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File indexing completed on 2026-05-10 08:44:50
0001 /** 0002 * \file hmac_drbg.h 0003 * 0004 * \brief The HMAC_DRBG pseudorandom generator. 0005 * 0006 * This module implements the HMAC_DRBG pseudorandom generator described 0007 * in <em>NIST SP 800-90A: Recommendation for Random Number Generation Using 0008 * Deterministic Random Bit Generators</em>. 0009 */ 0010 /* 0011 * Copyright The Mbed TLS Contributors 0012 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 0013 */ 0014 #ifndef MBEDTLS_HMAC_DRBG_H 0015 #define MBEDTLS_HMAC_DRBG_H 0016 #include "mbedtls/private_access.h" 0017 0018 #include "tf-psa-crypto/build_info.h" 0019 0020 #include "mbedtls/md.h" 0021 0022 #if defined(MBEDTLS_THREADING_C) 0023 #include "mbedtls/threading.h" 0024 #endif 0025 0026 /* 0027 * Error codes 0028 */ 0029 /** Too many random requested in single call. */ 0030 #define MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG -0x0003 0031 /** Input too large (Entropy + additional). */ 0032 #define MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG -0x0005 0033 /** Read/write error in file. */ 0034 #define MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR -0x0007 0035 /** The entropy source failed. */ 0036 #define MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED -0x0009 0037 0038 /** 0039 * \name SECTION: Module settings 0040 * 0041 * The configuration options you can set for this module are in this section. 0042 * Either change them in mbedtls_config.h or define them on the compiler command line. 0043 * \{ 0044 */ 0045 0046 #if !defined(MBEDTLS_PSA_RNG_RESEED_INTERVAL) 0047 #define MBEDTLS_PSA_RNG_RESEED_INTERVAL 10000 /**< Interval before reseed is performed by default */ 0048 #endif 0049 0050 #define MBEDTLS_HMAC_DRBG_MAX_INPUT 256 /**< Maximum number of additional input bytes */ 0051 #define MBEDTLS_HMAC_DRBG_MAX_REQUEST 1024 /**< Maximum number of requested bytes per call */ 0052 #define MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT 384 /**< Maximum size of (re)seed buffer */ 0053 0054 /** \} name SECTION: Module settings */ 0055 0056 #define MBEDTLS_HMAC_DRBG_PR_OFF 0 /**< No prediction resistance */ 0057 #define MBEDTLS_HMAC_DRBG_PR_ON 1 /**< Prediction resistance enabled */ 0058 0059 #ifdef __cplusplus 0060 extern "C" { 0061 #endif 0062 0063 /** 0064 * HMAC_DRBG context. 0065 */ 0066 typedef struct mbedtls_hmac_drbg_context { 0067 /* Working state: the key K is not stored explicitly, 0068 * but is implied by the HMAC context */ 0069 mbedtls_md_context_t MBEDTLS_PRIVATE(md_ctx); /*!< HMAC context (inc. K) */ 0070 unsigned char MBEDTLS_PRIVATE(V)[MBEDTLS_MD_MAX_SIZE]; /*!< V in the spec */ 0071 int MBEDTLS_PRIVATE(reseed_counter); /*!< reseed counter */ 0072 0073 /* Administrative state */ 0074 size_t MBEDTLS_PRIVATE(entropy_len); /*!< entropy bytes grabbed on each (re)seed */ 0075 int MBEDTLS_PRIVATE(prediction_resistance); /*!< enable prediction resistance (Automatic 0076 reseed before every random generation) */ 0077 int MBEDTLS_PRIVATE(reseed_interval); /*!< reseed interval */ 0078 0079 /* Callbacks */ 0080 int(*MBEDTLS_PRIVATE(f_entropy))(void *, unsigned char *, size_t); /*!< entropy function */ 0081 void *MBEDTLS_PRIVATE(p_entropy); /*!< context for the entropy function */ 0082 0083 #if defined(MBEDTLS_THREADING_C) 0084 /* Invariant: the mutex is initialized if and only if 0085 * md_ctx->md_info != NULL. This means that the mutex is initialized 0086 * during the initial seeding in mbedtls_hmac_drbg_seed() or 0087 * mbedtls_hmac_drbg_seed_buf() and freed in mbedtls_ctr_drbg_free(). 0088 * 0089 * Note that this invariant may change without notice. Do not rely on it 0090 * and do not access the mutex directly in application code. 0091 */ 0092 mbedtls_threading_mutex_t MBEDTLS_PRIVATE(mutex); 0093 #endif 0094 } mbedtls_hmac_drbg_context; 0095 0096 /** 0097 * \brief HMAC_DRBG context initialization. 0098 * 0099 * This function makes the context ready for mbedtls_hmac_drbg_seed(), 0100 * mbedtls_hmac_drbg_seed_buf() or mbedtls_hmac_drbg_free(). 0101 * 0102 * \note The reseed interval is #MBEDTLS_PSA_RNG_RESEED_INTERVAL 0103 * by default. Override this value by calling 0104 * mbedtls_hmac_drbg_set_reseed_interval(). 0105 * 0106 * \param ctx HMAC_DRBG context to be initialized. 0107 */ 0108 void mbedtls_hmac_drbg_init(mbedtls_hmac_drbg_context *ctx); 0109 0110 /** 0111 * \brief HMAC_DRBG initial seeding. 0112 * 0113 * Set the initial seed and set up the entropy source for future reseeds. 0114 * 0115 * A typical choice for the \p f_entropy and \p p_entropy parameters is 0116 * to use the entropy module: 0117 * - \p f_entropy is mbedtls_entropy_func(); 0118 * - \p p_entropy is an instance of ::mbedtls_entropy_context initialized 0119 * with mbedtls_entropy_init() (which registers the platform's default 0120 * entropy sources). 0121 * 0122 * You can provide a personalization string in addition to the 0123 * entropy source, to make this instantiation as unique as possible. 0124 * 0125 * \note By default, the security strength as defined by NIST is: 0126 * - 128 bits if \p md_info is SHA-1; 0127 * - 192 bits if \p md_info is SHA-224; 0128 * - 256 bits if \p md_info is SHA-256, SHA-384 or SHA-512. 0129 * Note that SHA-256 is just as efficient as SHA-224. 0130 * The security strength can be reduced if a smaller 0131 * entropy length is set with 0132 * mbedtls_hmac_drbg_set_entropy_len(). 0133 * 0134 * \note The default entropy length is the security strength 0135 * (converted from bits to bytes). You can override 0136 * it by calling mbedtls_hmac_drbg_set_entropy_len(). 0137 * 0138 * \note During the initial seeding, this function calls 0139 * the entropy source to obtain a nonce 0140 * whose length is half the entropy length. 0141 */ 0142 #if defined(MBEDTLS_THREADING_C) 0143 /** 0144 * \note When Mbed TLS is built with threading support, 0145 * after this function returns successfully, 0146 * it is safe to call mbedtls_hmac_drbg_random() 0147 * from multiple threads. Other operations, including 0148 * reseeding, are not thread-safe. 0149 */ 0150 #endif /* MBEDTLS_THREADING_C */ 0151 /** 0152 * \param ctx HMAC_DRBG context to be seeded. 0153 * \param md_info MD algorithm to use for HMAC_DRBG. 0154 * \param f_entropy The entropy callback, taking as arguments the 0155 * \p p_entropy context, the buffer to fill, and the 0156 * length of the buffer. 0157 * \p f_entropy is always called with a length that is 0158 * less than or equal to the entropy length. 0159 * \param p_entropy The entropy context to pass to \p f_entropy. 0160 * \param custom The personalization string. 0161 * This can be \c NULL, in which case the personalization 0162 * string is empty regardless of the value of \p len. 0163 * \param len The length of the personalization string. 0164 * This must be at most #MBEDTLS_HMAC_DRBG_MAX_INPUT 0165 * and also at most 0166 * #MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT - \c entropy_len * 3 / 2 0167 * where \c entropy_len is the entropy length 0168 * described above. 0169 * 0170 * \return \c 0 if successful. 0171 * \return #MBEDTLS_ERR_MD_BAD_INPUT_DATA if \p md_info is 0172 * invalid. 0173 * \return #MBEDTLS_ERR_MD_ALLOC_FAILED if there was not enough 0174 * memory to allocate context data. 0175 * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED 0176 * if the call to \p f_entropy failed. 0177 */ 0178 int mbedtls_hmac_drbg_seed(mbedtls_hmac_drbg_context *ctx, 0179 const mbedtls_md_info_t *md_info, 0180 int (*f_entropy)(void *, unsigned char *, size_t), 0181 void *p_entropy, 0182 const unsigned char *custom, 0183 size_t len); 0184 0185 /** 0186 * \brief Initialisation of simplified HMAC_DRBG (never reseeds). 0187 * 0188 * This function is meant for use in algorithms that need a pseudorandom 0189 * input such as deterministic ECDSA. 0190 */ 0191 #if defined(MBEDTLS_THREADING_C) 0192 /** 0193 * \note When Mbed TLS is built with threading support, 0194 * after this function returns successfully, 0195 * it is safe to call mbedtls_hmac_drbg_random() 0196 * from multiple threads. Other operations, including 0197 * reseeding, are not thread-safe. 0198 */ 0199 #endif /* MBEDTLS_THREADING_C */ 0200 /** 0201 * \param ctx HMAC_DRBG context to be initialised. 0202 * \param md_info MD algorithm to use for HMAC_DRBG. 0203 * \param data Concatenation of the initial entropy string and 0204 * the additional data. 0205 * \param data_len Length of \p data in bytes. 0206 * 0207 * \return \c 0 if successful. or 0208 * \return #MBEDTLS_ERR_MD_BAD_INPUT_DATA if \p md_info is 0209 * invalid. 0210 * \return #MBEDTLS_ERR_MD_ALLOC_FAILED if there was not enough 0211 * memory to allocate context data. 0212 */ 0213 int mbedtls_hmac_drbg_seed_buf(mbedtls_hmac_drbg_context *ctx, 0214 const mbedtls_md_info_t *md_info, 0215 const unsigned char *data, size_t data_len); 0216 0217 /** 0218 * \brief This function turns prediction resistance on or off. 0219 * The default value is off. 0220 * 0221 * \note If enabled, entropy is gathered at the beginning of 0222 * every call to mbedtls_hmac_drbg_random_with_add() 0223 * or mbedtls_hmac_drbg_random(). 0224 * Only use this if your entropy source has sufficient 0225 * throughput. 0226 * 0227 * \param ctx The HMAC_DRBG context. 0228 * \param resistance #MBEDTLS_HMAC_DRBG_PR_ON or #MBEDTLS_HMAC_DRBG_PR_OFF. 0229 */ 0230 void mbedtls_hmac_drbg_set_prediction_resistance(mbedtls_hmac_drbg_context *ctx, 0231 int resistance); 0232 0233 /** 0234 * \brief This function sets the amount of entropy grabbed on each 0235 * seed or reseed. 0236 * 0237 * See the documentation of mbedtls_hmac_drbg_seed() for the default value. 0238 * 0239 * \param ctx The HMAC_DRBG context. 0240 * \param len The amount of entropy to grab, in bytes. 0241 */ 0242 void mbedtls_hmac_drbg_set_entropy_len(mbedtls_hmac_drbg_context *ctx, 0243 size_t len); 0244 0245 /** 0246 * \brief Set the reseed interval. 0247 * 0248 * The reseed interval is the number of calls to mbedtls_hmac_drbg_random() 0249 * or mbedtls_hmac_drbg_random_with_add() after which the entropy function 0250 * is called again. 0251 * 0252 * The default value is #MBEDTLS_PSA_RNG_RESEED_INTERVAL. 0253 * 0254 * \param ctx The HMAC_DRBG context. 0255 * \param interval The reseed interval. 0256 */ 0257 void mbedtls_hmac_drbg_set_reseed_interval(mbedtls_hmac_drbg_context *ctx, 0258 int interval); 0259 0260 /** 0261 * \brief This function updates the state of the HMAC_DRBG context. 0262 * 0263 * \note This function is not thread-safe. It is not safe 0264 * to call this function if another thread might be 0265 * concurrently obtaining random numbers from the same 0266 * context or updating or reseeding the same context. 0267 * 0268 * \param ctx The HMAC_DRBG context. 0269 * \param additional The data to update the state with. 0270 * If this is \c NULL, there is no additional data. 0271 * \param add_len Length of \p additional in bytes. 0272 * Unused if \p additional is \c NULL. 0273 * 0274 * \return \c 0 on success, or an error from the underlying 0275 * hash calculation. 0276 */ 0277 int mbedtls_hmac_drbg_update(mbedtls_hmac_drbg_context *ctx, 0278 const unsigned char *additional, size_t add_len); 0279 0280 /** 0281 * \brief This function reseeds the HMAC_DRBG context, that is 0282 * extracts data from the entropy source. 0283 * 0284 * \note This function is not thread-safe. It is not safe 0285 * to call this function if another thread might be 0286 * concurrently obtaining random numbers from the same 0287 * context or updating or reseeding the same context. 0288 * 0289 * \param ctx The HMAC_DRBG context. 0290 * \param additional Additional data to add to the state. 0291 * If this is \c NULL, there is no additional data 0292 * and \p len should be \c 0. 0293 * \param len The length of the additional data. 0294 * This must be at most #MBEDTLS_HMAC_DRBG_MAX_INPUT 0295 * and also at most 0296 * #MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT - \c entropy_len 0297 * where \c entropy_len is the entropy length 0298 * (see mbedtls_hmac_drbg_set_entropy_len()). 0299 * 0300 * \return \c 0 if successful. 0301 * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED 0302 * if a call to the entropy function failed. 0303 */ 0304 int mbedtls_hmac_drbg_reseed(mbedtls_hmac_drbg_context *ctx, 0305 const unsigned char *additional, size_t len); 0306 0307 /** 0308 * \brief This function updates an HMAC_DRBG instance with additional 0309 * data and uses it to generate random data. 0310 * 0311 * This function automatically reseeds if the reseed counter is exceeded 0312 * or prediction resistance is enabled. 0313 * 0314 * \note This function is not thread-safe. It is not safe 0315 * to call this function if another thread might be 0316 * concurrently obtaining random numbers from the same 0317 * context or updating or reseeding the same context. 0318 * 0319 * \param p_rng The HMAC_DRBG context. This must be a pointer to a 0320 * #mbedtls_hmac_drbg_context structure. 0321 * \param output The buffer to fill. 0322 * \param output_len The length of the buffer in bytes. 0323 * This must be at most #MBEDTLS_HMAC_DRBG_MAX_REQUEST. 0324 * \param additional Additional data to update with. 0325 * If this is \c NULL, there is no additional data 0326 * and \p add_len should be \c 0. 0327 * \param add_len The length of the additional data. 0328 * This must be at most #MBEDTLS_HMAC_DRBG_MAX_INPUT. 0329 * 0330 * \return \c 0 if successful. 0331 * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED 0332 * if a call to the entropy source failed. 0333 * \return #MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG if 0334 * \p output_len > #MBEDTLS_HMAC_DRBG_MAX_REQUEST. 0335 * \return #MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG if 0336 * \p add_len > #MBEDTLS_HMAC_DRBG_MAX_INPUT. 0337 */ 0338 int mbedtls_hmac_drbg_random_with_add(void *p_rng, 0339 unsigned char *output, size_t output_len, 0340 const unsigned char *additional, 0341 size_t add_len); 0342 0343 /** 0344 * \brief This function uses HMAC_DRBG to generate random data. 0345 * 0346 * This function automatically reseeds if the reseed counter is exceeded 0347 * or prediction resistance is enabled. 0348 */ 0349 #if defined(MBEDTLS_THREADING_C) 0350 /** 0351 * \note When Mbed TLS is built with threading support, 0352 * it is safe to call mbedtls_ctr_drbg_random() 0353 * from multiple threads. Other operations, including 0354 * reseeding, are not thread-safe. 0355 */ 0356 #endif /* MBEDTLS_THREADING_C */ 0357 /** 0358 * \param p_rng The HMAC_DRBG context. This must be a pointer to a 0359 * #mbedtls_hmac_drbg_context structure. 0360 * \param output The buffer to fill. 0361 * \param out_len The length of the buffer in bytes. 0362 * This must be at most #MBEDTLS_HMAC_DRBG_MAX_REQUEST. 0363 * 0364 * \return \c 0 if successful. 0365 * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED 0366 * if a call to the entropy source failed. 0367 * \return #MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG if 0368 * \p out_len > #MBEDTLS_HMAC_DRBG_MAX_REQUEST. 0369 */ 0370 int mbedtls_hmac_drbg_random(void *p_rng, unsigned char *output, size_t out_len); 0371 0372 /** 0373 * \brief This function resets HMAC_DRBG context to the state immediately 0374 * after initial call of mbedtls_hmac_drbg_init(). 0375 * 0376 * \param ctx The HMAC_DRBG context to free. 0377 */ 0378 void mbedtls_hmac_drbg_free(mbedtls_hmac_drbg_context *ctx); 0379 0380 #if defined(MBEDTLS_FS_IO) 0381 /** 0382 * \brief This function writes a seed file. 0383 * 0384 * \param ctx The HMAC_DRBG context. 0385 * \param path The name of the file. 0386 * 0387 * \return \c 0 on success. 0388 * \return #MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR on file error. 0389 * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED on reseed 0390 * failure. 0391 */ 0392 int mbedtls_hmac_drbg_write_seed_file(mbedtls_hmac_drbg_context *ctx, const char *path); 0393 0394 /** 0395 * \brief This function reads and updates a seed file. The seed 0396 * is added to this instance. 0397 * 0398 * \param ctx The HMAC_DRBG context. 0399 * \param path The name of the file. 0400 * 0401 * \return \c 0 on success. 0402 * \return #MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR on file error. 0403 * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED on 0404 * reseed failure. 0405 * \return #MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG if the existing 0406 * seed file is too large. 0407 */ 0408 int mbedtls_hmac_drbg_update_seed_file(mbedtls_hmac_drbg_context *ctx, const char *path); 0409 #endif /* MBEDTLS_FS_IO */ 0410 0411 0412 #if defined(MBEDTLS_SELF_TEST) 0413 /** 0414 * \brief The HMAC_DRBG Checkup routine. 0415 * 0416 * \return \c 0 if successful. 0417 * \return \c 1 if the test failed. 0418 */ 0419 int mbedtls_hmac_drbg_self_test(int verbose); 0420 #endif 0421 0422 #ifdef __cplusplus 0423 } 0424 #endif 0425 0426 #endif /* hmac_drbg.h */
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