rsa-decrypt-tr.c 1.61 KB
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/* rsa-decrypt-tr.c
 *
 * RSA decryption, using randomized RSA blinding to be more resistant
 * to timing attacks.
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2001, 2012 Niels Möller, Nikos Mavrogiannopoulos
 *  
 * The nettle library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 * 
 * The nettle library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with the nettle library; see the file COPYING.LIB.  If not, write to
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 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02111-1301, USA.
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 */

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include "rsa.h"

#include "bignum.h"
#include "pkcs1.h"

int
rsa_decrypt_tr(const struct rsa_public_key *pub,
	       const struct rsa_private_key *key,
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	       void *random_ctx, nettle_random_func *random,
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	       size_t *length, uint8_t *message,
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	       const mpz_t gibberish)
{
  mpz_t m, ri;
  int res;

  mpz_init_set(m, gibberish);
  mpz_init (ri);

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  _rsa_blind (pub, random_ctx, random, m, ri);
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  rsa_compute_root(key, m, m);
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  _rsa_unblind (pub, m, ri);
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  mpz_clear (ri);

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  res = pkcs1_decrypt (key->size, m, length, message);
  mpz_clear(m);
  return res;
}