path: root/lib/auth_dhe.c

/*
 *  Copyright (C) 2000,2001,2002,2003 Nikos Mavroyanopoulos
 *  Copyright (C) 2004 Free Software Foundation
 *
 *  This file is part of GNUTLS.
 *
 *  The GNUTLS 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.
 *
 *  This 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 this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 * 
 */

/* This file contains everything for the Ephemeral Diffie Hellman (DHE)
 * key exchange. This is used in the handshake procedure of the certificate
 * authentication.
 */

#include "gnutls_int.h"
#include "gnutls_auth_int.h"
#include "gnutls_errors.h"
#include "gnutls_dh.h"
#include "gnutls_num.h"
#include "gnutls_sig.h"
#include <gnutls_datum.h>
#include <auth_cert.h>
#include <gnutls_x509.h>
#include <gnutls_extra.h>
#include <gnutls_state.h>
#include <auth_dh_common.h>

static int gen_dhe_server_kx(gnutls_session, opaque **);
static int proc_dhe_server_kx(gnutls_session, opaque *, size_t);
static int proc_dhe_client_kx(gnutls_session, opaque *, size_t);

const MOD_AUTH_STRUCT dhe_rsa_auth_struct = {
	"DHE_RSA",
	_gnutls_gen_cert_server_certificate,
	_gnutls_gen_cert_client_certificate,
	gen_dhe_server_kx,
	_gnutls_gen_dh_common_client_kx,
	_gnutls_gen_cert_client_cert_vrfy,	/* gen client cert vrfy */
	_gnutls_gen_cert_server_cert_req,	/* server cert request */

	_gnutls_proc_cert_server_certificate,
	_gnutls_proc_cert_client_certificate,
	proc_dhe_server_kx,
	proc_dhe_client_kx,
	_gnutls_proc_cert_client_cert_vrfy,	/* proc client cert vrfy */
	_gnutls_proc_cert_cert_req	/* proc server cert request */
};

const MOD_AUTH_STRUCT dhe_dss_auth_struct = {
	"DHE_DSS",
	_gnutls_gen_cert_server_certificate,
	_gnutls_gen_cert_client_certificate,
	gen_dhe_server_kx,
	_gnutls_gen_dh_common_client_kx,
	_gnutls_gen_cert_client_cert_vrfy,	/* gen client cert vrfy */
	_gnutls_gen_cert_server_cert_req,	/* server cert request */

	_gnutls_proc_cert_server_certificate,
	_gnutls_proc_cert_client_certificate,
	proc_dhe_server_kx,
	proc_dhe_client_kx,
	_gnutls_proc_cert_client_cert_vrfy,	/* proc client cert vrfy */
	_gnutls_proc_cert_cert_req	/* proc server cert request */
};


static int gen_dhe_server_kx(gnutls_session session, opaque ** data)
{
	GNUTLS_MPI g, p;
	const GNUTLS_MPI *mpis;
	int ret = 0, data_size;
	int bits;
	gnutls_cert *apr_cert_list;
	gnutls_privkey* apr_pkey;
	int apr_cert_list_length;
	gnutls_datum signature, ddata;
	CERTIFICATE_AUTH_INFO info;
	const gnutls_certificate_credentials cred;
	gnutls_dh_params dh_params;

	cred = _gnutls_get_cred(session->key, GNUTLS_CRD_CERTIFICATE, NULL);
	if (cred == NULL) {
	        gnutls_assert();
	        return GNUTLS_E_INSUFFICIENT_CREDENTIALS;
	}

	bits = _gnutls_dh_get_allowed_prime_bits( session);

	/* find the appropriate certificate */
	if ((ret =
	     _gnutls_get_selected_cert(session, &apr_cert_list,
				   &apr_cert_list_length,
				   &apr_pkey)) < 0) {
		gnutls_assert();
		return ret;
	}

	dh_params = _gnutls_certificate_get_dh_params( cred, session);
	mpis = _gnutls_get_dh_params( dh_params);
	if (mpis == NULL) {
		gnutls_assert();
		return GNUTLS_E_NO_TEMPORARY_DH_PARAMS;
	}

	p = mpis[0];
	g = mpis[1];

	if ( (ret=_gnutls_auth_info_set( session, GNUTLS_CRD_CERTIFICATE, 
		sizeof( CERTIFICATE_AUTH_INFO_INT), 0)) < 0) 
	{
		gnutls_assert();
		return ret;
	}

	info = _gnutls_get_auth_info( session);
	ret=_gnutls_dh_set_prime( session, g, p);
	if (ret<0) {
		gnutls_assert();
		return ret;
	}

	ret = _gnutls_dh_common_print_server_kx( session, g, p, data);

	if (ret < 0) {
		gnutls_assert();
		return ret;
	}
	data_size = ret;

	/* Generate the signature. */

	ddata.data = *data;
	ddata.size = data_size;

	if (apr_pkey != NULL) {
		if ((ret =
		     _gnutls_tls_sign_params(session, &apr_cert_list[0],
						 apr_pkey, &ddata,
						 &signature)) < 0) {
			gnutls_assert();
			gnutls_free(*data);
			return ret;
		}
	} else {
		gnutls_assert();
		return data_size;	/* do not put a signature - ILLEGAL! */
	}

	*data = gnutls_realloc_fast(*data, data_size + signature.size + 2);
	if (*data == NULL) {
		_gnutls_free_datum(&signature);
		gnutls_assert();
		return GNUTLS_E_MEMORY_ERROR;
	}

	_gnutls_write_datum16(&(*data)[data_size], signature);
	data_size += signature.size + 2;

	_gnutls_free_datum(&signature);

	return data_size;
}

static int proc_dhe_server_kx(gnutls_session session, opaque * data,
				  size_t _data_size)
{
	int sigsize;
	gnutls_datum vparams, signature;
	int ret;
	CERTIFICATE_AUTH_INFO info = _gnutls_get_auth_info( session);
	ssize_t data_size = _data_size;
	gnutls_cert peer_cert;

	if (info == NULL || info->ncerts==0) {
		gnutls_assert();
		/* we need this in order to get peer's certificate */
		return GNUTLS_E_INTERNAL_ERROR;
	}

	ret = _gnutls_proc_dh_common_server_kx( session, data, _data_size);
	if (ret < 0) {
		gnutls_assert();
		return ret;
	}

	/* VERIFY SIGNATURE */

	vparams.size = ret;
	vparams.data = data;

	DECR_LEN( data_size, 2);
	sigsize = _gnutls_read_uint16(&data[vparams.size]);

	DECR_LEN( data_size, sigsize);
	signature.data = &data[vparams.size + 2];
	signature.size = sigsize;

	if ((ret =
	     _gnutls_raw_cert_to_gcert( &peer_cert, session->security_parameters.cert_type,
				     &info->raw_certificate_list[0], CERT_NO_COPY)) < 0) {
		gnutls_assert();
		return ret;
	}

	ret =
	    _gnutls_verify_sig_params(session,
				      &peer_cert,
				      &vparams, &signature);
	
	_gnutls_gcert_deinit( &peer_cert);
	if (ret < 0) {
		gnutls_assert();
		return ret;
	}

	return ret;
}



static int proc_dhe_client_kx(gnutls_session session, opaque * data,
				  size_t _data_size)
{
const gnutls_certificate_credentials cred;
int ret;
GNUTLS_MPI p, g;
const GNUTLS_MPI *mpis;
gnutls_dh_params dh_params;

	cred = _gnutls_get_cred(session->key, GNUTLS_CRD_CERTIFICATE, NULL);
	if (cred == NULL) {
	        gnutls_assert();
	        return GNUTLS_E_INSUFFICIENT_CREDENTIALS;
	}

	dh_params = _gnutls_certificate_get_dh_params( cred, session);
	mpis = _gnutls_get_dh_params( dh_params);
	if (mpis == NULL) {
		gnutls_assert();
		return GNUTLS_E_NO_TEMPORARY_DH_PARAMS;
	}

	p = mpis[0];
	g = mpis[1];

	ret = _gnutls_proc_dh_common_client_kx( session, data, _data_size, g, p);
	
	return ret;

}