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/* sexp2dsa.c
*
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2002 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 <string.h>
#include "dsa.h"
#include "bignum.h"
#include "sexp.h"
#define GET(x, l, v) \
do { \
if (!nettle_mpz_set_sexp((x), (l), (v)) \
|| mpz_sgn(x) <= 0) \
return 0; \
} while(0)
/* Iterator should point past the algorithm tag, e.g.
*
* (public-key (dsa (p |xxxx|) ...)
* ^ here
*/
int
dsa_keypair_from_sexp_alist(struct dsa_params *params,
mpz_t pub,
mpz_t priv,
unsigned p_max_bits,
unsigned q_bits,
struct sexp_iterator *i)
{
static const uint8_t * const names[5]
= { "p", "q", "g", "y", "x" };
struct sexp_iterator values[5];
unsigned nvalues = priv ? 5 : 4;
unsigned p_bits;
if (!sexp_iterator_assoc(i, nvalues, names, values))
return 0;
GET(params->p, p_max_bits, &values[0]);
p_bits = mpz_sizeinbase (params->p, 2);
GET(params->q, q_bits ? q_bits : p_bits, &values[1]);
if (q_bits > 0 && mpz_sizeinbase(params->q, 2) != q_bits)
return 0;
if (mpz_cmp (params->q, params->p) >= 0)
return 0;
GET(params->g, p_bits, &values[2]);
if (mpz_cmp (params->g, params->p) >= 0)
return 0;
GET(pub, p_bits, &values[3]);
if (mpz_cmp (pub, params->p) >= 0)
return 0;
if (priv)
{
GET(priv, mpz_sizeinbase (params->q, 2), &values[4]);
if (mpz_cmp (priv, params->q) >= 0)
return 0;
}
return 1;
}
int
dsa_sha1_keypair_from_sexp(struct dsa_params *params,
mpz_t pub,
mpz_t priv,
unsigned p_max_bits,
size_t length, const uint8_t *expr)
{
struct sexp_iterator i;
return sexp_iterator_first(&i, length, expr)
&& sexp_iterator_check_type(&i, priv ? "private-key" : "public-key")
&& sexp_iterator_check_type(&i, "dsa")
&& dsa_keypair_from_sexp_alist(params, pub, priv,
p_max_bits, DSA_SHA1_Q_BITS, &i);
}
int
dsa_sha256_keypair_from_sexp(struct dsa_params *params,
mpz_t pub,
mpz_t priv,
unsigned p_max_bits,
size_t length, const uint8_t *expr)
{
struct sexp_iterator i;
return sexp_iterator_first(&i, length, expr)
&& sexp_iterator_check_type(&i, priv ? "private-key" : "public-key")
&& sexp_iterator_check_type(&i, "dsa-sha256")
&& dsa_keypair_from_sexp_alist(params, pub, priv,
p_max_bits, DSA_SHA256_Q_BITS, &i);
}
int
dsa_signature_from_sexp(struct dsa_signature *rs,
struct sexp_iterator *i,
unsigned q_bits)
{
static const uint8_t * const names[2] = { "r", "s" };
struct sexp_iterator values[2];
if (!sexp_iterator_assoc(i, 2, names, values))
return 0;
GET(rs->r, q_bits, &values[0]);
GET(rs->s, q_bits, &values[1]);
return 1;
}
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