c-libp2p/include/mbedtls/ecdh.h
2016-11-03 11:15:18 -05:00

214 lines
7.6 KiB
C

/**
* \file ecdh.h
*
* \brief Elliptic curve Diffie-Hellman
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#ifndef MBEDTLS_ECDH_H
#define MBEDTLS_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
{
MBEDTLS_ECDH_OURS,
MBEDTLS_ECDH_THEIRS,
} mbedtls_ecdh_side;
/**
* \brief ECDH context structure
*/
typedef struct
{
mbedtls_ecp_group grp; /*!< elliptic curve used */
mbedtls_mpi d; /*!< our secret value (private key) */
mbedtls_ecp_point Q; /*!< our public value (public key) */
mbedtls_ecp_point Qp; /*!< peer's public value (public key) */
mbedtls_mpi z; /*!< shared secret */
int point_format; /*!< format for point export in TLS messages */
mbedtls_ecp_point Vi; /*!< blinding value (for later) */
mbedtls_ecp_point Vf; /*!< un-blinding value (for later) */
mbedtls_mpi _d; /*!< previous d (for later) */
}
mbedtls_ecdh_context;
/**
* \brief Generate a public key.
* Raw function that only does the core computation.
*
* \param grp ECP group
* \param d Destination MPI (secret exponent, aka private key)
* \param Q Destination point (public key)
* \param f_rng RNG function
* \param p_rng RNG parameter
*
* \return 0 if successful,
* or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code
*/
int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \brief Compute shared secret
* Raw function that only does the core computation.
*
* \param grp ECP group
* \param z Destination MPI (shared secret)
* \param Q Public key from other party
* \param d Our secret exponent (private key)
* \param f_rng RNG function (see notes)
* \param p_rng RNG parameter
*
* \return 0 if successful,
* or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code
*
* \note If f_rng is not NULL, it is used to implement
* countermeasures against potential elaborate timing
* attacks, see \c mbedtls_ecp_mul() for details.
*/
int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
const mbedtls_ecp_point *Q, const mbedtls_mpi *d,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \brief Initialize context
*
* \param ctx Context to initialize
*/
void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx );
/**
* \brief Free context
*
* \param ctx Context to free
*/
void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx );
/**
* \brief Generate a public key and a TLS ServerKeyExchange payload.
* (First function used by a TLS server for ECDHE.)
*
* \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 mbedtls_ecp_group_load).
*
* \return 0 if successful, or an MBEDTLS_ERR_ECP_XXX error code
*/
int mbedtls_ecdh_make_params( mbedtls_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 procress a TLS ServerKeyExhange payload.
* (First function used by a TLS client for ECDHE.)
*
* \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 MBEDTLS_ERR_ECP_XXX error code
*/
int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
const unsigned char **buf, const unsigned char *end );
/**
* \brief Setup an ECDH context from an EC key.
* (Used by clients and servers in place of the
* ServerKeyEchange for static ECDH: import ECDH parameters
* from a certificate's EC key information.)
*
* \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 MBEDTLS_ERR_ECP_XXX error code
*/
int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key,
mbedtls_ecdh_side side );
/**
* \brief Generate a public key and a TLS ClientKeyExchange payload.
* (Second function used by a TLS client for ECDH(E).)
*
* \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 MBEDTLS_ERR_ECP_XXX error code
*/
int mbedtls_ecdh_make_public( mbedtls_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 process a TLS ClientKeyExchange payload.
* (Second function used by a TLS server for ECDH(E).)
*
* \param ctx ECDH context
* \param buf start of input buffer
* \param blen length of input buffer
*
* \return 0 if successful, or an MBEDTLS_ERR_ECP_XXX error code
*/
int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
const unsigned char *buf, size_t blen );
/**
* \brief Derive and export the shared secret.
* (Last function used by both TLS client en servers.)
*
* \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 mbedtls_ecdh_compute_shared()
* \param p_rng RNG parameter
*
* \return 0 if successful, or an MBEDTLS_ERR_ECP_XXX error code
*/
int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
unsigned char *buf, size_t blen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
#ifdef __cplusplus
}
#endif
#endif /* ecdh.h */