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/* rsa.c
*
* The RSA publickey algorithm.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001 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., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#if WITH_PUBLIC_KEY
#include "rsa.h"
#include "bignum.h"
/* FIXME: Perhaps we should split this into several functions, so that
* one can link in the signature functions without also getting the
* verify functions. */
void
rsa_public_key_init(struct rsa_public_key *key)
{
mpz_init(key->n);
mpz_init(key->e);
/* Not really necessary, but it seems cleaner to initialize all the
* storage. */
key->size = 0;
}
void
rsa_public_key_clear(struct rsa_public_key *key)
{
mpz_clear(key->n);
mpz_clear(key->e);
}
/* Computes the size, in octets, of a the modulo. Returns 0 if the
* modulo is too small to be useful. */
unsigned
_rsa_check_size(mpz_t n)
{
/* Round upwards */
unsigned size = (mpz_sizeinbase(n, 2) + 7) / 8;
if (size < RSA_MINIMUM_N_OCTETS)
return 0;
return size;
}
int
rsa_public_key_prepare(struct rsa_public_key *key)
{
/* FIXME: Add further sanity checks, like 0 < e < n. */
#if 0
if ( (mpz_sgn(key->e) <= 0)
|| mpz_cmp(key->e, key->n) >= 0)
return 0;
#endif
key->size = _rsa_check_size(key->n);
return (key->size > 0);
}
#endif /* WITH_PUBLIC_KEY */
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