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dsa-keygen.c
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dsa-keygen.c 1.52 KiB
/* dsa-keygen.c
*
* Generation of DSA keypairs
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2002, 2014 Niels Möller
*
* 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., 51 Franklin Street, Fifth Floor, Boston,
* MA 02111-1301, USA.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <stdlib.h>
#include "dsa.h"
#include "bignum.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. */
void
dsa_generate_keypair (const struct dsa_params *params,
mpz_t pub, mpz_t key,
void *random_ctx, nettle_random_func *random)
{
mpz_t r;
mpz_init_set(r, params->q);
mpz_sub_ui(r, r, 2);
nettle_mpz_random(key, random_ctx, random, r);
mpz_add_ui(key, key, 1);
mpz_powm(pub, params->g, key, params->p);
mpz_clear (r);
}