0, r = -1;
 161     unsigned char *buf = NULL;
 162     BN_CTX *ctx = NULL;
 163
 164     if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
 165         RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_MODULUS_TOO_LARGE);
 166         return -1;
 167     }
 168
 169     if (BN_ucmp(rsa->n, rsa->e) <= 0) {
 170         RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
 171         return -1;
 172     }
 173
 174     /* for large moduli, enforce exponent limit */
 175     if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
 176         if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
 177             RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
 178             return -1;
 179         }
 180     }
 181
 182     if ((ctx = BN_CTX_new()) == NULL)
 183         goto err;
 184     BN_CTX_start(ctx);
 185     f = BN_CTX_get(ctx);
 186     ret = BN_CTX_get(ctx);
 187     num = BN_num_bytes(rsa->n);
 188     buf = OPENSSL_malloc(num);
 189     if (!f || !ret || !buf) {
 190         RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, 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         RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, 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         RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT,
 222                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 223         goto err;
 224     }
 225
 226     if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 227         if (!BN_MONT_CTX_set_locked
 228             (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
 229             goto err;
 230
 231     if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
 232                                rsa->_method_mod_n))
 233         goto err;
 234
 235     /*
 236      * BN_bn2binpad puts in leading 0 bytes if the number is less than
 237      * the length of the modulus.
 238      */
 239     r = bn_bn2binpad(ret, to, num);
 240  err:
 241     if (ctx != NULL) {
 242         BN_CTX_end(ctx);
 243         BN_CTX_free(ctx);
 244     }
 245     if (buf != NULL) {
 246         OPENSSL_cleanse(buf, num);
 247         OPENSSL_free(buf);
 248     }
 249     return (r);
 250 }
 251
 252 static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
 253 {
 254     BN_BLINDING *ret;
 255     int got_write_lock = 0;
 256     CRYPTO_THREADID cur;
 257
 258     CRYPTO_r_lock(CRYPTO_LOCK_RSA);
 259
 260     if (rsa->blinding == NULL) {
 261         CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
 262         CRYPTO_w_lock(CRYPTO_LOCK_RSA);
 263         got_write_lock = 1;
 264
 265         if (rsa->blinding == NULL)
 266             rsa->blinding = RSA_setup_blinding(rsa, ctx);
 267     }
 268
 269     ret = rsa->blinding;
 270     if (ret == NULL)
 271         goto err;
 272
 273     CRYPTO_THREADID_current(&cur);
 274     if (!CRYPTO_THREADID_cmp(&cur, BN_BLINDING_thread_id(ret))) {
 275         /* rsa->blinding is ours! */
 276
 277         *local = 1;
 278     } else {
 279         /* resort to rsa->mt_blinding instead */
 280
 281         /*
 282          * instructs rsa_blinding_convert(), rsa_blinding_invert() that the
 283          * BN_BLINDING is shared, meaning that accesses require locks, and
 284          * that the blinding factor must be stored outside the BN_BLINDING
 285          */
 286         *local = 0;
 287
 288         if (rsa->mt_blinding == NULL) {
 289             if (!got_write_lock) {
 290                 CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
 291                 CRYPTO_w_lock(CRYPTO_LOCK_RSA);
 292                 got_write_lock = 1;
 293             }
 294
 295             if (rsa->mt_blinding == NULL)
 296                 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
 297         }
 298         ret = rsa->mt_blinding;
 299     }
 300
 301  err:
 302     if (got_write_lock)
 303         CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
 304     else
 305         CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
 306     return ret;
 307 }
 308
 309 static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
 310                                 BN_CTX *ctx)
 311 {
 312     if (unblind == NULL)
 313         /*
 314          * Local blinding: store the unblinding factor in BN_BLINDING.
 315          */
 316         return BN_BLINDING_convert_ex(f, NULL, b, ctx);
 317     else {
 318         /*
 319          * Shared blinding: store the unblinding factor outside BN_BLINDING.
 320          */
 321         int ret;
 322         CRYPTO_w_lock(CRYPTO_LOCK_RSA_BLINDING);
 323         ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
 324         CRYPTO_w_unlock(CRYPTO_LOCK_RSA_BLINDING);
 325         return ret;
 326     }
 327 }
 328
 329 static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
 330                                BN_CTX *ctx)
 331 {
 332     /*
 333      * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
 334      * will use the unblinding factor stored in BN_BLINDING. If BN_BLINDING
 335      * is shared between threads, unblind must be non-null:
 336      * BN_BLINDING_invert_ex will then use the local unblinding factor, and
 337      * will only read the modulus from BN_BLINDING. In both cases it's safe
 338      * to access the blinding without a lock.
 339      */
 340     return BN_BLINDING_invert_ex(f, unblind, b, ctx);
 341 }
 342
 343 /* signing */
 344 static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
 345                                    unsigned char *to, RSA *rsa, int padding)
 346 {
 347     BIGNUM *f, *ret, *res;
 348     int i, num = 0, r = -1;
 349     unsigned char *buf = NULL;
 350     BN_CTX *ctx = NULL;
 351     int local_blinding = 0;
 352     /*
 353      * Used only if the blinding structure is shared. A non-NULL unblind
 354      * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
 355      * the unblinding factor outside the blinding structure.
 356      */
 357     BIGNUM *unblind = NULL;
 358     BN_BLINDING *blinding = NULL;
 359
 360     if ((ctx = BN_CTX_new()) == NULL)
 361         goto err;
 362     BN_CTX_start(ctx);
 363     f = BN_CTX_get(ctx);
 364     ret = BN_CTX_get(ctx);
 365     num = BN_num_bytes(rsa->n);
 366     buf = OPENSSL_malloc(num);
 367     if (!f || !ret || !buf) {
 368         RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
 369         goto err;
 370     }
 371
 372     switch (padding) {
 373     case RSA_PKCS1_PADDING:
 374         i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
 375         break;
 376     case RSA_X931_PADDING:
 377         i = RSA_padding_add_X931(buf, num, from, flen);
 378         break;
 379     case RSA_NO_PADDING:
 380         i = RSA_padding_add_none(buf, num, from, flen);
 381         break;
 382     case RSA_SSLV23_PADDING:
 383     default:
 384         RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 385         goto err;
 386     }
 387     if (i <= 0)
 388         goto err;
 389
 390     if (BN_bin2bn(buf, num, f) == NULL)
 391         goto err;
 392
 393     if (BN_ucmp(f, rsa->n) >= 0) {
 394         /* usually the padding functions would catch this */
 395         RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,
 396                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 397         goto err;
 398     }
 399
 400     if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
 401         blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
 402         if (blinding == NULL) {
 403             RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, ERR_R_INTERNAL_ERROR);
 404             goto err;
 405         }
 406     }
 407
 408     if (blinding != NULL) {
 409         if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
 410             RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
 411             goto err;
 412         }
 413         if (!rsa_blinding_convert(blinding, f, unblind, ctx))
 414             goto err;
 415     }
 416
 417     if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
 418         ((rsa->p != NULL) &&
 419          (rsa->q != NULL) &&
 420          (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
 421         if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
 422             goto err;
 423     } else {
 424         BIGNUM local_d;
 425         BIGNUM *d = NULL;
 426
 427         if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 428             BN_init(&local_d);
 429             d = &local_d;
 430             BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
 431         } else
 432             d = rsa->d;
 433
 434         if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 435             if (!BN_MONT_CTX_set_locked
 436                 (&rsa->_method_mod_n, 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     if (blinding)
 445         if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
 446             goto err;
 447
 448     if (padding == RSA_X931_PADDING) {
 449         BN_sub(f, rsa->n, ret);
 450         if (BN_cmp(ret, f) > 0)
 451             res = f;
 452         else
 453             res = ret;
 454     } else
 455         res = ret;
 456
 457     /*
 458      * BN_bn2binpad puts in leading 0 bytes if the number is less than
 459      * the length of the modulus.
 460      */
 461     r = bn_bn2binpad(res, to, num);
 462  err:
 463     if (ctx != NULL) {
 464         BN_CTX_end(ctx);
 465         BN_CTX_free(ctx);
 466     }
 467     if (buf != NULL) {
 468         OPENSSL_cleanse(buf, num);
 469         OPENSSL_free(buf);
 470     }
 471     return (r);
 472 }
 473
 474 static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
 475                                    unsigned char *to, RSA *rsa, int padding)
 476 {
 477     BIGNUM *f, *ret;
 478     int j, num = 0, r = -1;
 479     unsigned char *buf = NULL;
 480     BN_CTX *ctx = NULL;
 481     int local_blinding = 0;
 482     /*
 483      * Used only if the blinding structure is shared. A non-NULL unblind
 484      * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
 485      * the unblinding factor outside the blinding structure.
 486      */
 487     BIGNUM *unblind = NULL;
 488     BN_BLINDING *blinding = NULL;
 489
 490     if ((ctx = BN_CTX_new()) == NULL)
 491         goto err;
 492     BN_CTX_start(ctx);
 493     f = BN_CTX_get(ctx);
 494     ret = BN_CTX_get(ctx);
 495     num = BN_num_bytes(rsa->n);
 496     buf = OPENSSL_malloc(num);
 497     if (!f || !ret || !buf) {
 498         RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
 499         goto err;
 500     }
 501
 502     /*
 503      * This check was for equality but PGP does evil things and chops off the
 504      * top '0' bytes
 505      */
 506     if (flen > num) {
 507         RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,
 508                RSA_R_DATA_GREATER_THAN_MOD_LEN);
 509         goto err;
 510     }
 511
 512     /* make data into a big number */
 513     if (BN_bin2bn(from, (int)flen, f) == NULL)
 514         goto err;
 515
 516     if (BN_ucmp(f, rsa->n) >= 0) {
 517         RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,
 518                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 519         goto err;
 520     }
 521
 522     if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
 523         blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
 524         if (blinding == NULL) {
 525             RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
 526             goto err;
 527         }
 528     }
 529
 530     if (blinding != NULL) {
 531         if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
 532             RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
 533             goto err;
 534         }
 535         if (!rsa_blinding_convert(blinding, f, unblind, ctx))
 536             goto err;
 537     }
 538
 539     /* do the decrypt */
 540     if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
 541         ((rsa->p != NULL) &&
 542          (rsa->q != NULL) &&
 543          (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
 544         if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
 545             goto err;
 546     } else {
 547         BIGNUM local_d;
 548         BIGNUM *d = NULL;
 549
 550         if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 551             d = &local_d;
 552             BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
 553         } else
 554             d = rsa->d;
 555
 556         if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 557             if (!BN_MONT_CTX_set_locked
 558                 (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
 559                 goto err;
 560         if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
 561                                    rsa->_method_mod_n))
 562             goto err;
 563     }
 564
 565     if (blinding)
 566         if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
 567             goto err;
 568
 569     j = bn_bn2binpad(ret, buf, num);
 570
 571     switch (padding) {
 572     case RSA_PKCS1_PADDING:
 573         r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
 574         break;
 575 # ifndef OPENSSL_NO_SHA
 576     case RSA_PKCS1_OAEP_PADDING:
 577         r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
 578         break;
 579 # endif
 580     case RSA_SSLV23_PADDING:
 581         r = RSA_padding_check_SSLv23(to, num, buf, j, num);
 582         break;
 583     case RSA_NO_PADDING:
 584         memcpy(to, buf, (r = j));
 585         break;
 586     default:
 587         RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 588         goto err;
 589     }
 590     if (r < 0)
 591         RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
 592
 593  err:
 594     if (ctx != NULL) {
 595         BN_CTX_end(ctx);
 596         BN_CTX_free(ctx);
 597     }
 598     if (buf != NULL) {
 599         OPENSSL_cleanse(buf, num);
 600         OPENSSL_free(buf);
 601     }
 602     return (r);
 603 }
 604
 605 /* signature verification */
 606 static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
 607                                   unsigned char *to, RSA *rsa, int padding)
 608 {
 609     BIGNUM *f, *ret;
 610     int i, num = 0, r = -1;
 611     unsigned char *buf = NULL;
 612     BN_CTX *ctx = NULL;
 613
 614     if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
 615         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
 616         return -1;
 617     }
 618
 619     if (BN_ucmp(rsa->n, rsa->e) <= 0) {
 620         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
 621         return -1;
 622     }
 623
 624     /* for large moduli, enforce exponent limit */
 625     if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
 626         if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
 627             RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
 628             return -1;
 629         }
 630     }
 631
 632     if ((ctx = BN_CTX_new()) == NULL)
 633         goto err;
 634     BN_CTX_start(ctx);
 635     f = BN_CTX_get(ctx);
 636     ret = BN_CTX_get(ctx);
 637     num = BN_num_bytes(rsa->n);
 638     buf = OPENSSL_malloc(num);
 639     if (!f || !ret || !buf) {
 640         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
 641         goto err;
 642     }
 643
 644     /*
 645      * This check was for equality but PGP does evil things and chops off the
 646      * top '0' bytes
 647      */
 648     if (flen > num) {
 649         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_DATA_GREATER_THAN_MOD_LEN);
 650         goto err;
 651     }
 652
 653     if (BN_bin2bn(from, flen, f) == NULL)
 654         goto err;
 655
 656     if (BN_ucmp(f, rsa->n) >= 0) {
 657         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,
 658                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 659         goto err;
 660     }
 661
 662     if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 663         if (!BN_MONT_CTX_set_locked
 664             (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
 665             goto err;
 666
 667     if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
 668                                rsa->_method_mod_n))
 669         goto err;
 670
 671     if ((padding == RSA_X931_PADDING) && ((ret->d[0] & 0xf) != 12))
 672         if (!BN_sub(ret, rsa->n, ret))
 673             goto err;
 674
 675     i = bn_bn2binpad(ret, buf, num);
 676
 677     switch (padding) {
 678     case RSA_PKCS1_PADDING:
 679         r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
 680         break;
 681     case RSA_X931_PADDING:
 682         r = RSA_padding_check_X931(to, num, buf, i, num);
 683         break;
 684     case RSA_NO_PADDING:
 685         memcpy(to, buf, (r = i));
 686         break;
 687     default:
 688         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 689         goto err;
 690     }
 691     if (r < 0)
 692         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
 693
 694  err:
 695     if (ctx != NULL) {
 696         BN_CTX_end(ctx);
 697         BN_CTX_free(ctx);
 698     }
 699     if (buf != NULL) {
 700         OPENSSL_cleanse(buf, num);
 701         OPENSSL_free(buf);
 702     }
 703     return (r);
 704 }
 705
 706 static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
 707 {
 708     BIGNUM *r1, *m1, *vrfy;
 709     BIGNUM local_dmp1, local_dmq1, local_c, local_r1;
 710     BIGNUM *dmp1, *dmq1, *c, *pr1;
 711     int ret = 0;
 712
 713     BN_CTX_start(ctx);
 714     r1 = BN_CTX_get(ctx);
 715     m1 = BN_CTX_get(ctx);
 716     vrfy = BN_CTX_get(ctx);
 717
 718     {
 719         BIGNUM local_p, local_q;
 720         BIGNUM *p = NULL, *q = NULL;
 721
 722         /*
 723          * Make sure BN_mod_inverse in Montgomery intialization uses the
 724          * BN_FLG_CONSTTIME flag (unless RSA_FLAG_NO_CONSTTIME is set)
 725          */
 726         if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 727             BN_init(&local_p);
 728             p = &local_p;
 729             BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
 730
 731             BN_init(&local_q);
 732             q = &local_q;
 733             BN_with_flags(q, rsa->q, BN_FLG_CONSTTIME);
 734         } else {
 735             p = rsa->p;
 736             q = rsa->q;
 737         }
 738
 739         if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
 740             if (!BN_MONT_CTX_set_locked
 741                 (&rsa->_method_mod_p, CRYPTO_LOCK_RSA, p, ctx))
 742                 goto err;
 743             if (!BN_MONT_CTX_set_locked
 744                 (&rsa->_method_mod_q, CRYPTO_LOCK_RSA, q, ctx))
 745                 goto err;
 746         }
 747     }
 748
 749     if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 750         if (!BN_MONT_CTX_set_locked
 751             (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
 752             goto err;
 753
 754     /* compute I mod q */
 755     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 756         c = &local_c;
 757         BN_with_flags(c, I, BN_FLG_CONSTTIME);
 758         if (!BN_mod(r1, c, rsa->q, ctx))
 759             goto err;
 760     } else {
 761         if (!BN_mod(r1, I, rsa->q, ctx))
 762             goto err;
 763     }
 764
 765     /* compute r1^dmq1 mod q */
 766     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 767         dmq1 = &local_dmq1;
 768         BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
 769     } else
 770         dmq1 = rsa->dmq1;
 771     if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx, rsa->_method_mod_q))
 772         goto err;
 773
 774     /* compute I mod p */
 775     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 776         c = &local_c;
 777         BN_with_flags(c, I, BN_FLG_CONSTTIME);
 778         if (!BN_mod(r1, c, rsa->p, ctx))
 779             goto err;
 780     } else {
 781         if (!BN_mod(r1, I, rsa->p, ctx))
 782             goto err;
 783     }
 784
 785     /* compute r1^dmp1 mod p */
 786     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 787         dmp1 = &local_dmp1;
 788         BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
 789     } else
 790         dmp1 = rsa->dmp1;
 791     if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx, rsa->_method_mod_p))
 792         goto err;
 793
 794     if (!BN_sub(r0, r0, m1))
 795         goto err;
 796     /*
 797      * This will help stop the size of r0 increasing, which does affect the
 798      * multiply if it optimised for a power of 2 size
 799      */
 800     if (BN_is_negative(r0))
 801         if (!BN_add(r0, r0, rsa->p))
 802             goto err;
 803
 804     if (!BN_mul(r1, r0, rsa->iqmp, ctx))
 805         goto err;
 806
 807     /* Turn BN_FLG_CONSTTIME flag on before division operation */
 808     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 809         pr1 = &local_r1;
 810         BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
 811     } else
 812         pr1 = r1;
 813     if (!BN_mod(r0, pr1, rsa->p, ctx))
 814         goto err;
 815
 816     /*
 817      * If p < q it is occasionally possible for the correction of adding 'p'
 818      * if r0 is negative above to leave the result still negative. This can
 819      * break the private key operations: the following second correction
 820      * should *always* correct this rare occurrence. This will *never* happen
 821      * with OpenSSL generated keys because they ensure p > q [steve]
 822      */
 823     if (BN_is_negative(r0))
 824         if (!BN_add(r0, r0, rsa->p))
 825             goto err;
 826     if (!BN_mul(r1, r0, rsa->q, ctx))
 827         goto err;
 828     if (!BN_add(r0, r1, m1))
 829         goto err;
 830
 831     if (rsa->e && rsa->n) {
 832         if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
 833                                    rsa->_method_mod_n))
 834             goto err;
 835         /*
 836          * If 'I' was greater than (or equal to) rsa->n, the operation will
 837          * be equivalent to using 'I mod n'. However, the result of the
 838          * verify will *always* be less than 'n' so we don't check for
 839          * absolute equality, just congruency.
 840          */
 841         if (!BN_sub(vrfy, vrfy, I))
 842             goto err;
 843         if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
 844             goto err;
 845         if (BN_is_negative(vrfy))
 846             if (!BN_add(vrfy, vrfy, rsa->n))
 847                 goto err;
 848         if (!BN_is_zero(vrfy)) {
 849             /*
 850              * 'I' and 'vrfy' aren't congruent mod n. Don't leak
 851              * miscalculated CRT output, just do a raw (slower) mod_exp and
 852              * return that instead.
 853              */
 854
 855             BIGNUM local_d;
 856             BIGNUM *d = NULL;
 857
 858             if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 859                 d = &local_d;
 860                 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
 861             } else
 862                 d = rsa->d;
 863             if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
 864                                        rsa->_method_mod_n))
 865                 goto err;
 866         }
 867     }
 868     ret = 1;
 869  err:
 870     BN_CTX_end(ctx);
 871     return (ret);
 872 }
 873
 874 static int RSA_eay_init(RSA *rsa)
 875 {
 876     rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
 877     return (1);
 878 }
 879
 880 static int RSA_eay_finish(RSA *rsa)
 881 {
 882     if (rsa->_method_mod_n != NULL)
 883         BN_MONT_CTX_free(rsa->_method_mod_n);
 884     if (rsa->_method_mod_p != NULL)
 885         BN_MONT_CTX_free(rsa->_method_mod_p);
 886     if (rsa->_method_mod_q != NULL)
 887         BN_MONT_CTX_free(rsa->_method_mod_q);
 888     return (1);
 889 }
 890
 891 #endif