forked from xuos/xiuos
284 lines
9.7 KiB
C
284 lines
9.7 KiB
C
/**
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* \file ecdh.h
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*
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* \brief The Elliptic Curve Diffie-Hellman (ECDH) protocol APIs.
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*
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* ECDH is an anonymous key agreement protocol allowing two parties to
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* establish a shared secret over an insecure channel. Each party must have an
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* elliptic-curve public–private key pair.
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*
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* For more information, see <em>NIST SP 800-56A Rev. 2: Recommendation for
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* Pair-Wise Key Establishment Schemes Using Discrete Logarithm
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* Cryptography</em>.
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*/
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/*
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* Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is part of Mbed TLS (https://tls.mbed.org)
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*/
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#ifndef MBEDTLS_ECDH_H
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#define MBEDTLS_ECDH_H
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#include "ecp.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* Defines the source of the imported EC key:
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* <ul><li>Our key.</li>
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* <li>The key of the peer.</li></ul>
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*/
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typedef enum
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{
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MBEDTLS_ECDH_OURS,
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MBEDTLS_ECDH_THEIRS,
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} mbedtls_ecdh_side;
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/**
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* \brief The ECDH context structure.
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*/
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typedef struct
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{
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mbedtls_ecp_group grp; /*!< The elliptic curve used. */
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mbedtls_mpi d; /*!< The private key. */
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mbedtls_ecp_point Q; /*!< The public key. */
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mbedtls_ecp_point Qp; /*!< The value of the public key of the peer. */
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mbedtls_mpi z; /*!< The shared secret. */
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int point_format; /*!< The format of point export in TLS messages. */
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mbedtls_ecp_point Vi; /*!< The blinding value. */
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mbedtls_ecp_point Vf; /*!< The unblinding value. */
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mbedtls_mpi _d; /*!< The previous \p d. */
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}
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mbedtls_ecdh_context;
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/**
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* \brief This function generates an ECDH keypair on an elliptic
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* curve.
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*
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* This function performs the first of two core computations
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* implemented during the ECDH key exchange. The second core
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* computation is performed by mbedtls_ecdh_compute_shared().
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*
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* \param grp The ECP group.
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* \param d The destination MPI (private key).
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* \param Q The destination point (public key).
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* \param f_rng The RNG function.
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* \param p_rng The RNG parameter.
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*
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* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX or
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* \c MBEDTLS_MPI_XXX error code on failure.
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*
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* \see ecp.h
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*/
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int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng );
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/**
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* \brief This function computes the shared secret.
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*
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* This function performs the second of two core computations
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* implemented during the ECDH key exchange. The first core
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* computation is performed by mbedtls_ecdh_gen_public().
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*
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* \param grp The ECP group.
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* \param z The destination MPI (shared secret).
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* \param Q The public key from another party.
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* \param d Our secret exponent (private key).
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* \param f_rng The RNG function.
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* \param p_rng The RNG parameter.
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*
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* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX or
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* \c MBEDTLS_MPI_XXX error code on failure.
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*
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* \see ecp.h
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*
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* \note If \p f_rng is not NULL, it is used to implement
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* countermeasures against potential elaborate timing
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* attacks. For more information, see mbedtls_ecp_mul().
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*/
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int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
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const mbedtls_ecp_point *Q, const mbedtls_mpi *d,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng );
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/**
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* \brief This function initializes an ECDH context.
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*
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* \param ctx The ECDH context to initialize.
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*/
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void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx );
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/**
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* \brief This function frees a context.
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*
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* \param ctx The context to free.
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*/
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void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx );
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/**
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* \brief This function generates a public key and a TLS
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* ServerKeyExchange payload.
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*
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* This is the first function used by a TLS server for ECDHE
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* ciphersuites.
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*
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* \param ctx The ECDH context.
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* \param olen The number of characters written.
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* \param buf The destination buffer.
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* \param blen The length of the destination buffer.
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* \param f_rng The RNG function.
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* \param p_rng The RNG parameter.
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*
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* \note This function assumes that the ECP group (grp) of the
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* \p ctx context has already been properly set,
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* for example, using mbedtls_ecp_group_load().
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*
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* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX error code
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* on failure.
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*
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* \see ecp.h
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*/
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int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
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unsigned char *buf, size_t blen,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng );
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/**
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* \brief This function parses and processes a TLS ServerKeyExhange
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* payload.
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*
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* This is the first function used by a TLS client for ECDHE
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* ciphersuites.
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*
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* \param ctx The ECDH context.
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* \param buf The pointer to the start of the input buffer.
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* \param end The address for one Byte past the end of the buffer.
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*
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* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX error code
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* on failure.
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*
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* \see ecp.h
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*/
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int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
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const unsigned char **buf, const unsigned char *end );
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/**
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* \brief This function sets up an ECDH context from an EC key.
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*
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* It is used by clients and servers in place of the
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* ServerKeyEchange for static ECDH, and imports ECDH
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* parameters from the EC key information of a certificate.
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*
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* \param ctx The ECDH context to set up.
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* \param key The EC key to use.
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* \param side Defines the source of the key:
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* <ul><li>1: Our key.</li>
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<li>0: The key of the peer.</li></ul>
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*
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* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX error code
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* on failure.
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*
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* \see ecp.h
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*/
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int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key,
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mbedtls_ecdh_side side );
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/**
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* \brief This function generates a public key and a TLS
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* ClientKeyExchange payload.
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*
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* This is the second function used by a TLS client for ECDH(E)
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* ciphersuites.
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*
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* \param ctx The ECDH context.
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* \param olen The number of Bytes written.
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* \param buf The destination buffer.
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* \param blen The size of the destination buffer.
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* \param f_rng The RNG function.
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* \param p_rng The RNG parameter.
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*
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* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX error code
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* on failure.
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*
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* \see ecp.h
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*/
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int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
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unsigned char *buf, size_t blen,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng );
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/**
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* \brief This function parses and processes a TLS ClientKeyExchange
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* payload.
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*
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* This is the second function used by a TLS server for ECDH(E)
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* ciphersuites.
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*
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* \param ctx The ECDH context.
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* \param buf The start of the input buffer.
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* \param blen The length of the input buffer.
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*
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* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX error code
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* on failure.
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*
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* \see ecp.h
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*/
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int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
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const unsigned char *buf, size_t blen );
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/**
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* \brief This function derives and exports the shared secret.
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*
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* This is the last function used by both TLS client
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* and servers.
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*
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* \param ctx The ECDH context.
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* \param olen The number of Bytes written.
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* \param buf The destination buffer.
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* \param blen The length of the destination buffer.
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* \param f_rng The RNG function.
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* \param p_rng The RNG parameter.
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*
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* \return \c 0 on success, or an \c MBEDTLS_ERR_ECP_XXX error code
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* on failure.
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*
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* \see ecp.h
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*
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* \note If \p f_rng is not NULL, it is used to implement
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* countermeasures against potential elaborate timing
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* attacks. For more information, see mbedtls_ecp_mul().
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*/
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int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
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unsigned char *buf, size_t blen,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng );
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#ifdef __cplusplus
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}
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#endif
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#endif /* ecdh.h */
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