include/polarssl/ecdh.h

/**
 * \file ecdh.h
 *
 * \brief 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.
 */
#ifndef POLARSSL_ECDH_H
#define POLARSSL_ECDH_H

#include "polarssl/ecp.h"

/**
 * \brief           ECDH context structure
 */
typedef struct
{
    ecp_group grp;  /*!<  ellipitic curve used  */
    mpi d;          /*!<  our secret value      */
    ecp_point Q;    /*!<  our public value      */
    ecp_point Qp;   /*!<  peer's public value   */
    mpi z;          /*!<  shared secret         */
}
ecdh_context;

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \brief           Generate a public key
 *
 * \param grp       ECP group
 * \param d         Destination MPI (secret exponent)
 * \param Q         Destination point (public key)
 * \param f_rng     RNG function
 * \param p_rng     RNG parameter
 *
 * \return          0 if successful,
 *                  or a POLARSSL_ERR_ECP_XXX or POLARSSL_MPI_XXX error code
 */
int ecdh_gen_public( const ecp_group *grp, mpi *d, ecp_point *Q,
                     int (*f_rng)(void *, unsigned char *, size_t),
                     void *p_rng );

/**
 * \brief           Compute shared secret
 *
 * \param grp       ECP group
 * \param z         Destination MPI (shared secret)
 * \param Q         Public key from other party
 * \param d         Our secret exponent
 *
 * \return          0 if successful,
 *                  or a POLARSSL_ERR_ECP_XXX or POLARSSL_MPI_XXX error code
 */
int ecdh_compute_shared( const ecp_group *grp, mpi *z,
                         const ecp_point *Q, const mpi *d );

/**
 * \brief           Initialize context
 *
 * \param ctx       Context to initialize
 */
void ecdh_init( ecdh_context *ctx );

/**
 * \brief           Free context
 *
 * \param ctx       Context to free
 */
void ecdh_free( ecdh_context *ctx );

/**
 * \brief          Checkup routine
 *
 * \return         0 if successful, or 1 if the test failed
 */
int ecdh_self_test( int verbose );

#ifdef __cplusplus
}
#endif

#endif