diff options
Diffstat (limited to 'include/mbedtls/hmac_drbg.h')
| -rw-r--r-- | include/mbedtls/hmac_drbg.h | 434 |
1 files changed, 434 insertions, 0 deletions
diff --git a/include/mbedtls/hmac_drbg.h b/include/mbedtls/hmac_drbg.h new file mode 100644 index 0000000..18b1b75 --- /dev/null +++ b/include/mbedtls/hmac_drbg.h @@ -0,0 +1,434 @@ +/** + * \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 -0x0003 +/** Input too large (Entropy + additional). */ +#define MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG -0x0005 +/** Read/write error in file. */ +#define MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR -0x0007 +/** The entropy source failed. */ +#define MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED -0x0009 + +/** + * \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 10000 /**< Interval before reseed is performed by default */ +#endif + +#if !defined(MBEDTLS_HMAC_DRBG_MAX_INPUT) +#define MBEDTLS_HMAC_DRBG_MAX_INPUT 256 /**< Maximum number of additional input bytes */ +#endif + +#if !defined(MBEDTLS_HMAC_DRBG_MAX_REQUEST) +#define MBEDTLS_HMAC_DRBG_MAX_REQUEST 1024 /**< Maximum number of requested bytes per call */ +#endif + +#if !defined(MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT) +#define MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT 384 /**< Maximum size of (re)seed buffer */ +#endif + +/** \} name SECTION: Module settings */ + +#define MBEDTLS_HMAC_DRBG_PR_OFF 0 /**< No prediction resistance */ +#define MBEDTLS_HMAC_DRBG_PR_ON 1 /**< Prediction resistance enabled */ + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * HMAC_DRBG context. + */ +typedef struct mbedtls_hmac_drbg_context { + /* Working state: the key K is not stored explicitly, + * but is implied by the HMAC context */ + mbedtls_md_context_t MBEDTLS_PRIVATE(md_ctx); /*!< HMAC context (inc. K) */ + unsigned char MBEDTLS_PRIVATE(V)[MBEDTLS_MD_MAX_SIZE]; /*!< V in the spec */ + int MBEDTLS_PRIVATE(reseed_counter); /*!< reseed counter */ + + /* Administrative state */ + size_t MBEDTLS_PRIVATE(entropy_len); /*!< entropy bytes grabbed on each (re)seed */ + int MBEDTLS_PRIVATE(prediction_resistance); /*!< enable prediction resistance (Automatic + reseed before every random generation) */ + int MBEDTLS_PRIVATE(reseed_interval); /*!< reseed interval */ + + /* Callbacks */ + int(*MBEDTLS_PRIVATE(f_entropy))(void *, unsigned char *, size_t); /*!< entropy function */ + void *MBEDTLS_PRIVATE(p_entropy); /*!< context for the entropy function */ + +#if defined(MBEDTLS_THREADING_C) + /* Invariant: the mutex is initialized if and only if + * md_ctx->md_info != NULL. This means that the mutex is initialized + * during the initial seeding in mbedtls_hmac_drbg_seed() or + * mbedtls_hmac_drbg_seed_buf() and freed in mbedtls_ctr_drbg_free(). + * + * Note that this invariant may change without notice. Do not rely on it + * and do not access the mutex directly in application code. + */ + mbedtls_threading_mutex_t MBEDTLS_PRIVATE(mutex); +#endif +} 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 */ |