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 #ifndef MBEDTLS_ENTROPY_H 11 #define MBEDTLS_ENTROPY_H 12 #include "mbedtls/private_access.h" 13 14 #include "mbedtls/build_info.h" 15 16 #include <stddef.h> 17 18 #include "md.h" 19 20 #if (defined(MBEDTLS_MD_CAN_SHA512) || defined(PSA_WANT_ALG_SHA_512)) && \ 21 !defined(MBEDTLS_ENTROPY_FORCE_SHA256) 22 #define MBEDTLS_ENTROPY_SHA512_ACCUMULATOR 23 #define MBEDTLS_ENTROPY_MD MBEDTLS_MD_SHA512 24 #define MBEDTLS_ENTROPY_BLOCK_SIZE 64 /**< Block size of entropy accumulator (SHA-512) */ 25 #else 26 #if (defined(MBEDTLS_MD_CAN_SHA256) || defined(PSA_WANT_ALG_SHA_256)) 27 #define MBEDTLS_ENTROPY_SHA256_ACCUMULATOR 28 #define MBEDTLS_ENTROPY_MD MBEDTLS_MD_SHA256 29 #define MBEDTLS_ENTROPY_BLOCK_SIZE 32 /**< Block size of entropy accumulator (SHA-256) */ 30 #endif 31 #endif 32 33 #if defined(MBEDTLS_THREADING_C) 34 #include "mbedtls/threading.h" 35 #endif 36 37 38 /** Critical entropy source failure. */ 39 #define MBEDTLS_ERR_ENTROPY_SOURCE_FAILED -0x003C 40 /** No more sources can be added. */ 41 #define MBEDTLS_ERR_ENTROPY_MAX_SOURCES -0x003E 42 /** No sources have been added to poll. */ 43 #define MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED -0x0040 44 /** No strong sources have been added to poll. */ 45 #define MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE -0x003D 46 /** Read/write error in file. */ 47 #define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR -0x003F 48 49 /** 50 * \name SECTION: Module settings 51 * 52 * The configuration options you can set for this module are in this section. 53 * Either change them in mbedtls_config.h or define them on the compiler command line. 54 * \{ 55 */ 56 57 #if !defined(MBEDTLS_ENTROPY_MAX_SOURCES) 58 #define MBEDTLS_ENTROPY_MAX_SOURCES 20 /**< Maximum number of sources supported */ 59 #endif 60 61 #if !defined(MBEDTLS_ENTROPY_MAX_GATHER) 62 #define MBEDTLS_ENTROPY_MAX_GATHER 128 /**< Maximum amount requested from entropy sources */ 63 #endif 64 65 /** \} name SECTION: Module settings */ 66 67 #define MBEDTLS_ENTROPY_MAX_SEED_SIZE 1024 /**< Maximum size of seed we read from seed file */ 68 #define MBEDTLS_ENTROPY_SOURCE_MANUAL MBEDTLS_ENTROPY_MAX_SOURCES 69 70 #define MBEDTLS_ENTROPY_SOURCE_STRONG 1 /**< Entropy source is strong */ 71 #define MBEDTLS_ENTROPY_SOURCE_WEAK 0 /**< Entropy source is weak */ 72 73 #ifdef __cplusplus 74 extern "C" { 75 #endif 76 77 /** 78 * \brief Entropy poll callback pointer 79 * 80 * \param data Callback-specific data pointer 81 * \param output Data to fill 82 * \param len Maximum size to provide 83 * \param olen The actual amount of bytes put into the buffer (Can be 0) 84 * 85 * \return 0 if no critical failures occurred, 86 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED otherwise 87 */ 88 typedef int (*mbedtls_entropy_f_source_ptr)(void *data, unsigned char *output, size_t len, 89 size_t *olen); 90 91 /** 92 * \brief Entropy source state 93 */ 94 typedef struct mbedtls_entropy_source_state { 95 mbedtls_entropy_f_source_ptr MBEDTLS_PRIVATE(f_source); /**< The entropy source callback */ 96 void *MBEDTLS_PRIVATE(p_source); /**< The callback data pointer */ 97 size_t MBEDTLS_PRIVATE(size); /**< Amount received in bytes */ 98 size_t MBEDTLS_PRIVATE(threshold); /**< Minimum bytes required before release */ 99 int MBEDTLS_PRIVATE(strong); /**< Is the source strong? */ 100 } 101 mbedtls_entropy_source_state; 102 103 /** 104 * \brief Entropy context structure 105 */ 106 typedef struct mbedtls_entropy_context { 107 mbedtls_md_context_t MBEDTLS_PRIVATE(accumulator); 108 int MBEDTLS_PRIVATE(accumulator_started); /* 0 after init. 109 * 1 after the first update. 110 * -1 after free. */ 111 int MBEDTLS_PRIVATE(source_count); /* Number of entries used in source. */ 112 mbedtls_entropy_source_state MBEDTLS_PRIVATE(source)[MBEDTLS_ENTROPY_MAX_SOURCES]; 113 #if defined(MBEDTLS_THREADING_C) 114 mbedtls_threading_mutex_t MBEDTLS_PRIVATE(mutex); /*!< mutex */ 115 #endif 116 #if defined(MBEDTLS_ENTROPY_NV_SEED) 117 int MBEDTLS_PRIVATE(initial_entropy_run); 118 #endif 119 } 120 mbedtls_entropy_context; 121 122 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY) 123 /** 124 * \brief Platform-specific entropy poll callback 125 */ 126 int mbedtls_platform_entropy_poll(void *data, 127 unsigned char *output, size_t len, size_t *olen); 128 #endif 129 130 /** 131 * \brief Initialize the context 132 * 133 * \param ctx Entropy context to initialize 134 */ 135 void mbedtls_entropy_init(mbedtls_entropy_context *ctx); 136 137 /** 138 * \brief Free the data in the context 139 * 140 * \param ctx Entropy context to free 141 */ 142 void mbedtls_entropy_free(mbedtls_entropy_context *ctx); 143 144 /** 145 * \brief Adds an entropy source to poll 146 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 147 * 148 * \param ctx Entropy context 149 * \param f_source Entropy function 150 * \param p_source Function data 151 * \param threshold Minimum required from source before entropy is released 152 * ( with mbedtls_entropy_func() ) (in bytes) 153 * \param strong MBEDTLS_ENTROPY_SOURCE_STRONG or 154 * MBEDTLS_ENTROPY_SOURCE_WEAK. 155 * At least one strong source needs to be added. 156 * Weaker sources (such as the cycle counter) can be used as 157 * a complement. 158 * 159 * \return 0 if successful or MBEDTLS_ERR_ENTROPY_MAX_SOURCES 160 */ 161 int mbedtls_entropy_add_source(mbedtls_entropy_context *ctx, 162 mbedtls_entropy_f_source_ptr f_source, void *p_source, 163 size_t threshold, int strong); 164 165 /** 166 * \brief Trigger an extra gather poll for the accumulator 167 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 168 * 169 * \param ctx Entropy context 170 * 171 * \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 172 */ 173 int mbedtls_entropy_gather(mbedtls_entropy_context *ctx); 174 175 /** 176 * \brief Retrieve entropy from the accumulator 177 * (Maximum length: MBEDTLS_ENTROPY_BLOCK_SIZE) 178 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 179 * 180 * \param data Entropy context 181 * \param output Buffer to fill 182 * \param len Number of bytes desired, must be at most MBEDTLS_ENTROPY_BLOCK_SIZE 183 * 184 * \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 185 */ 186 int mbedtls_entropy_func(void *data, unsigned char *output, size_t len); 187 188 /** 189 * \brief Add data to the accumulator manually 190 * (Thread-safe if MBEDTLS_THREADING_C is enabled) 191 * 192 * \param ctx Entropy context 193 * \param data Data to add 194 * \param len Length of data 195 * 196 * \return 0 if successful 197 */ 198 int mbedtls_entropy_update_manual(mbedtls_entropy_context *ctx, 199 const unsigned char *data, size_t len); 200 201 #if defined(MBEDTLS_ENTROPY_NV_SEED) 202 /** 203 * \brief Trigger an update of the seed file in NV by using the 204 * current entropy pool. 205 * 206 * \param ctx Entropy context 207 * 208 * \return 0 if successful 209 */ 210 int mbedtls_entropy_update_nv_seed(mbedtls_entropy_context *ctx); 211 #endif /* MBEDTLS_ENTROPY_NV_SEED */ 212 213 #if defined(MBEDTLS_FS_IO) 214 /** 215 * \brief Write a seed file 216 * 217 * \param ctx Entropy context 218 * \param path Name of the file 219 * 220 * \return 0 if successful, 221 * MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, or 222 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 223 */ 224 int mbedtls_entropy_write_seed_file(mbedtls_entropy_context *ctx, const char *path); 225 226 /** 227 * \brief Read and update a seed file. Seed is added to this 228 * instance. No more than MBEDTLS_ENTROPY_MAX_SEED_SIZE bytes are 229 * read from the seed file. The rest is ignored. 230 * 231 * \param ctx Entropy context 232 * \param path Name of the file 233 * 234 * \return 0 if successful, 235 * MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, 236 * MBEDTLS_ERR_ENTROPY_SOURCE_FAILED 237 */ 238 int mbedtls_entropy_update_seed_file(mbedtls_entropy_context *ctx, const char *path); 239 #endif /* MBEDTLS_FS_IO */ 240 241 #if defined(MBEDTLS_SELF_TEST) 242 /** 243 * \brief Checkup routine 244 * 245 * This module self-test also calls the entropy self-test, 246 * mbedtls_entropy_source_self_test(); 247 * 248 * \return 0 if successful, or 1 if a test failed 249 */ 250 int mbedtls_entropy_self_test(int verbose); 251 252 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT) 253 /** 254 * \brief Checkup routine 255 * 256 * Verifies the integrity of the hardware entropy source 257 * provided by the function 'mbedtls_hardware_poll()'. 258 * 259 * Note this is the only hardware entropy source that is known 260 * at link time, and other entropy sources configured 261 * dynamically at runtime by the function 262 * mbedtls_entropy_add_source() will not be tested. 263 * 264 * \return 0 if successful, or 1 if a test failed 265 */ 266 int mbedtls_entropy_source_self_test(int verbose); 267 #endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */ 268 #endif /* MBEDTLS_SELF_TEST */ 269 270 #ifdef __cplusplus 271 } 272 #endif 273 274 #endif /* entropy.h */ 275