| /** |
| * \file ecdh.h |
| * |
| * \brief This file contains ECDH definitions and functions. |
| * |
| * The Elliptic Curve Diffie-Hellman (ECDH) protocol is an anonymous |
| * key agreement protocol allowing two parties to establish a shared |
| * secret over an insecure channel. Each party must have an |
| * elliptic-curve public–private key pair. |
| * |
| * For more information, see <em>NIST SP 800-56A Rev. 2: Recommendation for |
| * Pair-Wise Key Establishment Schemes Using Discrete Logarithm |
| * Cryptography</em>. |
| */ |
| /* |
| * Copyright (C) 2006-2018, Arm Limited (or its affiliates), 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 |
| |
| /** |
| * Defines the source of the imported EC key. |
| */ |
| typedef enum |
| { |
| MBEDTLS_ECDH_OURS, /**< Our key. */ |
| MBEDTLS_ECDH_THEIRS, /**< The key of the peer. */ |
| } mbedtls_ecdh_side; |
| |
| /** |
| * \brief The ECDH context structure. |
| */ |
| typedef struct |
| { |
| mbedtls_ecp_group grp; /*!< The elliptic curve used. */ |
| mbedtls_mpi d; /*!< The private key. */ |
| mbedtls_ecp_point Q; /*!< The public key. */ |
| mbedtls_ecp_point Qp; /*!< The value of the public key of the peer. */ |
| mbedtls_mpi z; /*!< The shared secret. */ |
| int point_format; /*!< The format of point export in TLS messages. */ |
| mbedtls_ecp_point Vi; /*!< The blinding value. */ |
| mbedtls_ecp_point Vf; /*!< The unblinding value. */ |
| mbedtls_mpi _d; /*!< The previous \p d. */ |
| } |
| mbedtls_ecdh_context; |
| |
| /** |
| * \brief This function generates an ECDH keypair on an elliptic |
| * curve. |
| * |
| * This function performs the first of two core computations |
| * implemented during the ECDH key exchange. The second core |
| * computation is performed by mbedtls_ecdh_compute_shared(). |
| * |
| * \see ecp.h |
| * |
| * \param grp The ECP group. |
| * \param d The destination MPI (private key). |
| * \param Q The destination point (public key). |
| * \param f_rng The RNG function. |
| * \param p_rng The RNG context. |
| * |
| * \return \c 0 on success. |
| * \return An \c MBEDTLS_ERR_ECP_XXX or |
| * \c MBEDTLS_MPI_XXX error code on failure. |
| * |
| */ |
| 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 This function computes the shared secret. |
| * |
| * This function performs the second of two core computations |
| * implemented during the ECDH key exchange. The first core |
| * computation is performed by mbedtls_ecdh_gen_public(). |
| * |
| * \see ecp.h |
| * |
| * \note If \p f_rng is not NULL, it is used to implement |
| * countermeasures against side-channel attacks. |
| * For more information, see mbedtls_ecp_mul(). |
| * |
| * \param grp The ECP group. |
| * \param z The destination MPI (shared secret). |
| * \param Q The public key from another party. |
| * \param d Our secret exponent (private key). |
| * \param f_rng The RNG function. |
| * \param p_rng The RNG context. |
| * |
| * \return \c 0 on success. |
| * \return An \c MBEDTLS_ERR_ECP_XXX or |
| * \c MBEDTLS_MPI_XXX error code on failure. |
| */ |
| 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 This function initializes an ECDH context. |
| * |
| * \param ctx The ECDH context to initialize. |
| */ |
| void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx ); |
| |
| /** |
| * \brief This function frees a context. |
| * |
| * \param ctx The context to free. |
| */ |
| void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx ); |
| |
| /** |
| * \brief This function generates a public key and a TLS |
| * ServerKeyExchange payload. |
| * |
| * This is the first function used by a TLS server for ECDHE |
| * ciphersuites. |
| * |
| * \note This function assumes that the ECP group (grp) of the |
| * \p ctx context has already been properly set, |
| * for example, using mbedtls_ecp_group_load(). |
| * |
| * \see ecp.h |
| * |
| * \param ctx The ECDH context. |
| * \param olen The number of characters written. |
| * \param buf The destination buffer. |
| * \param blen The length of the destination buffer. |
| * \param f_rng The RNG function. |
| * \param p_rng The RNG context. |
| * |
| * \return \c 0 on success. |
| * \return An \c MBEDTLS_ERR_ECP_XXX error code on failure. |
| */ |
| 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 This function parses and processes a TLS ServerKeyExhange |
| * payload. |
| * |
| * This is the first function used by a TLS client for ECDHE |
| * ciphersuites. |
| * |
| * \see ecp.h |
| * |
| * \param ctx The ECDH context. |
| * \param buf The pointer to the start of the input buffer. |
| * \param end The address for one Byte past the end of the buffer. |
| * |
| * \return \c 0 on success. |
| * \return An \c MBEDTLS_ERR_ECP_XXX error code on failure. |
| * |
| */ |
| int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx, |
| const unsigned char **buf, const unsigned char *end ); |
| |
| /** |
| * \brief This function sets up an ECDH context from an EC key. |
| * |
| * It is used by clients and servers in place of the |
| * ServerKeyEchange for static ECDH, and imports ECDH |
| * parameters from the EC key information of a certificate. |
| * |
| * \see ecp.h |
| * |
| * \param ctx The ECDH context to set up. |
| * \param key The EC key to use. |
| * \param side Defines the source of the key: 1: Our key, or |
| * 0: The key of the peer. |
| * |
| * \return \c 0 on success. |
| * \return An \c MBEDTLS_ERR_ECP_XXX error code on failure. |
| * |
| */ |
| int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key, |
| mbedtls_ecdh_side side ); |
| |
| /** |
| * \brief This function generates a public key and a TLS |
| * ClientKeyExchange payload. |
| * |
| * This is the second function used by a TLS client for ECDH(E) |
| * ciphersuites. |
| * |
| * \see ecp.h |
| * |
| * \param ctx The ECDH context. |
| * \param olen The number of Bytes written. |
| * \param buf The destination buffer. |
| * \param blen The size of the destination buffer. |
| * \param f_rng The RNG function. |
| * \param p_rng The RNG context. |
| * |
| * \return \c 0 on success. |
| * \return An \c MBEDTLS_ERR_ECP_XXX error code on failure. |
| */ |
| 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 This function parses and processes a TLS ClientKeyExchange |
| * payload. |
| * |
| * This is the second function used by a TLS server for ECDH(E) |
| * ciphersuites. |
| * |
| * \see ecp.h |
| * |
| * \param ctx The ECDH context. |
| * \param buf The start of the input buffer. |
| * \param blen The length of the input buffer. |
| * |
| * \return \c 0 on success. |
| * \return An \c MBEDTLS_ERR_ECP_XXX error code on failure. |
| */ |
| int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx, |
| const unsigned char *buf, size_t blen ); |
| |
| /** |
| * \brief This function derives and exports the shared secret. |
| * |
| * This is the last function used by both TLS client |
| * and servers. |
| * |
| * \note If \p f_rng is not NULL, it is used to implement |
| * countermeasures against side-channel attacks. |
| * For more information, see mbedtls_ecp_mul(). |
| * |
| * \see ecp.h |
| * |
| * \param ctx The ECDH context. |
| * \param olen The number of Bytes written. |
| * \param buf The destination buffer. |
| * \param blen The length of the destination buffer. |
| * \param f_rng The RNG function. |
| * \param p_rng The RNG context. |
| * |
| * \return \c 0 on success. |
| * \return An \c MBEDTLS_ERR_ECP_XXX error code on failure. |
| */ |
| 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 */ |