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 mbedtls_entropy_f_source_ptr MBEDTLS_PRIVATE(f_source); /**< The entropy source callback */ 109 void *MBEDTLS_PRIVATE(p_source); /**< The callback data pointer */ 110 size_t MBEDTLS_PRIVATE(size); /**< Amount received in bytes */ 111 size_t MBEDTLS_PRIVATE(threshold); /**< Minimum bytes required before release */ 112 int MBEDTLS_PRIVATE(strong); /**< Is the source strong? */ 113 } 114 mbedtls_entropy_source_state; 115 116 /** 117 * \brief Entropy context structure 118 */ 119 typedef struct mbedtls_entropy_context { 120 int MBEDTLS_PRIVATE(accumulator_started); /* 0 after init. 121 * 1 after the first update. 122 * -1 after free. */ 123 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 124 mbedtls_sha512_context MBEDTLS_PRIVATE(accumulator); 125 #elif defined(MBEDTLS_ENTROPY_SHA256_ACCUMULATOR) 126 mbedtls_sha256_context MBEDTLS_PRIVATE(accumulator); 127 #endif 128 int MBEDTLS_PRIVATE(source_count); /* Number of entries used in source. */ 129 mbedtls_entropy_source_state MBEDTLS_PRIVATE(source)[MBEDTLS_ENTROPY_MAX_SOURCES]; 130 #if defined(MBEDTLS_THREADING_C) 131 mbedtls_threading_mutex_t MBEDTLS_PRIVATE(mutex); /*!< mutex */ 132 #endif 133 #if defined(MBEDTLS_ENTROPY_NV_SEED) 134 int MBEDTLS_PRIVATE(initial_entropy_run); 135 #endif 136 } 137 mbedtls_entropy_context; 138 139 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY) 140 /** 141 * \brief Platform-specific entropy poll callback 142 */ 143 int mbedtls_platform_entropy_poll(void *data, 144 unsigned char *output, size_t len, size_t *olen); 145 #endif 146 147 /** 148 * \brief Initialize the context 149 * 150 * \param ctx Entropy context to initialize 151 */ 152 void mbedtls_entropy_init(mbedtls_entropy_context *ctx); 153 154 /** 155 * \brief Free the data in the context 156 * 157 * \param ctx Entropy context to free 158 */ 159 void mbedtls_entropy_free(mbedtls_entropy_context *ctx); 160 161 /** 162 * \brief Adds an entropy source to poll 163 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 164 * 165 * \param ctx Entropy context 166 * \param f_source Entropy function 167 * \param p_source Function data 168 * \param threshold Minimum required from source before entropy is released 169 * ( with mbedtls_entropy_func() ) (in bytes) 170 * \param strong MBEDTLS_ENTROPY_SOURCE_STRONG or 171 * MBEDTLS_ENTROPY_SOURCE_WEAK. 172 * At least one strong source needs to be added. 173 * Weaker sources (such as the cycle counter) can be used as 174 * a complement. 175 * 176 * \return 0 if successful or MBEDTLS_ERR_ENTROPY_MAX_SOURCES 177 */ 178 int mbedtls_entropy_add_source(mbedtls_entropy_context *ctx, 179 mbedtls_entropy_f_source_ptr f_source, void *p_source, 180 size_t threshold, int strong); 181 182 /** 183 * \brief Trigger an extra gather poll for the accumulator 184 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 185 * 186 * \param ctx Entropy context 187 * 188 * \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 189 */ 190 int mbedtls_entropy_gather(mbedtls_entropy_context *ctx); 191 192 /** 193 * \brief Retrieve entropy from the accumulator 194 * (Maximum length: MBEDTLS_ENTROPY_BLOCK_SIZE) 195 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 196 * 197 * \param data Entropy context 198 * \param output Buffer to fill 199 * \param len Number of bytes desired, must be at most MBEDTLS_ENTROPY_BLOCK_SIZE 200 * 201 * \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 202 */ 203 int mbedtls_entropy_func(void *data, unsigned char *output, size_t len); 204 205 /** 206 * \brief Add data to the accumulator manually 207 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 208 * 209 * \param ctx Entropy context 210 * \param data Data to add 211 * \param len Length of data 212 * 213 * \return 0 if successful 214 */ 215 int mbedtls_entropy_update_manual(mbedtls_entropy_context *ctx, 216 const unsigned char *data, size_t len); 217 218 #if defined(MBEDTLS_ENTROPY_NV_SEED) 219 /** 220 * \brief Trigger an update of the seed file in NV by using the 221 * current entropy pool. 222 * 223 * \param ctx Entropy context 224 * 225 * \return 0 if successful 226 */ 227 int mbedtls_entropy_update_nv_seed(mbedtls_entropy_context *ctx); 228 #endif /* MBEDTLS_ENTROPY_NV_SEED */ 229 230 #if defined(MBEDTLS_FS_IO) 231 /** 232 * \brief Write a seed file 233 * 234 * \param ctx Entropy context 235 * \param path Name of the file 236 * 237 * \return 0 if successful, 238 * MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, or 239 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 240 */ 241 int mbedtls_entropy_write_seed_file(mbedtls_entropy_context *ctx, const char *path); 242 243 /** 244 * \brief Read and update a seed file. Seed is added to this 245 * instance. No more than MBEDTLS_ENTROPY_MAX_SEED_SIZE bytes are 246 * read from the seed file. The rest is ignored. 247 * 248 * \param ctx Entropy context 249 * \param path Name of the file 250 * 251 * \return 0 if successful, 252 * MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, 253 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 254 */ 255 int mbedtls_entropy_update_seed_file(mbedtls_entropy_context *ctx, const char *path); 256 #endif /* MBEDTLS_FS_IO */ 257 258 #if defined(MBEDTLS_SELF_TEST) 259 /** 260 * \brief Checkup routine 261 * 262 * This module self-test also calls the entropy self-test, 263 * mbedtls_entropy_source_self_test(); 264 * 265 * \return 0 if successful, or 1 if a test failed 266 */ 267 int mbedtls_entropy_self_test(int verbose); 268 269 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT) 270 /** 271 * \brief Checkup routine 272 * 273 * Verifies the integrity of the hardware entropy source 274 * provided by the function 'mbedtls_hardware_poll()'. 275 * 276 * Note this is the only hardware entropy source that is known 277 * at link time, and other entropy sources configured 278 * dynamically at runtime by the function 279 * mbedtls_entropy_add_source() will not be tested. 280 * 281 * \return 0 if successful, or 1 if a test failed 282 */ 283 int mbedtls_entropy_source_self_test(int verbose); 284 #endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */ 285 #endif /* MBEDTLS_SELF_TEST */ 286 287 #ifdef __cplusplus 288 } 289 #endif 290 291 #endif /* entropy.h */ 292