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Diff: include/mbedtls/ecdh.h
- Revision:
- 0:cdf462088d13
diff -r 000000000000 -r cdf462088d13 include/mbedtls/ecdh.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/include/mbedtls/ecdh.h Thu Jan 05 00:18:44 2017 +0000 @@ -0,0 +1,214 @@ +/** + * \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 */