1 /** 2 * \file entropy.h 3 * 4 * \brief Entropy accumulator implementation 5 */ 6 /* 7 * Copyright The Mbed TLS Contributors 8 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 9 * 10 * This file is provided under the Apache License 2.0, or the 11 * GNU General Public License v2.0 or later. 12 * 13 * ********** 14 * Apache License 2.0: 15 * 16 * Licensed under the Apache License, Version 2.0 (the "License"); you may 17 * not use this file except in compliance with the License. 18 * You may obtain a copy of the License at 19 * 20 * http://www.apache.org/licenses/LICENSE-2.0 21 * 22 * Unless required by applicable law or agreed to in writing, software 23 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 25 * See the License for the specific language governing permissions and 26 * limitations under the License. 27 * 28 * ********** 29 * 30 * ********** 31 * GNU General Public License v2.0 or later: 32 * 33 * This program is free software; you can redistribute it and/or modify 34 * it under the terms of the GNU General Public License as published by 35 * the Free Software Foundation; either version 2 of the License, or 36 * (at your option) any later version. 37 * 38 * This program is distributed in the hope that it will be useful, 39 * but WITHOUT ANY WARRANTY; without even the implied warranty of 40 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 41 * GNU General Public License for more details. 42 * 43 * You should have received a copy of the GNU General Public License along 44 * with this program; if not, write to the Free Software Foundation, Inc., 45 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 46 * 47 * ********** 48 */ 49 #ifndef MBEDTLS_ENTROPY_H 50 #define MBEDTLS_ENTROPY_H 51 52 #if !defined(MBEDTLS_CONFIG_FILE) 53 #include "config.h" 54 #else 55 #include MBEDTLS_CONFIG_FILE 56 #endif 57 58 #include <stddef.h> 59 60 #if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256) 61 #include "sha512.h" 62 #define MBEDTLS_ENTROPY_SHA512_ACCUMULATOR 63 #else 64 #if defined(MBEDTLS_SHA256_C) 65 #define MBEDTLS_ENTROPY_SHA256_ACCUMULATOR 66 #include "sha256.h" 67 #endif 68 #endif 69 70 #if defined(MBEDTLS_THREADING_C) 71 #include "threading.h" 72 #endif 73 74 #if defined(MBEDTLS_HAVEGE_C) 75 #include "havege.h" 76 #endif 77 78 #define MBEDTLS_ERR_ENTROPY_SOURCE_FAILED -0x003C /**< Critical entropy source failure. */ 79 #define MBEDTLS_ERR_ENTROPY_MAX_SOURCES -0x003E /**< No more sources can be added. */ 80 #define MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED -0x0040 /**< No sources have been added to poll. */ 81 #define MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE -0x003D /**< No strong sources have been added to poll. */ 82 #define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR -0x003F /**< Read/write error in file. */ 83 84 /** 85 * \name SECTION: Module settings 86 * 87 * The configuration options you can set for this module are in this section. 88 * Either change them in config.h or define them on the compiler command line. 89 * \{ 90 */ 91 92 #if !defined(MBEDTLS_ENTROPY_MAX_SOURCES) 93 #define MBEDTLS_ENTROPY_MAX_SOURCES 20 /**< Maximum number of sources supported */ 94 #endif 95 96 #if !defined(MBEDTLS_ENTROPY_MAX_GATHER) 97 #define MBEDTLS_ENTROPY_MAX_GATHER 128 /**< Maximum amount requested from entropy sources */ 98 #endif 99 100 /* \} name SECTION: Module settings */ 101 102 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 103 #define MBEDTLS_ENTROPY_BLOCK_SIZE 64 /**< Block size of entropy accumulator (SHA-512) */ 104 #else 105 #define MBEDTLS_ENTROPY_BLOCK_SIZE 32 /**< Block size of entropy accumulator (SHA-256) */ 106 #endif 107 108 #define MBEDTLS_ENTROPY_MAX_SEED_SIZE 1024 /**< Maximum size of seed we read from seed file */ 109 #define MBEDTLS_ENTROPY_SOURCE_MANUAL MBEDTLS_ENTROPY_MAX_SOURCES 110 111 #define MBEDTLS_ENTROPY_SOURCE_STRONG 1 /**< Entropy source is strong */ 112 #define MBEDTLS_ENTROPY_SOURCE_WEAK 0 /**< Entropy source is weak */ 113 114 #ifdef __cplusplus 115 extern "C" { 116 #endif 117 118 /** 119 * \brief Entropy poll callback pointer 120 * 121 * \param data Callback-specific data pointer 122 * \param output Data to fill 123 * \param len Maximum size to provide 124 * \param olen The actual amount of bytes put into the buffer (Can be 0) 125 * 126 * \return 0 if no critical failures occurred, 127 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED otherwise 128 */ 129 typedef int (*mbedtls_entropy_f_source_ptr)(void *data, unsigned char *output, size_t len, 130 size_t *olen); 131 132 /** 133 * \brief Entropy source state 134 */ 135 typedef struct mbedtls_entropy_source_state 136 { 137 mbedtls_entropy_f_source_ptr f_source; /**< The entropy source callback */ 138 void * p_source; /**< The callback data pointer */ 139 size_t size; /**< Amount received in bytes */ 140 size_t threshold; /**< Minimum bytes required before release */ 141 int strong; /**< Is the source strong? */ 142 } 143 mbedtls_entropy_source_state; 144 145 /** 146 * \brief Entropy context structure 147 */ 148 typedef struct mbedtls_entropy_context 149 { 150 int accumulator_started; /* 0 after init. 151 * 1 after the first update. 152 * -1 after free. */ 153 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 154 mbedtls_sha512_context accumulator; 155 #else 156 mbedtls_sha256_context accumulator; 157 #endif 158 int source_count; /* Number of entries used in source. */ 159 mbedtls_entropy_source_state source[MBEDTLS_ENTROPY_MAX_SOURCES]; 160 #if defined(MBEDTLS_HAVEGE_C) 161 mbedtls_havege_state havege_data; 162 #endif 163 #if defined(MBEDTLS_THREADING_C) 164 mbedtls_threading_mutex_t mutex; /*!< mutex */ 165 #endif 166 #if defined(MBEDTLS_ENTROPY_NV_SEED) 167 int initial_entropy_run; 168 #endif 169 } 170 mbedtls_entropy_context; 171 172 /** 173 * \brief Initialize the context 174 * 175 * \param ctx Entropy context to initialize 176 */ 177 void mbedtls_entropy_init( mbedtls_entropy_context *ctx ); 178 179 /** 180 * \brief Free the data in the context 181 * 182 * \param ctx Entropy context to free 183 */ 184 void mbedtls_entropy_free( mbedtls_entropy_context *ctx ); 185 186 /** 187 * \brief Adds an entropy source to poll 188 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 189 * 190 * \param ctx Entropy context 191 * \param f_source Entropy function 192 * \param p_source Function data 193 * \param threshold Minimum required from source before entropy is released 194 * ( with mbedtls_entropy_func() ) (in bytes) 195 * \param strong MBEDTLS_ENTROPY_SOURCE_STRONG or 196 * MBEDTLS_ENTROPY_SOURCE_WEAK. 197 * At least one strong source needs to be added. 198 * Weaker sources (such as the cycle counter) can be used as 199 * a complement. 200 * 201 * \return 0 if successful or MBEDTLS_ERR_ENTROPY_MAX_SOURCES 202 */ 203 int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx, 204 mbedtls_entropy_f_source_ptr f_source, void *p_source, 205 size_t threshold, int strong ); 206 207 /** 208 * \brief Trigger an extra gather poll for the accumulator 209 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 210 * 211 * \param ctx Entropy context 212 * 213 * \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 214 */ 215 int mbedtls_entropy_gather( mbedtls_entropy_context *ctx ); 216 217 /** 218 * \brief Retrieve entropy from the accumulator 219 * (Maximum length: MBEDTLS_ENTROPY_BLOCK_SIZE) 220 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 221 * 222 * \param data Entropy context 223 * \param output Buffer to fill 224 * \param len Number of bytes desired, must be at most MBEDTLS_ENTROPY_BLOCK_SIZE 225 * 226 * \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 227 */ 228 int mbedtls_entropy_func( void *data, unsigned char *output, size_t len ); 229 230 /** 231 * \brief Add data to the accumulator manually 232 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 233 * 234 * \param ctx Entropy context 235 * \param data Data to add 236 * \param len Length of data 237 * 238 * \return 0 if successful 239 */ 240 int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx, 241 const unsigned char *data, size_t len ); 242 243 #if defined(MBEDTLS_ENTROPY_NV_SEED) 244 /** 245 * \brief Trigger an update of the seed file in NV by using the 246 * current entropy pool. 247 * 248 * \param ctx Entropy context 249 * 250 * \return 0 if successful 251 */ 252 int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx ); 253 #endif /* MBEDTLS_ENTROPY_NV_SEED */ 254 255 #if defined(MBEDTLS_FS_IO) 256 /** 257 * \brief Write a seed file 258 * 259 * \param ctx Entropy context 260 * \param path Name of the file 261 * 262 * \return 0 if successful, 263 * MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, or 264 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 265 */ 266 int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path ); 267 268 /** 269 * \brief Read and update a seed file. Seed is added to this 270 * instance. No more than MBEDTLS_ENTROPY_MAX_SEED_SIZE bytes are 271 * read from the seed file. The rest is ignored. 272 * 273 * \param ctx Entropy context 274 * \param path Name of the file 275 * 276 * \return 0 if successful, 277 * MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, 278 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 279 */ 280 int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path ); 281 #endif /* MBEDTLS_FS_IO */ 282 283 #if defined(MBEDTLS_SELF_TEST) 284 /** 285 * \brief Checkup routine 286 * 287 * This module self-test also calls the entropy self-test, 288 * mbedtls_entropy_source_self_test(); 289 * 290 * \return 0 if successful, or 1 if a test failed 291 */ 292 int mbedtls_entropy_self_test( int verbose ); 293 294 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT) 295 /** 296 * \brief Checkup routine 297 * 298 * Verifies the integrity of the hardware entropy source 299 * provided by the function 'mbedtls_hardware_poll()'. 300 * 301 * Note this is the only hardware entropy source that is known 302 * at link time, and other entropy sources configured 303 * dynamically at runtime by the function 304 * mbedtls_entropy_add_source() will not be tested. 305 * 306 * \return 0 if successful, or 1 if a test failed 307 */ 308 int mbedtls_entropy_source_self_test( int verbose ); 309 #endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */ 310 #endif /* MBEDTLS_SELF_TEST */ 311 312 #ifdef __cplusplus 313 } 314 #endif 315 316 #endif /* entropy.h */ 317