mbedtls/library/ecdh.c
Manuel Pégourié-Gonnard 6545ca7bed Add ECDH primitives
2013-01-26 19:11:24 +01:00

90 lines
2.1 KiB
C

/*
* Elliptic curve Diffie-Hellman
*
* Copyright (C) 2006-2013, Brainspark B.V.
*
* This file is part of PolarSSL (http://www.polarssl.org)
* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
* References:
*
* SEC1 http://www.secg.org/index.php?action=secg,docs_secg
*/
#include "polarssl/config.h"
#if defined(POLARSSL_ECP_C)
#include "polarssl/ecdh.h"
/*
* Generate public key: simple wrapper around ecp_gen_keypair
*/
int ecdh_gen_public( const ecp_group *grp, mpi *d, ecp_point *Q,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
return ecp_gen_keypair( grp, d, Q, f_rng, p_rng );
}
/*
* Compute shared secret (SEC1 3.3.1)
*/
int ecdh_compute_shared( const ecp_group *grp, mpi *z,
const ecp_point *Q, const mpi *d )
{
int ret;
ecp_point P;
ecp_point_init( &P );
/*
* Make sure Q is a valid pubkey before using it
*/
MPI_CHK( ecp_check_pubkey( grp, Q ) );
MPI_CHK( ecp_mul( grp, &P, d, Q ) );
if( ecp_is_zero( &P ) )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
MPI_CHK( mpi_copy( z, &P.X ) );
cleanup:
ecp_point_free( &P );
return( ret );
}
#if defined(POLARSSL_SELF_TEST)
/*
* Checkup routine
*/
int ecdh_self_test( int verbose )
{
return( verbose++ );
}
#endif
#endif /* defined(POLARSSL_ECP_C) */