1 /** 2 * \file entropy.h 3 * 4 * \brief Entropy accumulator implementation 5 */ 6 /* 7 * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved 8 * SPDX-License-Identifier: GPL-2.0 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License as published by 12 * the Free Software Foundation; either version 2 of the License, or 13 * (at your option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, 16 * but WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 * GNU General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public License along 21 * with this program; if not, write to the Free Software Foundation, Inc., 22 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 23 * 24 * This file is part of mbed TLS (https://tls.mbed.org) 25 */ 26 #ifndef MBEDTLS_ENTROPY_H 27 #define MBEDTLS_ENTROPY_H 28 29 #if !defined(MBEDTLS_CONFIG_FILE) 30 #include "config.h" 31 #else 32 #include MBEDTLS_CONFIG_FILE 33 #endif 34 35 #include <stddef.h> 36 37 #if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256) 38 #include "sha512.h" 39 #define MBEDTLS_ENTROPY_SHA512_ACCUMULATOR 40 #else 41 #if defined(MBEDTLS_SHA256_C) 42 #define MBEDTLS_ENTROPY_SHA256_ACCUMULATOR 43 #include "sha256.h" 44 #endif 45 #endif 46 47 #if defined(MBEDTLS_THREADING_C) 48 #include "threading.h" 49 #endif 50 51 #if defined(MBEDTLS_HAVEGE_C) 52 #include "havege.h" 53 #endif 54 55 #define MBEDTLS_ERR_ENTROPY_SOURCE_FAILED -0x003C /**< Critical entropy source failure. */ 56 #define MBEDTLS_ERR_ENTROPY_MAX_SOURCES -0x003E /**< No more sources can be added. */ 57 #define MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED -0x0040 /**< No sources have been added to poll. */ 58 #define MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE -0x003D /**< No strong sources have been added to poll. */ 59 #define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR -0x003F /**< Read/write error in file. */ 60 61 /** 62 * \name SECTION: Module settings 63 * 64 * The configuration options you can set for this module are in this section. 65 * Either change them in config.h or define them on the compiler command line. 66 * \{ 67 */ 68 69 #if !defined(MBEDTLS_ENTROPY_MAX_SOURCES) 70 #define MBEDTLS_ENTROPY_MAX_SOURCES 20 /**< Maximum number of sources supported */ 71 #endif 72 73 #if !defined(MBEDTLS_ENTROPY_MAX_GATHER) 74 #define MBEDTLS_ENTROPY_MAX_GATHER 128 /**< Maximum amount requested from entropy sources */ 75 #endif 76 77 /* \} name SECTION: Module settings */ 78 79 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 80 #define MBEDTLS_ENTROPY_BLOCK_SIZE 64 /**< Block size of entropy accumulator (SHA-512) */ 81 #else 82 #define MBEDTLS_ENTROPY_BLOCK_SIZE 32 /**< Block size of entropy accumulator (SHA-256) */ 83 #endif 84 85 #define MBEDTLS_ENTROPY_MAX_SEED_SIZE 1024 /**< Maximum size of seed we read from seed file */ 86 #define MBEDTLS_ENTROPY_SOURCE_MANUAL MBEDTLS_ENTROPY_MAX_SOURCES 87 88 #define MBEDTLS_ENTROPY_SOURCE_STRONG 1 /**< Entropy source is strong */ 89 #define MBEDTLS_ENTROPY_SOURCE_WEAK 0 /**< Entropy source is weak */ 90 91 #ifdef __cplusplus 92 extern "C" { 93 #endif 94 95 /** 96 * \brief Entropy poll callback pointer 97 * 98 * \param data Callback-specific data pointer 99 * \param output Data to fill 100 * \param len Maximum size to provide 101 * \param olen The actual amount of bytes put into the buffer (Can be 0) 102 * 103 * \return 0 if no critical failures occurred, 104 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED otherwise 105 */ 106 typedef int (*mbedtls_entropy_f_source_ptr)(void *data, unsigned char *output, size_t len, 107 size_t *olen); 108 109 /** 110 * \brief Entropy source state 111 */ 112 typedef struct 113 { 114 mbedtls_entropy_f_source_ptr f_source; /**< The entropy source callback */ 115 void * p_source; /**< The callback data pointer */ 116 size_t size; /**< Amount received in bytes */ 117 size_t threshold; /**< Minimum bytes required before release */ 118 int strong; /**< Is the source strong? */ 119 } 120 mbedtls_entropy_source_state; 121 122 /** 123 * \brief Entropy context structure 124 */ 125 typedef struct 126 { 127 int accumulator_started; 128 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 129 mbedtls_sha512_context accumulator; 130 #else 131 mbedtls_sha256_context accumulator; 132 #endif 133 int source_count; 134 mbedtls_entropy_source_state source[MBEDTLS_ENTROPY_MAX_SOURCES]; 135 #if defined(MBEDTLS_HAVEGE_C) 136 mbedtls_havege_state havege_data; 137 #endif 138 #if defined(MBEDTLS_THREADING_C) 139 mbedtls_threading_mutex_t mutex; /*!< mutex */ 140 #endif 141 #if defined(MBEDTLS_ENTROPY_NV_SEED) 142 int initial_entropy_run; 143 #endif 144 } 145 mbedtls_entropy_context; 146 147 /** 148 * \brief Initialize the context 149 * 150 * \param ctx Entropy context to initialize 151 */ 152 void mbedtls_entropy_init( mbedtls_entropy_context *ctx ); 153 154 /** 155 * \brief Free the data in the context 156 * 157 * \param ctx Entropy context to free 158 */ 159 void mbedtls_entropy_free( mbedtls_entropy_context *ctx ); 160 161 /** 162 * \brief Adds an entropy source to poll 163 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 164 * 165 * \param ctx Entropy context 166 * \param f_source Entropy function 167 * \param p_source Function data 168 * \param threshold Minimum required from source before entropy is released 169 * ( with mbedtls_entropy_func() ) (in bytes) 170 * \param strong MBEDTLS_ENTROPY_SOURCE_STRONG or 171 * MBEDTSL_ENTROPY_SOURCE_WEAK. 172 * At least one strong source needs to be added. 173 * Weaker sources (such as the cycle counter) can be used as 174 * a complement. 175 * 176 * \return 0 if successful or MBEDTLS_ERR_ENTROPY_MAX_SOURCES 177 */ 178 int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx, 179 mbedtls_entropy_f_source_ptr f_source, void *p_source, 180 size_t threshold, int strong ); 181 182 /** 183 * \brief Trigger an extra gather poll for the accumulator 184 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 185 * 186 * \param ctx Entropy context 187 * 188 * \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 189 */ 190 int mbedtls_entropy_gather( mbedtls_entropy_context *ctx ); 191 192 /** 193 * \brief Retrieve entropy from the accumulator 194 * (Maximum length: MBEDTLS_ENTROPY_BLOCK_SIZE) 195 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 196 * 197 * \param data Entropy context 198 * \param output Buffer to fill 199 * \param len Number of bytes desired, must be at most MBEDTLS_ENTROPY_BLOCK_SIZE 200 * 201 * \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 202 */ 203 int mbedtls_entropy_func( void *data, unsigned char *output, size_t len ); 204 205 /** 206 * \brief Add data to the accumulator manually 207 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 208 * 209 * \param ctx Entropy context 210 * \param data Data to add 211 * \param len Length of data 212 * 213 * \return 0 if successful 214 */ 215 int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx, 216 const unsigned char *data, size_t len ); 217 218 #if defined(MBEDTLS_ENTROPY_NV_SEED) 219 /** 220 * \brief Trigger an update of the seed file in NV by using the 221 * current entropy pool. 222 * 223 * \param ctx Entropy context 224 * 225 * \return 0 if successful 226 */ 227 int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx ); 228 #endif /* MBEDTLS_ENTROPY_NV_SEED */ 229 230 #if defined(MBEDTLS_FS_IO) 231 /** 232 * \brief Write a seed file 233 * 234 * \param ctx Entropy context 235 * \param path Name of the file 236 * 237 * \return 0 if successful, 238 * MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, or 239 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 240 */ 241 int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path ); 242 243 /** 244 * \brief Read and update a seed file. Seed is added to this 245 * instance. No more than MBEDTLS_ENTROPY_MAX_SEED_SIZE bytes are 246 * read from the seed file. The rest is ignored. 247 * 248 * \param ctx Entropy context 249 * \param path Name of the file 250 * 251 * \return 0 if successful, 252 * MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, 253 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 254 */ 255 int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path ); 256 #endif /* MBEDTLS_FS_IO */ 257 258 #if defined(MBEDTLS_SELF_TEST) 259 /** 260 * \brief Checkup routine 261 * 262 * This module self-test also calls the entropy self-test, 263 * mbedtls_entropy_source_self_test(); 264 * 265 * \return 0 if successful, or 1 if a test failed 266 */ 267 int mbedtls_entropy_self_test( int verbose ); 268 269 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT) 270 /** 271 * \brief Checkup routine 272 * 273 * Verifies the integrity of the hardware entropy source 274 * provided by the function 'mbedtls_hardware_poll()'. 275 * 276 * Note this is the only hardware entropy source that is known 277 * at link time, and other entropy sources configured 278 * dynamically at runtime by the function 279 * mbedtls_entropy_add_source() will not be tested. 280 * 281 * \return 0 if successful, or 1 if a test failed 282 */ 283 int mbedtls_entropy_source_self_test( int verbose ); 284 #endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */ 285 #endif /* MBEDTLS_SELF_TEST */ 286 287 #ifdef __cplusplus 288 } 289 #endif 290 291 #endif /* entropy.h */ 292