| /** |
| * \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 |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may |
| * not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| #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 |
| */ |
| #define MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG -0x0003 /**< Too many random requested in single call. */ |
| #define MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG -0x0005 /**< Input too large (Entropy + additional). */ |
| #define MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR -0x0007 /**< Read/write error in file. */ |
| #define MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED -0x0009 /**< The entropy source failed. */ |
| |
| /** |
| * \name SECTION: Module settings |
| * |
| * The configuration options you can set for this module are in this section. |
| * Either change them in 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 - \p entropy_len * 3 / 2 |
| * where \p 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 Initilisation of simpified 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 - \p entropy_len |
| * where \p 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 */ |
