1 /** 2 * \file ecjpake.h 3 * 4 * \brief Elliptic curve J-PAKE 5 * 6 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 7 * SPDX-License-Identifier: Apache-2.0 8 * 9 * Licensed under the Apache License, Version 2.0 (the "License"); you may 10 * not use this file except in compliance with the License. 11 * You may obtain a copy of the License at 12 * 13 * http://www.apache.org/licenses/LICENSE-2.0 14 * 15 * Unless required by applicable law or agreed to in writing, software 16 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 17 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 18 * See the License for the specific language governing permissions and 19 * limitations under the License. 20 * 21 * This file is part of mbed TLS (https://tls.mbed.org) 22 */ 23 #ifndef MBEDTLS_ECJPAKE_H 24 #define MBEDTLS_ECJPAKE_H 25 26 /* 27 * J-PAKE is a password-authenticated key exchange that allows deriving a 28 * strong shared secret from a (potentially low entropy) pre-shared 29 * passphrase, with forward secrecy and mutual authentication. 30 * https://en.wikipedia.org/wiki/Password_Authenticated_Key_Exchange_by_Juggling 31 * 32 * This file implements the Elliptic Curve variant of J-PAKE, 33 * as defined in Chapter 7.4 of the Thread v1.0 Specification, 34 * available to members of the Thread Group http://threadgroup.org/ 35 * 36 * As the J-PAKE algorithm is inherently symmetric, so is our API. 37 * Each party needs to send its first round message, in any order, to the 38 * other party, then each sends its second round message, in any order. 39 * The payloads are serialized in a way suitable for use in TLS, but could 40 * also be use outside TLS. 41 */ 42 43 #include "ecp.h" 44 #include "md.h" 45 46 #ifdef __cplusplus 47 extern "C" { 48 #endif 49 50 /** 51 * Roles in the EC J-PAKE exchange 52 */ 53 typedef enum { 54 MBEDTLS_ECJPAKE_CLIENT = 0, /**< Client */ 55 MBEDTLS_ECJPAKE_SERVER, /**< Server */ 56 } mbedtls_ecjpake_role; 57 58 /** 59 * EC J-PAKE context structure. 60 * 61 * J-PAKE is a symmetric protocol, except for the identifiers used in 62 * Zero-Knowledge Proofs, and the serialization of the second message 63 * (KeyExchange) as defined by the Thread spec. 64 * 65 * In order to benefit from this symmetry, we choose a different naming 66 * convetion from the Thread v1.0 spec. Correspondance is indicated in the 67 * description as a pair C: client name, S: server name 68 */ 69 typedef struct 70 { 71 const mbedtls_md_info_t *md_info; /**< Hash to use */ 72 mbedtls_ecp_group grp; /**< Elliptic curve */ 73 mbedtls_ecjpake_role role; /**< Are we client or server? */ 74 int point_format; /**< Format for point export */ 75 76 mbedtls_ecp_point Xm1; /**< My public key 1 C: X1, S: X3 */ 77 mbedtls_ecp_point Xm2; /**< My public key 2 C: X2, S: X4 */ 78 mbedtls_ecp_point Xp1; /**< Peer public key 1 C: X3, S: X1 */ 79 mbedtls_ecp_point Xp2; /**< Peer public key 2 C: X4, S: X2 */ 80 mbedtls_ecp_point Xp; /**< Peer public key C: Xs, S: Xc */ 81 82 mbedtls_mpi xm1; /**< My private key 1 C: x1, S: x3 */ 83 mbedtls_mpi xm2; /**< My private key 2 C: x2, S: x4 */ 84 85 mbedtls_mpi s; /**< Pre-shared secret (passphrase) */ 86 } mbedtls_ecjpake_context; 87 88 /** 89 * \brief Initialize a context 90 * (just makes it ready for setup() or free()). 91 * 92 * \param ctx context to initialize 93 */ 94 void mbedtls_ecjpake_init( mbedtls_ecjpake_context *ctx ); 95 96 /** 97 * \brief Set up a context for use 98 * 99 * \note Currently the only values for hash/curve allowed by the 100 * standard are MBEDTLS_MD_SHA256/MBEDTLS_ECP_DP_SECP256R1. 101 * 102 * \param ctx context to set up 103 * \param role Our role: client or server 104 * \param hash hash function to use (MBEDTLS_MD_XXX) 105 * \param curve elliptic curve identifier (MBEDTLS_ECP_DP_XXX) 106 * \param secret pre-shared secret (passphrase) 107 * \param len length of the shared secret 108 * 109 * \return 0 if successfull, 110 * a negative error code otherwise 111 */ 112 int mbedtls_ecjpake_setup( mbedtls_ecjpake_context *ctx, 113 mbedtls_ecjpake_role role, 114 mbedtls_md_type_t hash, 115 mbedtls_ecp_group_id curve, 116 const unsigned char *secret, 117 size_t len ); 118 119 /* 120 * \brief Check if a context is ready for use 121 * 122 * \param ctx Context to check 123 * 124 * \return 0 if the context is ready for use, 125 * MBEDTLS_ERR_ECP_BAD_INPUT_DATA otherwise 126 */ 127 int mbedtls_ecjpake_check( const mbedtls_ecjpake_context *ctx ); 128 129 /** 130 * \brief Generate and write the first round message 131 * (TLS: contents of the Client/ServerHello extension, 132 * excluding extension type and length bytes) 133 * 134 * \param ctx Context to use 135 * \param buf Buffer to write the contents to 136 * \param len Buffer size 137 * \param olen Will be updated with the number of bytes written 138 * \param f_rng RNG function 139 * \param p_rng RNG parameter 140 * 141 * \return 0 if successfull, 142 * a negative error code otherwise 143 */ 144 int mbedtls_ecjpake_write_round_one( mbedtls_ecjpake_context *ctx, 145 unsigned char *buf, size_t len, size_t *olen, 146 int (*f_rng)(void *, unsigned char *, size_t), 147 void *p_rng ); 148 149 /** 150 * \brief Read and process the first round message 151 * (TLS: contents of the Client/ServerHello extension, 152 * excluding extension type and length bytes) 153 * 154 * \param ctx Context to use 155 * \param buf Pointer to extension contents 156 * \param len Extension length 157 * 158 * \return 0 if successfull, 159 * a negative error code otherwise 160 */ 161 int mbedtls_ecjpake_read_round_one( mbedtls_ecjpake_context *ctx, 162 const unsigned char *buf, 163 size_t len ); 164 165 /** 166 * \brief Generate and write the second round message 167 * (TLS: contents of the Client/ServerKeyExchange) 168 * 169 * \param ctx Context to use 170 * \param buf Buffer to write the contents to 171 * \param len Buffer size 172 * \param olen Will be updated with the number of bytes written 173 * \param f_rng RNG function 174 * \param p_rng RNG parameter 175 * 176 * \return 0 if successfull, 177 * a negative error code otherwise 178 */ 179 int mbedtls_ecjpake_write_round_two( mbedtls_ecjpake_context *ctx, 180 unsigned char *buf, size_t len, size_t *olen, 181 int (*f_rng)(void *, unsigned char *, size_t), 182 void *p_rng ); 183 184 /** 185 * \brief Read and process the second round message 186 * (TLS: contents of the Client/ServerKeyExchange) 187 * 188 * \param ctx Context to use 189 * \param buf Pointer to the message 190 * \param len Message length 191 * 192 * \return 0 if successfull, 193 * a negative error code otherwise 194 */ 195 int mbedtls_ecjpake_read_round_two( mbedtls_ecjpake_context *ctx, 196 const unsigned char *buf, 197 size_t len ); 198 199 /** 200 * \brief Derive the shared secret 201 * (TLS: Pre-Master Secret) 202 * 203 * \param ctx Context to use 204 * \param buf Buffer to write the contents to 205 * \param len Buffer size 206 * \param olen Will be updated with the number of bytes written 207 * \param f_rng RNG function 208 * \param p_rng RNG parameter 209 * 210 * \return 0 if successfull, 211 * a negative error code otherwise 212 */ 213 int mbedtls_ecjpake_derive_secret( mbedtls_ecjpake_context *ctx, 214 unsigned char *buf, size_t len, size_t *olen, 215 int (*f_rng)(void *, unsigned char *, size_t), 216 void *p_rng ); 217 218 /** 219 * \brief Free a context's content 220 * 221 * \param ctx context to free 222 */ 223 void mbedtls_ecjpake_free( mbedtls_ecjpake_context *ctx ); 224 225 #if defined(MBEDTLS_SELF_TEST) 226 /** 227 * \brief Checkup routine 228 * 229 * \return 0 if successful, or 1 if a test failed 230 */ 231 int mbedtls_ecjpake_self_test( int verbose ); 232 #endif 233 234 #ifdef __cplusplus 235 } 236 #endif 237 238 #endif /* ecjpake.h */ 239
