release/src/router/nettle/rsa-decrypt-tr.c

   1 /* rsa-decrypt-tr.c
   2  *
   3  * RSA decryption, using randomized RSA blinding to be more resistant
   4  * to timing attacks.
   5  */
   6
   7 /* nettle, low-level cryptographics library
   8  *
   9  * Copyright (C) 2001, 2012 Niels Möller, Nikos Mavrogiannopoulos
  10  *
  11  * The nettle library is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU Lesser General Public License as published by
  13  * the Free Software Foundation; either version 2.1 of the License, or (at your
  14  * option) any later version.
  15  *
  16  * The nettle library is distributed in the hope that it will be useful, but
  17  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  18  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  19  * License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public License
  22  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  23  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  24  * MA 02111-1301, USA.
  25  */
  26
  27 #if HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include "rsa.h"
  32
  33 #include "bignum.h"
  34 #include "pkcs1.h"
  35
  36 int
  37 rsa_decrypt_tr(const struct rsa_public_key *pub,
  38                const struct rsa_private_key *key,
  39                void *random_ctx, nettle_random_func *random,
  40                unsigned *length, uint8_t *message,
  41                const mpz_t gibberish)
  42 {
  43   mpz_t m, ri;
  44   int res;
  45
  46   mpz_init_set(m, gibberish);
  47   mpz_init (ri);
  48
  49   _rsa_blind (pub, random_ctx, random, m, ri);
  50   rsa_compute_root(key, m, m);
  51   _rsa_unblind (pub, m, ri);
  52   mpz_clear (ri);
  53
  54   res = pkcs1_decrypt (key->size, m, length, message);
  55   mpz_clear(m);
  56   return res;
  57 }