rsa_sha1.c

/* rsa_sha1.c
 *
 * Signatures using RSA and SHA1.
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2001 Niels Mller
 *  
 * 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
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

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

#if HAVE_LIBGMP

#include "rsa.h"

#include "bignum.h"

#include <assert.h>
#include <stdlib.h>
#include <string.h>

/* Forward declarations */
static void
pkcs1_encode_sha1(mpz_t m, unsigned length, struct sha1_ctx *hash);

void
rsa_sha1_sign(struct rsa_private_key *key,
              struct sha1_ctx *hash,
              mpz_t s)
{
  assert(key->size >= 45);

  pkcs1_encode_sha1(s, key->size - 1, hash);

  rsa_compute_root(key, s, s);
}

int
rsa_sha1_verify(struct rsa_public_key *key,
                struct sha1_ctx *hash,
                const mpz_t s)
{
  int res;
  
  mpz_t m1;
  mpz_t m2;

  if ( (mpz_sgn(s) <= 0)
       || (mpz_cmp(s, key->n) >= 0) )
    return 0;

  mpz_init(m1); mpz_init(m2);