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 #define MBEDTLS_ERR_ENTROPY_SOURCE_FAILED -0x003C /**< Critical entropy source failure. */ 52 #define MBEDTLS_ERR_ENTROPY_MAX_SOURCES -0x003E /**< No more sources can be added. */ 53 #define MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED -0x0040 /**< No sources have been added to poll. */ 54 #define MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE -0x003D /**< No strong sources have been added to poll. */ 55 #define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR -0x003F /**< Read/write error in file. */ 56 57 /** 58 * \name SECTION: Module settings 59 * 60 * The configuration options you can set for this module are in this section. 61 * Either change them in config.h or define them on the compiler command line. 62 * \{ 63 */ 64 65 #if !defined(MBEDTLS_ENTROPY_MAX_SOURCES) 66 #define MBEDTLS_ENTROPY_MAX_SOURCES 20 /**< Maximum number of sources supported */ 67 #endif 68 69 #if !defined(MBEDTLS_ENTROPY_MAX_GATHER) 70 #define MBEDTLS_ENTROPY_MAX_GATHER 128 /**< Maximum amount requested from entropy sources */ 71 #endif 72 73 /* \} name SECTION: Module settings */ 74 75 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 76 #define MBEDTLS_ENTROPY_BLOCK_SIZE 64 /**< Block size of entropy accumulator (SHA-512) */ 77 #else 78 #define MBEDTLS_ENTROPY_BLOCK_SIZE 32 /**< Block size of entropy accumulator (SHA-256) */ 79 #endif 80 81 #define MBEDTLS_ENTROPY_MAX_SEED_SIZE 1024 /**< Maximum size of seed we read from seed file */ 82 #define MBEDTLS_ENTROPY_SOURCE_MANUAL MBEDTLS_ENTROPY_MAX_SOURCES 83 84 #define MBEDTLS_ENTROPY_SOURCE_STRONG 1 /**< Entropy source is strong */ 85 #define MBEDTLS_ENTROPY_SOURCE_WEAK 0 /**< Entropy source is weak */ 86 87 #ifdef __cplusplus 88 extern "C" { 89 #endif 90 91 /** 92 * \brief Entropy poll callback pointer 93 * 94 * \param data Callback-specific data pointer 95 * \param output Data to fill 96 * \param len Maximum size to provide 97 * \param olen The actual amount of bytes put into the buffer (Can be 0) 98 * 99 * \return 0 if no critical failures occurred, 100 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED otherwise 101 */ 102 typedef int (*mbedtls_entropy_f_source_ptr)(void *data, unsigned char *output, size_t len, 103 size_t *olen); 104 105 /** 106 * \brief Entropy source state 107 */ 108 typedef struct mbedtls_entropy_source_state 109 { 110 mbedtls_entropy_f_source_ptr f_source; /**< The entropy source callback */ 111 void * p_source; /**< The callback data pointer */ 112 size_t size; /**< Amount received in bytes */ 113 size_t threshold; /**< Minimum bytes required before release */ 114 int strong; /**< Is the source strong? */ 115 } 116 mbedtls_entropy_source_state; 117 118 /** 119 * \brief Entropy context structure 120 */ 121 typedef struct mbedtls_entropy_context 122 { 123 int accumulator_started; /* 0 after init. 124 * 1 after the first update. 125 * -1 after free. */ 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; /* Number of entries used in source. */ 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 * MBEDTLS_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