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