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