/usr/include/polarssl/ecdh.h is in libpolarssl-dev 1.3.4-1.
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* \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 "ecp.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* When importing from an EC key, select if it is our key or the peer's key
*/
typedef enum
{
POLARSSL_ECDH_OURS,
POLARSSL_ECDH_THEIRS,
} ecdh_side;
/**
* \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 */
int point_format; /*!< format for point export */
ecp_point Vi; /*!< blinding value (for later) */
ecp_point Vf; /*!< un-blinding value (for later) */
mpi _d; /*!< previous d */
}
ecdh_context;
/**
* \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( 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
* \param f_rng RNG function (see notes)
* \param p_rng RNG parameter
*
* \return 0 if successful,
* or a POLARSSL_ERR_ECP_XXX or POLARSSL_MPI_XXX error code
*
* \note If f_rng is not NULL, it is used to implement
* countermeasures against potential elaborate timing
* attacks, see \c ecp_mul() for details.
*/
int ecdh_compute_shared( ecp_group *grp, mpi *z,
const ecp_point *Q, const mpi *d,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \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 Setup and write the ServerKeyExhange parameters
*
* \param ctx ECDH context
* \param olen number of chars written
* \param buf destination buffer
* \param blen length of buffer
* \param f_rng RNG function
* \param p_rng RNG parameter
*
* \note This function assumes that ctx->grp has already been
* properly set (for example using ecp_use_known_dp).
*
* \return 0 if successful, or an POLARSSL_ERR_ECP_XXX error code
*/
int ecdh_make_params( ecdh_context *ctx, size_t *olen,
unsigned char *buf, size_t blen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \brief Parse the ServerKeyExhange parameters
*
* \param ctx ECDH context
* \param buf pointer to start of input buffer
* \param end one past end of buffer
*
* \return 0 if successful, or an POLARSSL_ERR_ECP_XXX error code
*/
int ecdh_read_params( ecdh_context *ctx,
const unsigned char **buf, const unsigned char *end );
/**
* \brief Setup an ECDH context from an EC key
*
* \param ctx ECDH constext to set
* \param key EC key to use
* \param side Is it our key (1) or the peer's key (0) ?
*
* \return 0 if successful, or an POLARSSL_ERR_ECP_XXX error code
*/
int ecdh_get_params( ecdh_context *ctx, const ecp_keypair *key,
ecdh_side side );
/**
* \brief Setup and export the client's public value
*
* \param ctx ECDH context
* \param olen number of bytes actually written
* \param buf destination buffer
* \param blen size of destination buffer
* \param f_rng RNG function
* \param p_rng RNG parameter
*
* \return 0 if successful, or an POLARSSL_ERR_ECP_XXX error code
*/
int ecdh_make_public( ecdh_context *ctx, size_t *olen,
unsigned char *buf, size_t blen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \brief Parse and import the client's public value
*
* \param ctx ECDH context
* \param buf start of input buffer
* \param blen length of input buffer
*
* \return 0 if successful, or an POLARSSL_ERR_ECP_XXX error code
*/
int ecdh_read_public( ecdh_context *ctx,
const unsigned char *buf, size_t blen );
/**
* \brief Derive and export the shared secret
*
* \param ctx ECDH context
* \param olen number of bytes written
* \param buf destination buffer
* \param blen buffer length
* \param f_rng RNG function, see notes for \c ecdh_compute_shared()
* \param p_rng RNG parameter
*
* \return 0 if successful, or an POLARSSL_ERR_ECP_XXX error code
*/
int ecdh_calc_secret( ecdh_context *ctx, size_t *olen,
unsigned char *buf, size_t blen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \brief Checkup routine
*
* \return 0 if successful, or 1 if the test failed
*/
int ecdh_self_test( int verbose );
#ifdef __cplusplus
}
#endif
#endif
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