/** * \file hmac_drbg.h * * \brief The HMAC_DRBG pseudorandom generator. * * This module implements the HMAC_DRBG pseudorandom generator described * in <em>NIST SP 800-90A: Recommendation for Random Number Generation Using * Deterministic Random Bit Generators</em>. */ /* * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later */ #ifndef MBEDTLS_HMAC_DRBG_H #define MBEDTLS_HMAC_DRBG_H #include "mbedtls/private_access.h" #include "mbedtls/build_info.h" #include "mbedtls/md.h" #if defined(MBEDTLS_THREADING_C) #include "mbedtls/threading.h" #endif /* * Error codes */ /** Too many random requested in single call. */ #define MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG … /** Input too large (Entropy + additional). */ #define MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG … /** Read/write error in file. */ #define MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR … /** The entropy source failed. */ #define MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED … /** * \name SECTION: Module settings * * The configuration options you can set for this module are in this section. * Either change them in mbedtls_config.h or define them on the compiler command line. * \{ */ #if !defined(MBEDTLS_HMAC_DRBG_RESEED_INTERVAL) #define MBEDTLS_HMAC_DRBG_RESEED_INTERVAL … #endif #if !defined(MBEDTLS_HMAC_DRBG_MAX_INPUT) #define MBEDTLS_HMAC_DRBG_MAX_INPUT … #endif #if !defined(MBEDTLS_HMAC_DRBG_MAX_REQUEST) #define MBEDTLS_HMAC_DRBG_MAX_REQUEST … #endif #if !defined(MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT) #define MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT … #endif /** \} name SECTION: Module settings */ #define MBEDTLS_HMAC_DRBG_PR_OFF … #define MBEDTLS_HMAC_DRBG_PR_ON … #ifdef __cplusplus extern "C" { #endif /** * HMAC_DRBG context. */ mbedtls_hmac_drbg_context; /** * \brief HMAC_DRBG context initialization. * * This function makes the context ready for mbedtls_hmac_drbg_seed(), * mbedtls_hmac_drbg_seed_buf() or mbedtls_hmac_drbg_free(). * * \note The reseed interval is #MBEDTLS_HMAC_DRBG_RESEED_INTERVAL * by default. Override this value by calling * mbedtls_hmac_drbg_set_reseed_interval(). * * \param ctx HMAC_DRBG context to be initialized. */ void mbedtls_hmac_drbg_init(mbedtls_hmac_drbg_context *ctx); /** * \brief HMAC_DRBG initial seeding. * * Set the initial seed and set up the entropy source for future reseeds. * * A typical choice for the \p f_entropy and \p p_entropy parameters is * to use the entropy module: * - \p f_entropy is mbedtls_entropy_func(); * - \p p_entropy is an instance of ::mbedtls_entropy_context initialized * with mbedtls_entropy_init() (which registers the platform's default * entropy sources). * * You can provide a personalization string in addition to the * entropy source, to make this instantiation as unique as possible. * * \note By default, the security strength as defined by NIST is: * - 128 bits if \p md_info is SHA-1; * - 192 bits if \p md_info is SHA-224; * - 256 bits if \p md_info is SHA-256, SHA-384 or SHA-512. * Note that SHA-256 is just as efficient as SHA-224. * The security strength can be reduced if a smaller * entropy length is set with * mbedtls_hmac_drbg_set_entropy_len(). * * \note The default entropy length is the security strength * (converted from bits to bytes). You can override * it by calling mbedtls_hmac_drbg_set_entropy_len(). * * \note During the initial seeding, this function calls * the entropy source to obtain a nonce * whose length is half the entropy length. */ #if defined(MBEDTLS_THREADING_C) /** * \note When Mbed TLS is built with threading support, * after this function returns successfully, * it is safe to call mbedtls_hmac_drbg_random() * from multiple threads. Other operations, including * reseeding, are not thread-safe. */ #endif /* MBEDTLS_THREADING_C */ /** * \param ctx HMAC_DRBG context to be seeded. * \param md_info MD algorithm to use for HMAC_DRBG. * \param f_entropy The entropy callback, taking as arguments the * \p p_entropy context, the buffer to fill, and the * length of the buffer. * \p f_entropy is always called with a length that is * less than or equal to the entropy length. * \param p_entropy The entropy context to pass to \p f_entropy. * \param custom The personalization string. * This can be \c NULL, in which case the personalization * string is empty regardless of the value of \p len. * \param len The length of the personalization string. * This must be at most #MBEDTLS_HMAC_DRBG_MAX_INPUT * and also at most * #MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT - \c entropy_len * 3 / 2 * where \c entropy_len is the entropy length * described above. * * \return \c 0 if successful. * \return #MBEDTLS_ERR_MD_BAD_INPUT_DATA if \p md_info is * invalid. * \return #MBEDTLS_ERR_MD_ALLOC_FAILED if there was not enough * memory to allocate context data. * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED * if the call to \p f_entropy failed. */ int mbedtls_hmac_drbg_seed(mbedtls_hmac_drbg_context *ctx, const mbedtls_md_info_t *md_info, int (*f_entropy)(void *, unsigned char *, size_t), void *p_entropy, const unsigned char *custom, size_t len); /** * \brief Initialisation of simplified HMAC_DRBG (never reseeds). * * This function is meant for use in algorithms that need a pseudorandom * input such as deterministic ECDSA. */ #if defined(MBEDTLS_THREADING_C) /** * \note When Mbed TLS is built with threading support, * after this function returns successfully, * it is safe to call mbedtls_hmac_drbg_random() * from multiple threads. Other operations, including * reseeding, are not thread-safe. */ #endif /* MBEDTLS_THREADING_C */ /** * \param ctx HMAC_DRBG context to be initialised. * \param md_info MD algorithm to use for HMAC_DRBG. * \param data Concatenation of the initial entropy string and * the additional data. * \param data_len Length of \p data in bytes. * * \return \c 0 if successful. or * \return #MBEDTLS_ERR_MD_BAD_INPUT_DATA if \p md_info is * invalid. * \return #MBEDTLS_ERR_MD_ALLOC_FAILED if there was not enough * memory to allocate context data. */ int mbedtls_hmac_drbg_seed_buf(mbedtls_hmac_drbg_context *ctx, const mbedtls_md_info_t *md_info, const unsigned char *data, size_t data_len); /** * \brief This function turns prediction resistance on or off. * The default value is off. * * \note If enabled, entropy is gathered at the beginning of * every call to mbedtls_hmac_drbg_random_with_add() * or mbedtls_hmac_drbg_random(). * Only use this if your entropy source has sufficient * throughput. * * \param ctx The HMAC_DRBG context. * \param resistance #MBEDTLS_HMAC_DRBG_PR_ON or #MBEDTLS_HMAC_DRBG_PR_OFF. */ void mbedtls_hmac_drbg_set_prediction_resistance(mbedtls_hmac_drbg_context *ctx, int resistance); /** * \brief This function sets the amount of entropy grabbed on each * seed or reseed. * * See the documentation of mbedtls_hmac_drbg_seed() for the default value. * * \param ctx The HMAC_DRBG context. * \param len The amount of entropy to grab, in bytes. */ void mbedtls_hmac_drbg_set_entropy_len(mbedtls_hmac_drbg_context *ctx, size_t len); /** * \brief Set the reseed interval. * * The reseed interval is the number of calls to mbedtls_hmac_drbg_random() * or mbedtls_hmac_drbg_random_with_add() after which the entropy function * is called again. * * The default value is #MBEDTLS_HMAC_DRBG_RESEED_INTERVAL. * * \param ctx The HMAC_DRBG context. * \param interval The reseed interval. */ void mbedtls_hmac_drbg_set_reseed_interval(mbedtls_hmac_drbg_context *ctx, int interval); /** * \brief This function updates the state of the HMAC_DRBG context. * * \note This function is not thread-safe. It is not safe * to call this function if another thread might be * concurrently obtaining random numbers from the same * context or updating or reseeding the same context. * * \param ctx The HMAC_DRBG context. * \param additional The data to update the state with. * If this is \c NULL, there is no additional data. * \param add_len Length of \p additional in bytes. * Unused if \p additional is \c NULL. * * \return \c 0 on success, or an error from the underlying * hash calculation. */ int mbedtls_hmac_drbg_update(mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t add_len); /** * \brief This function reseeds the HMAC_DRBG context, that is * extracts data from the entropy source. * * \note This function is not thread-safe. It is not safe * to call this function if another thread might be * concurrently obtaining random numbers from the same * context or updating or reseeding the same context. * * \param ctx The HMAC_DRBG context. * \param additional Additional data to add to the state. * If this is \c NULL, there is no additional data * and \p len should be \c 0. * \param len The length of the additional data. * This must be at most #MBEDTLS_HMAC_DRBG_MAX_INPUT * and also at most * #MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT - \c entropy_len * where \c entropy_len is the entropy length * (see mbedtls_hmac_drbg_set_entropy_len()). * * \return \c 0 if successful. * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED * if a call to the entropy function failed. */ int mbedtls_hmac_drbg_reseed(mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t len); /** * \brief This function updates an HMAC_DRBG instance with additional * data and uses it to generate random data. * * This function automatically reseeds if the reseed counter is exceeded * or prediction resistance is enabled. * * \note This function is not thread-safe. It is not safe * to call this function if another thread might be * concurrently obtaining random numbers from the same * context or updating or reseeding the same context. * * \param p_rng The HMAC_DRBG context. This must be a pointer to a * #mbedtls_hmac_drbg_context structure. * \param output The buffer to fill. * \param output_len The length of the buffer in bytes. * This must be at most #MBEDTLS_HMAC_DRBG_MAX_REQUEST. * \param additional Additional data to update with. * If this is \c NULL, there is no additional data * and \p add_len should be \c 0. * \param add_len The length of the additional data. * This must be at most #MBEDTLS_HMAC_DRBG_MAX_INPUT. * * \return \c 0 if successful. * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED * if a call to the entropy source failed. * \return #MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG if * \p output_len > #MBEDTLS_HMAC_DRBG_MAX_REQUEST. * \return #MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG if * \p add_len > #MBEDTLS_HMAC_DRBG_MAX_INPUT. */ int mbedtls_hmac_drbg_random_with_add(void *p_rng, unsigned char *output, size_t output_len, const unsigned char *additional, size_t add_len); /** * \brief This function uses HMAC_DRBG to generate random data. * * This function automatically reseeds if the reseed counter is exceeded * or prediction resistance is enabled. */ #if defined(MBEDTLS_THREADING_C) /** * \note When Mbed TLS is built with threading support, * it is safe to call mbedtls_ctr_drbg_random() * from multiple threads. Other operations, including * reseeding, are not thread-safe. */ #endif /* MBEDTLS_THREADING_C */ /** * \param p_rng The HMAC_DRBG context. This must be a pointer to a * #mbedtls_hmac_drbg_context structure. * \param output The buffer to fill. * \param out_len The length of the buffer in bytes. * This must be at most #MBEDTLS_HMAC_DRBG_MAX_REQUEST. * * \return \c 0 if successful. * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED * if a call to the entropy source failed. * \return #MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG if * \p out_len > #MBEDTLS_HMAC_DRBG_MAX_REQUEST. */ int mbedtls_hmac_drbg_random(void *p_rng, unsigned char *output, size_t out_len); /** * \brief This function resets HMAC_DRBG context to the state immediately * after initial call of mbedtls_hmac_drbg_init(). * * \param ctx The HMAC_DRBG context to free. */ void mbedtls_hmac_drbg_free(mbedtls_hmac_drbg_context *ctx); #if defined(MBEDTLS_FS_IO) /** * \brief This function writes a seed file. * * \param ctx The HMAC_DRBG context. * \param path The name of the file. * * \return \c 0 on success. * \return #MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR on file error. * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED on reseed * failure. */ int mbedtls_hmac_drbg_write_seed_file(mbedtls_hmac_drbg_context *ctx, const char *path); /** * \brief This function reads and updates a seed file. The seed * is added to this instance. * * \param ctx The HMAC_DRBG context. * \param path The name of the file. * * \return \c 0 on success. * \return #MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR on file error. * \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED on * reseed failure. * \return #MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG if the existing * seed file is too large. */ int mbedtls_hmac_drbg_update_seed_file(mbedtls_hmac_drbg_context *ctx, const char *path); #endif /* MBEDTLS_FS_IO */ #if defined(MBEDTLS_SELF_TEST) /** * \brief The HMAC_DRBG Checkup routine. * * \return \c 0 if successful. * \return \c 1 if the test failed. */ int mbedtls_hmac_drbg_self_test(int verbose); #endif #ifdef __cplusplus } #endif #endif /* hmac_drbg.h */
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