278 lines
11 KiB
C
278 lines
11 KiB
C
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/**
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* \file ecjpake.h
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*
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* \brief Elliptic curve J-PAKE
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*/
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/*
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* Copyright (C) 2006-2015, ARM Limited, 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_ECJPAKE_H
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#define MBEDTLS_ECJPAKE_H
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/*
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* J-PAKE is a password-authenticated key exchange that allows deriving a
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* strong shared secret from a (potentially low entropy) pre-shared
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* passphrase, with forward secrecy and mutual authentication.
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* https://en.wikipedia.org/wiki/Password_Authenticated_Key_Exchange_by_Juggling
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*
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* This file implements the Elliptic Curve variant of J-PAKE,
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* as defined in Chapter 7.4 of the Thread v1.0 Specification,
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* available to members of the Thread Group http://threadgroup.org/
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*
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* As the J-PAKE algorithm is inherently symmetric, so is our API.
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* Each party needs to send its first round message, in any order, to the
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* other party, then each sends its second round message, in any order.
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* The payloads are serialized in a way suitable for use in TLS, but could
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* also be use outside TLS.
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*/
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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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#include "md.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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* Roles in the EC J-PAKE exchange
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*/
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typedef enum {
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MBEDTLS_ECJPAKE_CLIENT = 0, /**< Client */
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MBEDTLS_ECJPAKE_SERVER, /**< Server */
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} mbedtls_ecjpake_role;
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#if !defined(MBEDTLS_ECJPAKE_ALT)
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/**
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* EC J-PAKE context structure.
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*
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* J-PAKE is a symmetric protocol, except for the identifiers used in
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* Zero-Knowledge Proofs, and the serialization of the second message
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* (KeyExchange) as defined by the Thread spec.
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*
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* In order to benefit from this symmetry, we choose a different naming
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* convetion from the Thread v1.0 spec. Correspondance is indicated in the
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* description as a pair C: client name, S: server name
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*/
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typedef struct mbedtls_ecjpake_context
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{
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const mbedtls_md_info_t *md_info; /**< Hash to use */
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mbedtls_ecp_group grp; /**< Elliptic curve */
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mbedtls_ecjpake_role role; /**< Are we client or server? */
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int point_format; /**< Format for point export */
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mbedtls_ecp_point Xm1; /**< My public key 1 C: X1, S: X3 */
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mbedtls_ecp_point Xm2; /**< My public key 2 C: X2, S: X4 */
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mbedtls_ecp_point Xp1; /**< Peer public key 1 C: X3, S: X1 */
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mbedtls_ecp_point Xp2; /**< Peer public key 2 C: X4, S: X2 */
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mbedtls_ecp_point Xp; /**< Peer public key C: Xs, S: Xc */
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mbedtls_mpi xm1; /**< My private key 1 C: x1, S: x3 */
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mbedtls_mpi xm2; /**< My private key 2 C: x2, S: x4 */
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mbedtls_mpi s; /**< Pre-shared secret (passphrase) */
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} mbedtls_ecjpake_context;
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#else /* MBEDTLS_ECJPAKE_ALT */
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#include "ecjpake_alt.h"
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#endif /* MBEDTLS_ECJPAKE_ALT */
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/**
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* \brief Initialize an ECJPAKE context.
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*
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* \param ctx The ECJPAKE context to initialize.
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* This must not be \c NULL.
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*/
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void mbedtls_ecjpake_init( mbedtls_ecjpake_context *ctx );
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/**
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* \brief Set up an ECJPAKE context for use.
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*
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* \note Currently the only values for hash/curve allowed by the
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* standard are #MBEDTLS_MD_SHA256/#MBEDTLS_ECP_DP_SECP256R1.
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*
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* \param ctx The ECJPAKE context to set up. This must be initialized.
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* \param role The role of the caller. This must be either
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* #MBEDTLS_ECJPAKE_CLIENT or #MBEDTLS_ECJPAKE_SERVER.
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* \param hash The identifier of the hash function to use,
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* for example #MBEDTLS_MD_SHA256.
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* \param curve The identifier of the elliptic curve to use,
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* for example #MBEDTLS_ECP_DP_SECP256R1.
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* \param secret The pre-shared secret (passphrase). This must be
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* a readable buffer of length \p len Bytes. It need
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* only be valid for the duration of this call.
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* \param len The length of the pre-shared secret \p secret.
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*
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* \return \c 0 if successful.
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* \return A negative error code on failure.
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*/
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int mbedtls_ecjpake_setup( mbedtls_ecjpake_context *ctx,
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mbedtls_ecjpake_role role,
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mbedtls_md_type_t hash,
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mbedtls_ecp_group_id curve,
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const unsigned char *secret,
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size_t len );
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/**
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* \brief Check if an ECJPAKE context is ready for use.
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*
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* \param ctx The ECJPAKE context to check. This must be
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* initialized.
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*
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* \return \c 0 if the context is ready for use.
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* \return #MBEDTLS_ERR_ECP_BAD_INPUT_DATA otherwise.
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*/
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int mbedtls_ecjpake_check( const mbedtls_ecjpake_context *ctx );
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/**
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* \brief Generate and write the first round message
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* (TLS: contents of the Client/ServerHello extension,
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* excluding extension type and length bytes).
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*
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* \param ctx The ECJPAKE context to use. This must be
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* initialized and set up.
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* \param buf The buffer to write the contents to. This must be a
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* writable buffer of length \p len Bytes.
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* \param len The length of \p buf in Bytes.
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* \param olen The address at which to store the total number
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* of Bytes written to \p buf. This must not be \c NULL.
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* \param f_rng The RNG function to use. This must not be \c NULL.
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* \param p_rng The RNG parameter to be passed to \p f_rng. This
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* may be \c NULL if \p f_rng doesn't use a context.
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*
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* \return \c 0 if successful.
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* \return A negative error code on failure.
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*/
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int mbedtls_ecjpake_write_round_one( mbedtls_ecjpake_context *ctx,
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unsigned char *buf, size_t len, size_t *olen,
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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 Read and process the first round message
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* (TLS: contents of the Client/ServerHello extension,
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* excluding extension type and length bytes).
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*
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* \param ctx The ECJPAKE context to use. This must be initialized
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* and set up.
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* \param buf The buffer holding the first round message. This must
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* be a readable buffer of length \p len Bytes.
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* \param len The length in Bytes of \p buf.
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*
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* \return \c 0 if successful.
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* \return A negative error code on failure.
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*/
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int mbedtls_ecjpake_read_round_one( mbedtls_ecjpake_context *ctx,
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const unsigned char *buf,
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size_t len );
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/**
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* \brief Generate and write the second round message
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* (TLS: contents of the Client/ServerKeyExchange).
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*
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* \param ctx The ECJPAKE context to use. This must be initialized,
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* set up, and already have performed round one.
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* \param buf The buffer to write the round two contents to.
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* This must be a writable buffer of length \p len Bytes.
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* \param len The size of \p buf in Bytes.
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* \param olen The address at which to store the total number of Bytes
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* written to \p buf. This must not be \c NULL.
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* \param f_rng The RNG function to use. This must not be \c NULL.
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* \param p_rng The RNG parameter to be passed to \p f_rng. This
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* may be \c NULL if \p f_rng doesn't use a context.
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*
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* \return \c 0 if successful.
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* \return A negative error code on failure.
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*/
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int mbedtls_ecjpake_write_round_two( mbedtls_ecjpake_context *ctx,
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unsigned char *buf, size_t len, size_t *olen,
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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 Read and process the second round message
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* (TLS: contents of the Client/ServerKeyExchange).
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*
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* \param ctx The ECJPAKE context to use. This must be initialized
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* and set up and already have performed round one.
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* \param buf The buffer holding the second round message. This must
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* be a readable buffer of length \p len Bytes.
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* \param len The length in Bytes of \p buf.
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*
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* \return \c 0 if successful.
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* \return A negative error code on failure.
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*/
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int mbedtls_ecjpake_read_round_two( mbedtls_ecjpake_context *ctx,
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const unsigned char *buf,
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size_t len );
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/**
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* \brief Derive the shared secret
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* (TLS: Pre-Master Secret).
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*
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* \param ctx The ECJPAKE context to use. This must be initialized,
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* set up and have performed both round one and two.
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* \param buf The buffer to write the derived secret to. This must
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* be a writable buffer of length \p len Bytes.
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* \param len The length of \p buf in Bytes.
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* \param olen The address at which to store the total number of Bytes
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* written to \p buf. This must not be \c NULL.
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* \param f_rng The RNG function to use. This must not be \c NULL.
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* \param p_rng The RNG parameter to be passed to \p f_rng. This
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* may be \c NULL if \p f_rng doesn't use a context.
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*
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* \return \c 0 if successful.
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* \return A negative error code on failure.
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*/
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int mbedtls_ecjpake_derive_secret( mbedtls_ecjpake_context *ctx,
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unsigned char *buf, size_t len, size_t *olen,
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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 clears an ECJPAKE context and frees any
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* embedded data structure.
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*
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* \param ctx The ECJPAKE context to free. This may be \c NULL,
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* in which case this function does nothing. If it is not
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* \c NULL, it must point to an initialized ECJPAKE context.
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*/
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void mbedtls_ecjpake_free( mbedtls_ecjpake_context *ctx );
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#if defined(MBEDTLS_SELF_TEST)
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/**
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* \brief Checkup routine
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*
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* \return 0 if successful, or 1 if a test failed
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*/
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int mbedtls_ecjpake_self_test( int verbose );
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#endif /* MBEDTLS_SELF_TEST */
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#ifdef __cplusplus
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}
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#endif
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#endif /* ecjpake.h */
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