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) 1998-2006 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 "cryptlib.h"
 114 #include <openssl/bn.h>
 115 #include <openssl/rsa.h>
 116 #include <openssl/rand.h>
 117
 118 #ifndef RSA_NULL
 119
 120 static int RSA_eay_public_encrypt(int flen, const unsigned char *from,
 121                                   unsigned char *to, RSA *rsa, int padding);
 122 static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
 123                                    unsigned char *to, RSA *rsa, int padding);
 124 static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
 125                                   unsigned char *to, RSA *rsa, int padding);
 126 static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
 127                                    unsigned char *to, RSA *rsa, int padding);
 128 static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
 129                            BN_CTX *ctx);
 130 static int RSA_eay_init(RSA *rsa);
 131 static int RSA_eay_finish(RSA *rsa);
 132 static RSA_METHOD rsa_pkcs1_eay_meth = {
 133     "Eric Young's PKCS#1 RSA",
 134     RSA_eay_public_encrypt,
 135     RSA_eay_public_decrypt,     /* signature verification */
 136     RSA_eay_private_encrypt,    /* signing */
 137     RSA_eay_private_decrypt,
 138     RSA_eay_mod_exp,
 139     BN_mod_exp_mont,            /* XXX probably we should not use Montgomery
 140                                  * if e == 3 */
 141     RSA_eay_init,
 142     RSA_eay_finish,
 143     0,                          /* flags */
 144     NULL,
 145     0,                          /* rsa_sign */
 146     0,                          /* rsa_verify */
 147     NULL                        /* rsa_keygen */
 148 };
 149
 150 const RSA_METHOD *RSA_PKCS1_SSLeay(void)
 151 {
 152     return (&rsa_pkcs1_eay_meth);
 153 }
 154
 155 static int RSA_eay_public_encrypt(int flen, const unsigned char *from,
 156                                   unsigned char *to, RSA *rsa, int padding)
 157 {
 158     BIGNUM *f, *ret;
 159     int i, j, k, num = 0, r = -1;
 160     unsigned char *buf = NULL;
 161     BN_CTX *ctx = NULL;
 162
 163     if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
 164         RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_MODULUS_TOO_LARGE);
 165         return -1;
 166     }
 167
 168     if (BN_ucmp(rsa->n, rsa->e) <= 0) {
 169         RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
 170         return -1;
 171     }
 172
 173     /* for large moduli, enforce exponent limit */
 174     if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
 175         if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
 176             RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
 177             return -1;
 178         }
 179     }
 180
 181     if ((ctx = BN_CTX_new()) == NULL)
 182         goto err;
 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 = OPENSSL_malloc(num);
 188     if (!f || !ret || !buf) {
 189         RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, ERR_R_MALLOC_FAILURE);
 190         goto err;
 191     }
 192
 193     switch (padding) {
 194     case RSA_PKCS1_PADDING:
 195         i = RSA_padding_add_PKCS1_type_2(buf, num, from, flen);
 196         break;
 197 # ifndef OPENSSL_NO_SHA
 198     case RSA_PKCS1_OAEP_PADDING:
 199         i = RSA_padding_add_PKCS1_OAEP(buf, num, from, flen, NULL, 0);
 200         break;
 201 # endif
 202     case RSA_SSLV23_PADDING:
 203         i = RSA_padding_add_SSLv23(buf, num, from, flen);
 204         break;
 205     case RSA_NO_PADDING:
 206         i = RSA_padding_add_none(buf, num, from, flen);
 207         break;
 208     default:
 209         RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 210         goto err;
 211     }
 212     if (i <= 0)
 213         goto err;
 214
 215     if (BN_bin2bn(buf, num, f) == NULL)
 216         goto err;
 217
 218     if (BN_ucmp(f, rsa->n) >= 0) {
 219         /* usually the padding functions would catch this */
 220         RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT,
 221                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
 227             (&rsa->_method_mod_n, 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     /*
 235      * put in leading 0 bytes if the number is less than the length of the
 236      * modulus
 237      */
 238     j = BN_num_bytes(ret);
 239     i = BN_bn2bin(ret, &(to[num - j]));
 240     for (k = 0; k < (num - i); k++)
 241         to[k] = 0;
 242
 243     r = num;
 244  err:
 245     if (ctx != NULL) {
 246         BN_CTX_end(ctx);
 247         BN_CTX_free(ctx);
 248     }
 249     if (buf != NULL) {
 250         OPENSSL_cleanse(buf, num);
 251         OPENSSL_free(buf);
 252     }
 253     return (r);
 254 }
 255
 256 static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
 257 {
 258     BN_BLINDING *ret;
 259     int got_write_lock = 0;
 260     CRYPTO_THREADID cur;
 261
 262     CRYPTO_r_lock(CRYPTO_LOCK_RSA);
 263
 264     if (rsa->blinding == NULL) {
 265         CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
 266         CRYPTO_w_lock(CRYPTO_LOCK_RSA);
 267         got_write_lock = 1;
 268
 269         if (rsa->blinding == NULL)
 270             rsa->blinding = RSA_setup_blinding(rsa, ctx);
 271     }
 272
 273     ret = rsa->blinding;
 274     if (ret == NULL)
 275         goto err;
 276
 277     CRYPTO_THREADID_current(&cur);
 278     if (!CRYPTO_THREADID_cmp(&cur, BN_BLINDING_thread_id(ret))) {
 279         /* rsa->blinding is ours! */
 280
 281         *local = 1;
 282     } else {
 283         /* resort to rsa->mt_blinding instead */
 284
 285         /*
 286          * instructs rsa_blinding_convert(), rsa_blinding_invert() that the
 287          * BN_BLINDING is shared, meaning that accesses require locks, and
 288          * that the blinding factor must be stored outside the BN_BLINDING
 289          */
 290         *local = 0;
 291
 292         if (rsa->mt_blinding == NULL) {
 293             if (!got_write_lock) {
 294                 CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
 295                 CRYPTO_w_lock(CRYPTO_LOCK_RSA);
 296                 got_write_lock = 1;
 297             }
 298
 299             if (rsa->mt_blinding == NULL)
 300                 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
 301         }
 302         ret = rsa->mt_blinding;
 303     }
 304
 305  err:
 306     if (got_write_lock)
 307         CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
 308     else
 309         CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
 310     return ret;
 311 }
 312
 313 static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
 314                                 BN_CTX *ctx)
 315 {
 316     if (unblind == NULL)
 317         /*
 318          * Local blinding: store the unblinding factor in BN_BLINDING.
 319          */
 320         return BN_BLINDING_convert_ex(f, NULL, b, ctx);
 321     else {
 322         /*
 323          * Shared blinding: store the unblinding factor 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 rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
 334                                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. If BN_BLINDING
 339      * is shared between threads, unblind must be non-null:
 340      * BN_BLINDING_invert_ex will then use the local unblinding factor, and
 341      * will only read the modulus from BN_BLINDING. In both cases it's safe
 342      * 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 RSA_eay_private_encrypt(int flen, const unsigned char *from,
 349                                    unsigned char *to, RSA *rsa, int padding)
 350 {
 351     BIGNUM *f, *ret, *res;
 352     int i, j, k, num = 0, r = -1;
 353     unsigned char *buf = NULL;
 354     BN_CTX *ctx = NULL;
 355     int local_blinding = 0;
 356     /*
 357      * Used only if the blinding structure is shared. A non-NULL unblind
 358      * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
 359      * the unblinding factor outside the blinding structure.
 360      */
 361     BIGNUM *unblind = NULL;
 362     BN_BLINDING *blinding = NULL;
 363
 364     if ((ctx = BN_CTX_new()) == NULL)
 365         goto err;
 366     BN_CTX_start(ctx);
 367     f = BN_CTX_get(ctx);
 368     ret = BN_CTX_get(ctx);
 369     num = BN_num_bytes(rsa->n);
 370     buf = OPENSSL_malloc(num);
 371     if (!f || !ret || !buf) {
 372         RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
 373         goto err;
 374     }
 375
 376     switch (padding) {
 377     case RSA_PKCS1_PADDING:
 378         i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
 379         break;
 380     case RSA_X931_PADDING:
 381         i = RSA_padding_add_X931(buf, num, from, flen);
 382         break;
 383     case RSA_NO_PADDING:
 384         i = RSA_padding_add_none(buf, num, from, flen);
 385         break;
 386     case RSA_SSLV23_PADDING:
 387     default:
 388         RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 389         goto err;
 390     }
 391     if (i <= 0)
 392         goto err;
 393
 394     if (BN_bin2bn(buf, num, f) == NULL)
 395         goto err;
 396
 397     if (BN_ucmp(f, rsa->n) >= 0) {
 398         /* usually the padding functions would catch this */
 399         RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,
 400                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 401         goto err;
 402     }
 403
 404     if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
 405         blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
 406         if (blinding == NULL) {
 407             RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, ERR_R_INTERNAL_ERROR);
 408             goto err;
 409         }
 410     }
 411
 412     if (blinding != NULL) {
 413         if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
 414             RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
 415             goto err;
 416         }
 417         if (!rsa_blinding_convert(blinding, f, unblind, ctx))
 418             goto err;
 419     }
 420
 421     if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
 422         ((rsa->p != NULL) &&
 423          (rsa->q != NULL) &&
 424          (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
 425         if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
 426             goto err;
 427     } else {
 428         BIGNUM local_d;
 429         BIGNUM *d = NULL;
 430
 431         if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 432             BN_init(&local_d);
 433             d = &local_d;
 434             BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
 435         } else
 436             d = rsa->d;
 437
 438         if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 439             if (!BN_MONT_CTX_set_locked
 440                 (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
 441                 goto err;
 442
 443         if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
 444                                    rsa->_method_mod_n))
 445             goto err;
 446     }
 447
 448     if (blinding)
 449         if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
 450             goto err;
 451
 452     if (padding == RSA_X931_PADDING) {
 453         BN_sub(f, rsa->n, ret);
 454         if (BN_cmp(ret, f) > 0)
 455             res = f;
 456         else
 457             res = ret;
 458     } else
 459         res = ret;
 460
 461     /*
 462      * put in leading 0 bytes if the number is less than the length of the
 463      * modulus
 464      */
 465     j = BN_num_bytes(res);
 466     i = BN_bn2bin(res, &(to[num - j]));
 467     for (k = 0; k < (num - i); k++)
 468         to[k] = 0;
 469
 470     r = num;
 471  err:
 472     if (ctx != NULL) {
 473         BN_CTX_end(ctx);
 474         BN_CTX_free(ctx);
 475     }
 476     if (buf != NULL) {
 477         OPENSSL_cleanse(buf, num);
 478         OPENSSL_free(buf);
 479     }
 480     return (r);
 481 }
 482
 483 static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
 484                                    unsigned char *to, RSA *rsa, int padding)
 485 {
 486     BIGNUM *f, *ret;
 487     int j, num = 0, r = -1;
 488     unsigned char *p;
 489     unsigned char *buf = NULL;
 490     BN_CTX *ctx = NULL;
 491     int local_blinding = 0;
 492     /*
 493      * Used only if the blinding structure is shared. A non-NULL unblind
 494      * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
 495      * the unblinding factor outside the blinding structure.
 496      */
 497     BIGNUM *unblind = NULL;
 498     BN_BLINDING *blinding = NULL;
 499
 500     if ((ctx = BN_CTX_new()) == NULL)
 501         goto err;
 502     BN_CTX_start(ctx);
 503     f = BN_CTX_get(ctx);
 504     ret = BN_CTX_get(ctx);
 505     num = BN_num_bytes(rsa->n);
 506     buf = OPENSSL_malloc(num);
 507     if (!f || !ret || !buf) {
 508         RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
 509         goto err;
 510     }
 511
 512     /*
 513      * This check was for equality but PGP does evil things and chops off the
 514      * top '0' bytes
 515      */
 516     if (flen > num) {
 517         RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,
 518                RSA_R_DATA_GREATER_THAN_MOD_LEN);
 519         goto err;
 520     }
 521
 522     /* make data into a big number */
 523     if (BN_bin2bn(from, (int)flen, f) == NULL)
 524         goto err;
 525
 526     if (BN_ucmp(f, rsa->n) >= 0) {
 527         RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,
 528                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 529         goto err;
 530     }
 531
 532     if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
 533         blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
 534         if (blinding == NULL) {
 535             RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
 536             goto err;
 537         }
 538     }
 539
 540     if (blinding != NULL) {
 541         if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
 542             RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
 543             goto err;
 544         }
 545         if (!rsa_blinding_convert(blinding, f, unblind, ctx))
 546             goto err;
 547     }
 548
 549     /* do the decrypt */
 550     if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
 551         ((rsa->p != NULL) &&
 552          (rsa->q != NULL) &&
 553          (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
 554         if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
 555             goto err;
 556     } else {
 557         BIGNUM local_d;
 558         BIGNUM *d = NULL;
 559
 560         if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 561             d = &local_d;
 562             BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
 563         } else
 564             d = rsa->d;
 565
 566         if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 567             if (!BN_MONT_CTX_set_locked
 568                 (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
 569                 goto err;
 570         if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
 571                                    rsa->_method_mod_n))
 572             goto err;
 573     }
 574
 575     if (blinding)
 576         if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
 577             goto err;
 578
 579     p = buf;
 580     j = BN_bn2bin(ret, p);      /* j is only used with no-padding mode */
 581
 582     switch (padding) {
 583     case RSA_PKCS1_PADDING:
 584         r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
 585         break;
 586 # ifndef OPENSSL_NO_SHA
 587     case RSA_PKCS1_OAEP_PADDING:
 588         r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
 589         break;
 590 # endif
 591     case RSA_SSLV23_PADDING:
 592         r = RSA_padding_check_SSLv23(to, num, buf, j, num);
 593         break;
 594     case RSA_NO_PADDING:
 595         r = RSA_padding_check_none(to, num, buf, j, num);
 596         break;
 597     default:
 598         RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 599         goto err;
 600     }
 601     if (r < 0)
 602         RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
 603
 604  err:
 605     if (ctx != NULL) {
 606         BN_CTX_end(ctx);
 607         BN_CTX_free(ctx);
 608     }
 609     if (buf != NULL) {
 610         OPENSSL_cleanse(buf, num);
 611         OPENSSL_free(buf);
 612     }
 613     return (r);
 614 }
 615
 616 /* signature verification */
 617 static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
 618                                   unsigned char *to, RSA *rsa, int padding)
 619 {
 620     BIGNUM *f, *ret;
 621     int i, num = 0, r = -1;
 622     unsigned char *p;
 623     unsigned char *buf = NULL;
 624     BN_CTX *ctx = NULL;
 625
 626     if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
 627         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
 628         return -1;
 629     }
 630
 631     if (BN_ucmp(rsa->n, rsa->e) <= 0) {
 632         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
 633         return -1;
 634     }
 635
 636     /* for large moduli, enforce exponent limit */
 637     if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
 638         if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
 639             RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
 640             return -1;
 641         }
 642     }
 643
 644     if ((ctx = BN_CTX_new()) == NULL)
 645         goto err;
 646     BN_CTX_start(ctx);
 647     f = BN_CTX_get(ctx);
 648     ret = BN_CTX_get(ctx);
 649     num = BN_num_bytes(rsa->n);
 650     buf = OPENSSL_malloc(num);
 651     if (!f || !ret || !buf) {
 652         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
 653         goto err;
 654     }
 655
 656     /*
 657      * This check was for equality but PGP does evil things and chops off the
 658      * top '0' bytes
 659      */
 660     if (flen > num) {
 661         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_DATA_GREATER_THAN_MOD_LEN);
 662         goto err;
 663     }
 664
 665     if (BN_bin2bn(from, flen, f) == NULL)
 666         goto err;
 667
 668     if (BN_ucmp(f, rsa->n) >= 0) {
 669         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,
 670                RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
 671         goto err;
 672     }
 673
 674     if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 675         if (!BN_MONT_CTX_set_locked
 676             (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
 677             goto err;
 678
 679     if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
 680                                rsa->_method_mod_n))
 681         goto err;
 682
 683     if ((padding == RSA_X931_PADDING) && ((ret->d[0] & 0xf) != 12))
 684         if (!BN_sub(ret, rsa->n, ret))
 685             goto err;
 686
 687     p = buf;
 688     i = BN_bn2bin(ret, p);
 689
 690     switch (padding) {
 691     case RSA_PKCS1_PADDING:
 692         r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
 693         break;
 694     case RSA_X931_PADDING:
 695         r = RSA_padding_check_X931(to, num, buf, i, num);
 696         break;
 697     case RSA_NO_PADDING:
 698         r = RSA_padding_check_none(to, num, buf, i, num);
 699         break;
 700     default:
 701         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
 702         goto err;
 703     }
 704     if (r < 0)
 705         RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
 706
 707  err:
 708     if (ctx != NULL) {
 709         BN_CTX_end(ctx);
 710         BN_CTX_free(ctx);
 711     }
 712     if (buf != NULL) {
 713         OPENSSL_cleanse(buf, num);
 714         OPENSSL_free(buf);
 715     }
 716     return (r);
 717 }
 718
 719 static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
 720 {
 721     BIGNUM *r1, *m1, *vrfy;
 722     BIGNUM local_dmp1, local_dmq1, local_c, local_r1;
 723     BIGNUM *dmp1, *dmq1, *c, *pr1;
 724     int ret = 0;
 725
 726     BN_CTX_start(ctx);
 727     r1 = BN_CTX_get(ctx);
 728     m1 = BN_CTX_get(ctx);
 729     vrfy = BN_CTX_get(ctx);
 730
 731     {
 732         BIGNUM local_p, local_q;
 733         BIGNUM *p = NULL, *q = NULL;
 734
 735         /*
 736          * Make sure BN_mod_inverse in Montgomery intialization uses the
 737          * BN_FLG_CONSTTIME flag (unless RSA_FLAG_NO_CONSTTIME is set)
 738          */
 739         if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 740             BN_init(&local_p);
 741             p = &local_p;
 742             BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
 743
 744             BN_init(&local_q);
 745             q = &local_q;
 746             BN_with_flags(q, rsa->q, BN_FLG_CONSTTIME);
 747         } else {
 748             p = rsa->p;
 749             q = rsa->q;
 750         }
 751
 752         if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
 753             if (!BN_MONT_CTX_set_locked
 754                 (&rsa->_method_mod_p, CRYPTO_LOCK_RSA, p, ctx))
 755                 goto err;
 756             if (!BN_MONT_CTX_set_locked
 757                 (&rsa->_method_mod_q, CRYPTO_LOCK_RSA, q, ctx))
 758                 goto err;
 759         }
 760     }
 761
 762     if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
 763         if (!BN_MONT_CTX_set_locked
 764             (&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
 765             goto err;
 766
 767     /* compute I mod q */
 768     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 769         c = &local_c;
 770         BN_with_flags(c, I, BN_FLG_CONSTTIME);
 771         if (!BN_mod(r1, c, rsa->q, ctx))
 772             goto err;
 773     } else {
 774         if (!BN_mod(r1, I, rsa->q, ctx))
 775             goto err;
 776     }
 777
 778     /* compute r1^dmq1 mod q */
 779     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 780         dmq1 = &local_dmq1;
 781         BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
 782     } else
 783         dmq1 = rsa->dmq1;
 784     if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx, rsa->_method_mod_q))
 785         goto err;
 786
 787     /* compute I mod p */
 788     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 789         c = &local_c;
 790         BN_with_flags(c, I, BN_FLG_CONSTTIME);
 791         if (!BN_mod(r1, c, rsa->p, ctx))
 792             goto err;
 793     } else {
 794         if (!BN_mod(r1, I, rsa->p, ctx))
 795             goto err;
 796     }
 797
 798     /* compute r1^dmp1 mod p */
 799     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 800         dmp1 = &local_dmp1;
 801         BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
 802     } else
 803         dmp1 = rsa->dmp1;
 804     if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx, rsa->_method_mod_p))
 805         goto err;
 806
 807     if (!BN_sub(r0, r0, m1))
 808         goto err;
 809     /*
 810      * This will help stop the size of r0 increasing, which does affect the
 811      * multiply if it optimised for a power of 2 size
 812      */
 813     if (BN_is_negative(r0))
 814         if (!BN_add(r0, r0, rsa->p))
 815             goto err;
 816
 817     if (!BN_mul(r1, r0, rsa->iqmp, ctx))
 818         goto err;
 819
 820     /* Turn BN_FLG_CONSTTIME flag on before division operation */
 821     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 822         pr1 = &local_r1;
 823         BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
 824     } else
 825         pr1 = r1;
 826     if (!BN_mod(r0, pr1, rsa->p, ctx))
 827         goto err;
 828
 829     /*
 830      * If p < q it is occasionally possible for the correction of adding 'p'
 831      * if r0 is negative above to leave the result still negative. This can
 832      * break the private key operations: the following second correction
 833      * should *always* correct this rare occurrence. This will *never* happen
 834      * with OpenSSL generated keys because they ensure p > q [steve]
 835      */
 836     if (BN_is_negative(r0))
 837         if (!BN_add(r0, r0, rsa->p))
 838             goto err;
 839     if (!BN_mul(r1, r0, rsa->q, ctx))
 840         goto err;
 841     if (!BN_add(r0, r1, m1))
 842         goto err;
 843
 844     if (rsa->e && rsa->n) {
 845         if (!rsa->
 846             meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
 847                              rsa->_method_mod_n))
 848             goto err;
 849         /*
 850          * If 'I' was greater than (or equal to) rsa->n, the operation will
 851          * be equivalent to using 'I mod n'. However, the result of the
 852          * verify will *always* be less than 'n' so we don't check for
 853          * absolute equality, just congruency.
 854          */
 855         if (!BN_sub(vrfy, vrfy, I))
 856             goto err;
 857         if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
 858             goto err;
 859         if (BN_is_negative(vrfy))
 860             if (!BN_add(vrfy, vrfy, rsa->n))
 861                 goto err;
 862         if (!BN_is_zero(vrfy)) {
 863             /*
 864              * 'I' and 'vrfy' aren't congruent mod n. Don't leak
 865              * miscalculated CRT output, just do a raw (slower) mod_exp and
 866              * return that instead.
 867              */
 868
 869             BIGNUM local_d;
 870             BIGNUM *d = NULL;
 871
 872             if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 873                 d = &local_d;
 874                 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
 875             } else
 876                 d = rsa->d;
 877             if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
 878                                        rsa->_method_mod_n))
 879                 goto err;
 880         }
 881     }
 882     ret = 1;
 883  err:
 884     BN_CTX_end(ctx);
 885     return (ret);
 886 }
 887
 888 static int RSA_eay_init(RSA *rsa)
 889 {
 890     rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
 891     return (1);
 892 }
 893
 894 static int RSA_eay_finish(RSA *rsa)
 895 {
 896     if (rsa->_method_mod_n != NULL)
 897         BN_MONT_CTX_free(rsa->_method_mod_n);
 898     if (rsa->_method_mod_p != NULL)
 899         BN_MONT_CTX_free(rsa->_method_mod_p);
 900     if (rsa->_method_mod_q != NULL)
 901         BN_MONT_CTX_free(rsa->_method_mod_q);
 902     return (1);
 903 }
 904
 905 #endif