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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"
#define DSA_MIN_P_BITS 512
#define DSA_Q_OCTETS 20
#define DSA_Q_BITS 160
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, private key operations will need both
* the private and the public information. */
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_sign(const struct dsa_public_key *pub,
const struct dsa_private_key *key,
void *random_ctx, nettle_random_func random,
struct sha1_ctx *hash,
struct dsa_signature *signature);
int
dsa_verify(const struct dsa_public_key *key,
struct sha1_ctx *hash,
const struct dsa_signature *signature);
void
dsa_sign_digest(const struct dsa_public_key *pub,
const struct dsa_private_key *key,
void *random_ctx, nettle_random_func random,
const uint8_t *digest,
struct dsa_signature *signature);
int
dsa_verify_digest(const struct dsa_public_key *key,
const uint8_t *digest,
const struct dsa_signature *signature);
/* Key generation */
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,
/* Size of key, in bits.
* Use size = 512 + 64 * l for the official
* NIS key sizes. */
unsigned bits);
struct sexp_iterator;
int
dsa_signature_from_sexp(struct dsa_signature *rs,
struct sexp_iterator *i);
int
dsa_keypair_from_sexp_alist(struct dsa_public_key *pub,
struct dsa_private_key *priv,
unsigned limit,
struct sexp_iterator *i);
/* If PRIV is NULL, expect a public-key expression. If PUB is NULL,
* expect a private key expression and ignore the parts not needed for
* the public key. */
/* Keys must be initialized before calling this function, as usual. */
int
dsa_keypair_from_sexp(struct dsa_public_key *pub,
struct dsa_private_key *priv,
unsigned limit,
unsigned length, const uint8_t *expr);
#endif /* NETTLE_DSA_H_INCLUDED */
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