/** * \file hmac_drbg.h * * \brief HMAC_DRBG (NIST SP 800-90A) * * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved * 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. * * This file is part of mbed TLS (https://tls.mbed.org) */ #ifndef MBEDTLS_HMAC_DRBG_H #define MBEDTLS_HMAC_DRBG_H #include "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 { /* Working state: the key K is not stored explicitely, * but is implied by the HMAC context */ mbedtls_md_context_t md_ctx; /*!< HMAC context (inc. K) */ unsigned char V[MBEDTLS_MD_MAX_SIZE]; /*!< V in the spec */ int reseed_counter; /*!< reseed counter */ /* Administrative state */ size_t entropy_len; /*!< entropy bytes grabbed on each (re)seed */ int prediction_resistance; /*!< enable prediction resistance (Automatic reseed before every random generation) */ int reseed_interval; /*!< reseed interval */ /* Callbacks */ int (*f_entropy)(void *, unsigned char *, size_t); /*!< entropy function */ void *p_entropy; /*!< context for the entropy function */ #if defined(MBEDTLS_THREADING_C) mbedtls_threading_mutex_t mutex; #endif } mbedtls_hmac_drbg_context; /** * \brief HMAC_DRBG context initialization * Makes the context ready for mbedtls_hmac_drbg_seed(), * mbedtls_hmac_drbg_seed_buf() or * mbedtls_hmac_drbg_free(). * * \param ctx HMAC_DRBG context to be initialized */ void mbedtls_hmac_drbg_init( mbedtls_hmac_drbg_context *ctx ); /** * \brief HMAC_DRBG initial seeding * Seed and setup entropy source for future reseeds. * * \param ctx HMAC_DRBG context to be seeded * \param md_info MD algorithm to use for HMAC_DRBG * \param f_entropy Entropy callback (p_entropy, buffer to fill, buffer * length) * \param p_entropy Entropy context * \param custom Personalization data (Device specific identifiers) * (Can be NULL) * \param len Length of personalization data * * \note The "security strength" as defined by NIST is set to: * 128 bits if md_alg is SHA-1, * 192 bits if md_alg is SHA-224, * 256 bits if md_alg is SHA-256 or higher. * Note that SHA-256 is just as efficient as SHA-224. * * \return 0 if successful, or * MBEDTLS_ERR_MD_BAD_INPUT_DATA, or * MBEDTLS_ERR_MD_ALLOC_FAILED, or * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_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). * (For use with deterministic ECDSA.) * * \param ctx HMAC_DRBG context to be initialised * \param md_info MD algorithm to use for HMAC_DRBG * \param data Concatenation of entropy string and additional data * \param data_len Length of data in bytes * * \return 0 if successful, or * MBEDTLS_ERR_MD_BAD_INPUT_DATA, or * MBEDTLS_ERR_MD_ALLOC_FAILED. */ 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 Enable / disable prediction resistance (Default: Off) * * Note: If enabled, entropy is used for ctx->entropy_len before each call! * Only use this if you have ample supply of good entropy! * * \param ctx 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 Set the amount of entropy grabbed on each reseed * (Default: given by the security strength, which * depends on the hash used, see \c mbedtls_hmac_drbg_init() ) * * \param ctx HMAC_DRBG context * \param len 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 * (Default: MBEDTLS_HMAC_DRBG_RESEED_INTERVAL) * * \param ctx HMAC_DRBG context * \param interval Reseed interval */ void mbedtls_hmac_drbg_set_reseed_interval( mbedtls_hmac_drbg_context *ctx, int interval ); /** * \brief HMAC_DRBG update state * * \param ctx HMAC_DRBG context * \param additional Additional data to update state with, or NULL * \param add_len Length of additional data, or 0 * * \note Additional data is optional, pass NULL and 0 as second * third argument if no additional data is being used. */ void mbedtls_hmac_drbg_update( mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t add_len ); /** * \brief HMAC_DRBG reseeding (extracts data from entropy source) * * \param ctx HMAC_DRBG context * \param additional Additional data to add to state (Can be NULL) * \param len Length of additional data * * \return 0 if successful, or * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED */ int mbedtls_hmac_drbg_reseed( mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t len ); /** * \brief HMAC_DRBG generate random with additional update input * * Note: Automatically reseeds if reseed_counter is reached or PR is enabled. * * \param p_rng HMAC_DRBG context * \param output Buffer to fill * \param output_len Length of the buffer * \param additional Additional data to update with (can be NULL) * \param add_len Length of additional data (can be 0) * * \return 0 if successful, or * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or * MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG, or * MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG. */ 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 HMAC_DRBG generate random * * Note: Automatically reseeds if reseed_counter is reached or PR is enabled. * * \param p_rng HMAC_DRBG context * \param output Buffer to fill * \param out_len Length of the buffer * * \return 0 if successful, or * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or * MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG */ int mbedtls_hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len ); /** * \brief Free an HMAC_DRBG context * * \param ctx HMAC_DRBG context to free. */ void mbedtls_hmac_drbg_free( mbedtls_hmac_drbg_context *ctx ); #if defined(MBEDTLS_FS_IO) /** * \brief Write a seed file * * \param ctx HMAC_DRBG context * \param path Name of the file * * \return 0 if successful, 1 on file error, or * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED */ int mbedtls_hmac_drbg_write_seed_file( mbedtls_hmac_drbg_context *ctx, const char *path ); /** * \brief Read and update a seed file. Seed is added to this * instance * * \param ctx HMAC_DRBG context * \param path Name of the file * * \return 0 if successful, 1 on file error, * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED or * MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG */ 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 Checkup routine * * \return 0 if successful, or 1 if the test failed */ int mbedtls_hmac_drbg_self_test( int verbose ); #endif #ifdef __cplusplus } #endif #endif /* hmac_drbg.h */