dsa-keygen.c

/* dsa-keygen.c
 *
 * Generation of DSA keypairs
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2002 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

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

#include "dsa.h"

#include "bignum.h"
#include "memxor.h"
#include "nettle-internal.h"


/* Valid sizes, according to FIPS 186-3 are (1024, 160), (2048. 224),
   (2048, 256), (3072, 256). Currenty, we use only q_bits of 160 or
   256. */
int
dsa_generate_keypair(struct dsa_public_key *pub,
		     struct dsa_private_key *key,
		     void *random_ctx, nettle_random_func random,
		     void *progress_ctx, nettle_progress_func progress,
		     unsigned p_bits, unsigned q_bits)
{
  mpz_t p0, p0q, r;
  unsigned p0_bits;
  unsigned a;

  switch (q_bits)
    {
    case 160:
      if (p_bits < 512)
	return 0;
      break;
    case 256:
      if (p_bits < 1024)
	return 0;
      break;
    default:
      return 0;
    }

  mpz_init (p0);
  mpz_init (p0q);
  mpz_init (r);