/** * \file hmac_drbg.h * * \brief HMAC_DRBG (NIST SP 800-90A) * * Copyright (C) 2014, Brainspark B.V. * * This file is part of PolarSSL (http://www.polarssl.org) * Lead Maintainer: Paul Bakker * * All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #ifndef POLARSSL_HMAC_DRBG_H #define POLARSSL_HMAC_DRBG_H #include "md.h" /* * Error codes */ #define POLARSSL_ERR_HMAC_DRBG_REQUEST_TOO_BIG -0x0003 /**< Too many random requested in single call. */ #define POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG -0x0005 /**< Input too large (Entropy + additional). */ #define POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR -0x0007 /**< Read/write error in file. */ #define POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED -0x0009 /**< The entropy source failed. */ #if !defined(POLARSSL_CONFIG_OPTIONS) #define POLARSSL_HMAC_DRBG_RESEED_INTERVAL 10000 /**< Interval before reseed is performed by default */ #define POLARSSL_HMAC_DRBG_MAX_INPUT 256 /**< Maximum number of additional input bytes */ #define POLARSSL_HMAC_DRBG_MAX_REQUEST 1024 /**< Maximum number of requested bytes per call */ #define POLARSSL_HMAC_DRBG_MAX_SEED_INPUT 384 /**< Maximum size of (re)seed buffer */ #endif /* !POLARSSL_CONFIG_OPTIONS */ #define POLARSSL_HMAC_DRBG_PR_OFF 0 /**< No prediction resistance */ #define POLARSSL_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 */ md_context_t md_ctx; /*!< HMAC context (inc. K) */ unsigned char V[POLARSSL_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 */ } hmac_drbg_context; /** * \brief HMAC_DRBG initialisation * * \param ctx HMAC_DRBG context to be initialised * \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 * POLARSSL_ERR_MD_BAD_INPUT_DATA, or * POLARSSL_ERR_MD_ALLOC_FAILED, or * POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED. */ int hmac_drbg_init( hmac_drbg_context *ctx, const 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 * POLARSSL_ERR_MD_BAD_INPUT_DATA, or * POLARSSL_ERR_MD_ALLOC_FAILED. */ int hmac_drbg_init_buf( hmac_drbg_context *ctx, const 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 POLARSSL_HMAC_DRBG_PR_ON or POLARSSL_HMAC_DRBG_PR_OFF */ void hmac_drbg_set_prediction_resistance( 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 hmac_drbg_init() ) * * \param ctx HMAC_DRBG context * \param len Amount of entropy to grab, in bytes */ void hmac_drbg_set_entropy_len( hmac_drbg_context *ctx, size_t len ); /** * \brief Set the reseed interval * (Default: POLARSSL_HMAC_DRBG_RESEED_INTERVAL) * * \param ctx HMAC_DRBG context * \param interval Reseed interval */ void hmac_drbg_set_reseed_interval( 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 hmac_drbg_update( 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 * POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED */ int hmac_drbg_reseed( 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 * POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or * POLARSSL_ERR_HMAC_DRBG_REQUEST_TOO_BIG, or * POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG. */ int 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 * POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or * POLARSSL_ERR_HMAC_DRBG_REQUEST_TOO_BIG */ int 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 hmac_drbg_free( hmac_drbg_context *ctx ); #if defined(POLARSSL_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 * POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED */ int hmac_drbg_write_seed_file( 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, * POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED or * POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG */ int hmac_drbg_update_seed_file( hmac_drbg_context *ctx, const char *path ); #endif #if defined(POLARSSL_SELF_TEST) /** * \brief Checkup routine * * \return 0 if successful, or 1 if the test failed */ int hmac_drbg_self_test( int verbose ); #endif #ifdef __cplusplus } #endif #endif /* hmac_drbg.h */