mbedtls/include/mbedtls/ecjpake.h
2017-05-12 00:18:04 +01:00

238 lines
8.4 KiB
C

/**
* \file ecjpake.h
*
* \brief Elliptic curve J-PAKE
*
* 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_ECJPAKE_H
#define MBEDTLS_ECJPAKE_H
/*
* J-PAKE is a password-authenticated key exchange that allows deriving a
* strong shared secret from a (potentially low entropy) pre-shared
* passphrase, with forward secrecy and mutual authentication.
* https://en.wikipedia.org/wiki/Password_Authenticated_Key_Exchange_by_Juggling
*
* This file implements the Elliptic Curve variant of J-PAKE,
* as defined in Chapter 7.4 of the Thread v1.0 Specification,
* available to members of the Thread Group http://threadgroup.org/
*
* As the J-PAKE algorithm is inherently symmetric, so is our API.
* Each party needs to send its first round message, in any order, to the
* other party, then each sends its second round message, in any order.
* The payloads are serialized in a way suitable for use in TLS, but could
* also be use outside TLS.
*/
#include "ecp.h"
#include "md.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* Roles in the EC J-PAKE exchange
*/
typedef enum {
MBEDTLS_ECJPAKE_CLIENT = 0, /**< Client */
MBEDTLS_ECJPAKE_SERVER, /**< Server */
} mbedtls_ecjpake_role;
/**
* EC J-PAKE context structure.
*
* J-PAKE is a symmetric protocol, except for the identifiers used in
* Zero-Knowledge Proofs, and the serialization of the second message
* (KeyExchange) as defined by the Thread spec.
*
* In order to benefit from this symmetry, we choose a different naming
* convetion from the Thread v1.0 spec. Correspondance is indicated in the
* description as a pair C: client name, S: server name
*/
typedef struct
{
const mbedtls_md_info_t *md_info; /**< Hash to use */
mbedtls_ecp_group grp; /**< Elliptic curve */
mbedtls_ecjpake_role role; /**< Are we client or server? */
int point_format; /**< Format for point export */
mbedtls_ecp_point Xm1; /**< My public key 1 C: X1, S: X3 */
mbedtls_ecp_point Xm2; /**< My public key 2 C: X2, S: X4 */
mbedtls_ecp_point Xp1; /**< Peer public key 1 C: X3, S: X1 */
mbedtls_ecp_point Xp2; /**< Peer public key 2 C: X4, S: X2 */
mbedtls_ecp_point Xp; /**< Peer public key C: Xs, S: Xc */
mbedtls_mpi xm1; /**< My private key 1 C: x1, S: x3 */
mbedtls_mpi xm2; /**< My private key 2 C: x2, S: x4 */
mbedtls_mpi s; /**< Pre-shared secret (passphrase) */
} mbedtls_ecjpake_context;
/**
* \brief Initialize a context
* (just makes it ready for setup() or free()).
*
* \param ctx context to initialize
*/
void mbedtls_ecjpake_init( mbedtls_ecjpake_context *ctx );
/**
* \brief Set up a context for use
*
* \note Currently the only values for hash/curve allowed by the
* standard are MBEDTLS_MD_SHA256/MBEDTLS_ECP_DP_SECP256R1.
*
* \param ctx context to set up
* \param role Our role: client or server
* \param hash hash function to use (MBEDTLS_MD_XXX)
* \param curve elliptic curve identifier (MBEDTLS_ECP_DP_XXX)
* \param secret pre-shared secret (passphrase)
* \param len length of the shared secret
*
* \return 0 if successfull,
* a negative error code otherwise
*/
int mbedtls_ecjpake_setup( mbedtls_ecjpake_context *ctx,
mbedtls_ecjpake_role role,
mbedtls_md_type_t hash,
mbedtls_ecp_group_id curve,
const unsigned char *secret,
size_t len );
/**
* \brief Check if a context is ready for use
*
* \param ctx Context to check
*
* \return 0 if the context is ready for use,
* MBEDTLS_ERR_ECP_BAD_INPUT_DATA otherwise
*/
int mbedtls_ecjpake_check( const mbedtls_ecjpake_context *ctx );
/**
* \brief Generate and write the first round message
* (TLS: contents of the Client/ServerHello extension,
* excluding extension type and length bytes)
*
* \param ctx Context to use
* \param buf Buffer to write the contents to
* \param len Buffer size
* \param olen Will be updated with the number of bytes written
* \param f_rng RNG function
* \param p_rng RNG parameter
*
* \return 0 if successfull,
* a negative error code otherwise
*/
int mbedtls_ecjpake_write_round_one( mbedtls_ecjpake_context *ctx,
unsigned char *buf, size_t len, size_t *olen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \brief Read and process the first round message
* (TLS: contents of the Client/ServerHello extension,
* excluding extension type and length bytes)
*
* \param ctx Context to use
* \param buf Pointer to extension contents
* \param len Extension length
*
* \return 0 if successfull,
* a negative error code otherwise
*/
int mbedtls_ecjpake_read_round_one( mbedtls_ecjpake_context *ctx,
const unsigned char *buf,
size_t len );
/**
* \brief Generate and write the second round message
* (TLS: contents of the Client/ServerKeyExchange)
*
* \param ctx Context to use
* \param buf Buffer to write the contents to
* \param len Buffer size
* \param olen Will be updated with the number of bytes written
* \param f_rng RNG function
* \param p_rng RNG parameter
*
* \return 0 if successfull,
* a negative error code otherwise
*/
int mbedtls_ecjpake_write_round_two( mbedtls_ecjpake_context *ctx,
unsigned char *buf, size_t len, size_t *olen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \brief Read and process the second round message
* (TLS: contents of the Client/ServerKeyExchange)
*
* \param ctx Context to use
* \param buf Pointer to the message
* \param len Message length
*
* \return 0 if successfull,
* a negative error code otherwise
*/
int mbedtls_ecjpake_read_round_two( mbedtls_ecjpake_context *ctx,
const unsigned char *buf,
size_t len );
/**
* \brief Derive the shared secret
* (TLS: Pre-Master Secret)
*
* \param ctx Context to use
* \param buf Buffer to write the contents to
* \param len Buffer size
* \param olen Will be updated with the number of bytes written
* \param f_rng RNG function
* \param p_rng RNG parameter
*
* \return 0 if successfull,
* a negative error code otherwise
*/
int mbedtls_ecjpake_derive_secret( mbedtls_ecjpake_context *ctx,
unsigned char *buf, size_t len, size_t *olen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
/**
* \brief Free a context's content
*
* \param ctx context to free
*/
void mbedtls_ecjpake_free( mbedtls_ecjpake_context *ctx );
#if defined(MBEDTLS_SELF_TEST)
/**
* \brief Checkup routine
*
* \return 0 if successful, or 1 if a test failed
*/
int mbedtls_ecjpake_self_test( int verbose );
#endif
#ifdef __cplusplus
}
#endif
#endif /* ecjpake.h */