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 #include "mbedtls/private_access.h" 25 26 #include "mbedtls/build_info.h" 27 28 #include <stddef.h> 29 30 #if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256) 31 #include "mbedtls/sha512.h" 32 #define MBEDTLS_ENTROPY_SHA512_ACCUMULATOR 33 #else 34 #if defined(MBEDTLS_SHA256_C) 35 #define MBEDTLS_ENTROPY_SHA256_ACCUMULATOR 36 #include "mbedtls/sha256.h" 37 #endif 38 #endif 39 40 #if defined(MBEDTLS_THREADING_C) 41 #include "mbedtls/threading.h" 42 #endif 43 44 45 /** Critical entropy source failure. */ 46 #define MBEDTLS_ERR_ENTROPY_SOURCE_FAILED -0x003C 47 /** No more sources can be added. */ 48 #define MBEDTLS_ERR_ENTROPY_MAX_SOURCES -0x003E 49 /** No sources have been added to poll. */ 50 #define MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED -0x0040 51 /** No strong sources have been added to poll. */ 52 #define MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE -0x003D 53 /** Read/write error in file. */ 54 #define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR -0x003F 55 56 /** 57 * \name SECTION: Module settings 58 * 59 * The configuration options you can set for this module are in this section. 60 * Either change them in mbedtls_config.h or define them on the compiler command line. 61 * \{ 62 */ 63 64 #if !defined(MBEDTLS_ENTROPY_MAX_SOURCES) 65 #define MBEDTLS_ENTROPY_MAX_SOURCES 20 /**< Maximum number of sources supported */ 66 #endif 67 68 #if !defined(MBEDTLS_ENTROPY_MAX_GATHER) 69 #define MBEDTLS_ENTROPY_MAX_GATHER 128 /**< Maximum amount requested from entropy sources */ 70 #endif 71 72 /** \} name SECTION: Module settings */ 73 74 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 75 #define MBEDTLS_ENTROPY_BLOCK_SIZE 64 /**< Block size of entropy accumulator (SHA-512) */ 76 #else 77 #define MBEDTLS_ENTROPY_BLOCK_SIZE 32 /**< Block size of entropy accumulator (SHA-256) */ 78 #endif 79 80 #define MBEDTLS_ENTROPY_MAX_SEED_SIZE 1024 /**< Maximum size of seed we read from seed file */ 81 #define MBEDTLS_ENTROPY_SOURCE_MANUAL MBEDTLS_ENTROPY_MAX_SOURCES 82 83 #define MBEDTLS_ENTROPY_SOURCE_STRONG 1 /**< Entropy source is strong */ 84 #define MBEDTLS_ENTROPY_SOURCE_WEAK 0 /**< Entropy source is weak */ 85 86 #ifdef __cplusplus 87 extern "C" { 88 #endif 89 90 /** 91 * \brief Entropy poll callback pointer 92 * 93 * \param data Callback-specific data pointer 94 * \param output Data to fill 95 * \param len Maximum size to provide 96 * \param olen The actual amount of bytes put into the buffer (Can be 0) 97 * 98 * \return 0 if no critical failures occurred, 99 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED otherwise 100 */ 101 typedef int (*mbedtls_entropy_f_source_ptr)(void *data, unsigned char *output, size_t len, 102 size_t *olen); 103 104 /** 105 * \brief Entropy source state 106 */ 107 typedef struct mbedtls_entropy_source_state 108 { 109 mbedtls_entropy_f_source_ptr MBEDTLS_PRIVATE(f_source); /**< The entropy source callback */ 110 void * MBEDTLS_PRIVATE(p_source); /**< The callback data pointer */ 111 size_t MBEDTLS_PRIVATE(size); /**< Amount received in bytes */ 112 size_t MBEDTLS_PRIVATE(threshold); /**< Minimum bytes required before release */ 113 int MBEDTLS_PRIVATE(strong); /**< Is the source strong? */ 114 } 115 mbedtls_entropy_source_state; 116 117 /** 118 * \brief Entropy context structure 119 */ 120 typedef struct mbedtls_entropy_context 121 { 122 int MBEDTLS_PRIVATE(accumulator_started); /* 0 after init. 123 * 1 after the first update. 124 * -1 after free. */ 125 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 126 mbedtls_sha512_context MBEDTLS_PRIVATE(accumulator); 127 #elif defined(MBEDTLS_ENTROPY_SHA256_ACCUMULATOR) 128 mbedtls_sha256_context MBEDTLS_PRIVATE(accumulator); 129 #endif 130 int MBEDTLS_PRIVATE(source_count); /* Number of entries used in source. */ 131 mbedtls_entropy_source_state MBEDTLS_PRIVATE(source)[MBEDTLS_ENTROPY_MAX_SOURCES]; 132 #if defined(MBEDTLS_THREADING_C) 133 mbedtls_threading_mutex_t MBEDTLS_PRIVATE(mutex); /*!< mutex */ 134 #endif 135 #if defined(MBEDTLS_ENTROPY_NV_SEED) 136 int MBEDTLS_PRIVATE(initial_entropy_run); 137 #endif 138 } 139 mbedtls_entropy_context; 140 141 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY) 142 /** 143 * \brief Platform-specific entropy poll callback 144 */ 145 int mbedtls_platform_entropy_poll( void *data, 146 unsigned char *output, size_t len, size_t *olen ); 147 #endif 148 149 /** 150 * \brief Initialize the context 151 * 152 * \param ctx Entropy context to initialize 153 */ 154 void mbedtls_entropy_init( mbedtls_entropy_context *ctx ); 155 156 /** 157 * \brief Free the data in the context 158 * 159 * \param ctx Entropy context to free 160 */ 161 void mbedtls_entropy_free( mbedtls_entropy_context *ctx ); 162 163 /** 164 * \brief Adds an entropy source to poll 165 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 166 * 167 * \param ctx Entropy context 168 * \param f_source Entropy function 169 * \param p_source Function data 170 * \param threshold Minimum required from source before entropy is released 171 * ( with mbedtls_entropy_func() ) (in bytes) 172 * \param strong MBEDTLS_ENTROPY_SOURCE_STRONG or 173 * MBEDTLS_ENTROPY_SOURCE_WEAK. 174 * At least one strong source needs to be added. 175 * Weaker sources (such as the cycle counter) can be used as 176 * a complement. 177 * 178 * \return 0 if successful or MBEDTLS_ERR_ENTROPY_MAX_SOURCES 179 */ 180 int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx, 181 mbedtls_entropy_f_source_ptr f_source, void *p_source, 182 size_t threshold, int strong ); 183 184 /** 185 * \brief Trigger an extra gather poll for the accumulator 186 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 187 * 188 * \param ctx Entropy context 189 * 190 * \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 191 */ 192 int mbedtls_entropy_gather( mbedtls_entropy_context *ctx ); 193 194 /** 195 * \brief Retrieve entropy from the accumulator 196 * (Maximum length: MBEDTLS_ENTROPY_BLOCK_SIZE) 197 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 198 * 199 * \param data Entropy context 200 * \param output Buffer to fill 201 * \param len Number of bytes desired, must be at most MBEDTLS_ENTROPY_BLOCK_SIZE 202 * 203 * \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 204 */ 205 int mbedtls_entropy_func( void *data, unsigned char *output, size_t len ); 206 207 /** 208 * \brief Add data to the accumulator manually 209 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 210 * 211 * \param ctx Entropy context 212 * \param data Data to add 213 * \param len Length of data 214 * 215 * \return 0 if successful 216 */ 217 int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx, 218 const unsigned char *data, size_t len ); 219 220 #if defined(MBEDTLS_ENTROPY_NV_SEED) 221 /** 222 * \brief Trigger an update of the seed file in NV by using the 223 * current entropy pool. 224 * 225 * \param ctx Entropy context 226 * 227 * \return 0 if successful 228 */ 229 int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx ); 230 #endif /* MBEDTLS_ENTROPY_NV_SEED */ 231 232 #if defined(MBEDTLS_FS_IO) 233 /** 234 * \brief Write a seed file 235 * 236 * \param ctx Entropy context 237 * \param path Name of the file 238 * 239 * \return 0 if successful, 240 * MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, or 241 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 242 */ 243 int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path ); 244 245 /** 246 * \brief Read and update a seed file. Seed is added to this 247 * instance. No more than MBEDTLS_ENTROPY_MAX_SEED_SIZE bytes are 248 * read from the seed file. The rest is ignored. 249 * 250 * \param ctx Entropy context 251 * \param path Name of the file 252 * 253 * \return 0 if successful, 254 * MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, 255 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 256 */ 257 int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path ); 258 #endif /* MBEDTLS_FS_IO */ 259 260 #if defined(MBEDTLS_SELF_TEST) 261 /** 262 * \brief Checkup routine 263 * 264 * This module self-test also calls the entropy self-test, 265 * mbedtls_entropy_source_self_test(); 266 * 267 * \return 0 if successful, or 1 if a test failed 268 */ 269 int mbedtls_entropy_self_test( int verbose ); 270 271 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT) 272 /** 273 * \brief Checkup routine 274 * 275 * Verifies the integrity of the hardware entropy source 276 * provided by the function 'mbedtls_hardware_poll()'. 277 * 278 * Note this is the only hardware entropy source that is known 279 * at link time, and other entropy sources configured 280 * dynamically at runtime by the function 281 * mbedtls_entropy_add_source() will not be tested. 282 * 283 * \return 0 if successful, or 1 if a test failed 284 */ 285 int mbedtls_entropy_source_self_test( int verbose ); 286 #endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */ 287 #endif /* MBEDTLS_SELF_TEST */ 288 289 #ifdef __cplusplus 290 } 291 #endif 292 293 #endif /* entropy.h */ 294
