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/* dsa.h
*
* The DSA publickey algorithm.
*/
/* 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., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#ifndef NETTLE_DSA_H_INCLUDED
#define NETTLE_DSA_H_INCLUDED
#include <inttypes.h>
#include <gmp.h>
#include "sha.h"
/* For nettle_random_func */
#include "nettle-meta.h"
struct dsa_public_key
{
/* Modulo */
mpz_t p;
/* Group order */
mpz_t q;
/* Generator */
mpz_t g;
/* Public value */
mpz_t y;
};
struct dsa_private_key
{
/* Unlike an rsa public key, all the public information is needed,
* in addition to the private information. */
struct dsa_public_key pub;
mpz_t x;
};
struct dsa_signature
{
mpz_t r;
mpz_t s;
};
/* Signing a message works as follows:
*
* Store the private key in a dsa_private_key struct.
*
* Initialize a hashing context, by callling
* sha1_init
*
* Hash the message by calling
* sha1_update
*
* Create the signature by calling
* dsa_sign
*
* The signature is represented as two mpz_t bignums. This call also
* resets the hashing context.
*
* When done with the key and signature, don't forget to call
* mpz_clear.
*/
/* Calls mpz_init to initialize bignum storage. */
void
dsa_public_key_init(struct dsa_public_key *key);
/* Calls mpz_clear to deallocate bignum storage. */
void
dsa_public_key_clear(struct dsa_public_key *key);
/* Calls mpz_init to initialize bignum storage. */
void
dsa_private_key_init(struct dsa_private_key *key);
/* Calls mpz_clear to deallocate bignum storage. */
void
dsa_private_key_clear(struct dsa_private_key *key);
/* Calls mpz_init to initialize bignum storage. */
void
dsa_signature_init(struct dsa_signature *signature);
/* Calls mpz_clear to deallocate bignum storage. */
void
dsa_signature_clear(struct dsa_signature *signature);
void
_dsa_hash(mpz_t x, struct sha1_ctx *hash);
void
dsa_sign(struct dsa_private_key *key,
void *random_ctx, nettle_random_func random,
struct sha1_ctx *hash,
struct dsa_signature *signature);
int
dsa_verify(struct dsa_public_key *key,
struct sha1_ctx *hash,
const struct dsa_signature *signature);
/* Key generation */
#if 0
/* Note that the key structs must be initialized first. */
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,
/* Desired size of modulo, in bits */
unsigned n_size,
/* Desired size of public exponent, in bits. If
* zero, the passed in value pub->e is used. */
unsigned e_size);
#define DSA_SIGN(key, algorithm, ctx, length, data, signature) ( \
algorithm##_update(ctx, length, data), \
dsa_##algorithm##_sign(key, ctx, signature) \
)
#define DSA_VERIFY(key, algorithm, ctx, length, data, signature) ( \
algorithm##_update(ctx, length, data), \
dsa_##algorithm##_verify(key, ctx, signature) \
)
#endif
#endif /* NETTLE_DSA_H_INCLUDED */
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