/** * \file ctr_drbg.h * * \brief CTR_DRBG based on AES-256 (NIST SP 800-90) * * Copyright (C) 2006-2014, ARM Limited, All Rights Reserved * * This file is part of mbed TLS (http://www.polarssl.org) * * 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_CTR_DRBG_H #define POLARSSL_CTR_DRBG_H #include #include "aes.h" #define POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED -0x0034 /**< The entropy source failed. */ #define POLARSSL_ERR_CTR_DRBG_REQUEST_TOO_BIG -0x0036 /**< Too many random requested in single call. */ #define POLARSSL_ERR_CTR_DRBG_INPUT_TOO_BIG -0x0038 /**< Input too large (Entropy + additional). */ #define POLARSSL_ERR_CTR_DRBG_FILE_IO_ERROR -0x003A /**< Read/write error in file. */ #define CTR_DRBG_BLOCKSIZE 16 /**< Block size used by the cipher */ #define CTR_DRBG_KEYSIZE 32 /**< Key size used by the cipher */ #define CTR_DRBG_KEYBITS ( CTR_DRBG_KEYSIZE * 8 ) #define CTR_DRBG_SEEDLEN ( CTR_DRBG_KEYSIZE + CTR_DRBG_BLOCKSIZE ) /**< The seed length (counter + AES key) */ /** * \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(CTR_DRBG_ENTROPY_LEN) #if defined(POLARSSL_SHA512_C) && !defined(POLARSSL_ENTROPY_FORCE_SHA256) #define CTR_DRBG_ENTROPY_LEN 48 /**< Amount of entropy used per seed by default (48 with SHA-512, 32 with SHA-256) */ #else #define CTR_DRBG_ENTROPY_LEN 32 /**< Amount of entropy used per seed by default (48 with SHA-512, 32 with SHA-256) */ #endif #endif #if !defined(CTR_DRBG_RESEED_INTERVAL) #define CTR_DRBG_RESEED_INTERVAL 10000 /**< Interval before reseed is performed by default */ #endif #if !defined(CTR_DRBG_MAX_INPUT) #define CTR_DRBG_MAX_INPUT 256 /**< Maximum number of additional input bytes */ #endif #if !defined(CTR_DRBG_MAX_REQUEST) #define CTR_DRBG_MAX_REQUEST 1024 /**< Maximum number of requested bytes per call */ #endif #if !defined(CTR_DRBG_MAX_SEED_INPUT) #define CTR_DRBG_MAX_SEED_INPUT 384 /**< Maximum size of (re)seed buffer */ #endif /* \} name SECTION: Module settings */ #define CTR_DRBG_PR_OFF 0 /**< No prediction resistance */ #define CTR_DRBG_PR_ON 1 /**< Prediction resistance enabled */ #ifdef __cplusplus extern "C" { #endif /** * \brief CTR_DRBG context structure */ typedef struct { unsigned char counter[16]; /*!< counter (V) */ int reseed_counter; /*!< reseed counter */ int prediction_resistance; /*!< enable prediction resistance (Automatic reseed before every random generation) */ size_t entropy_len; /*!< amount of entropy grabbed on each (re)seed */ int reseed_interval; /*!< reseed interval */ aes_context aes_ctx; /*!< AES context */ /* * Callbacks (Entropy) */ int (*f_entropy)(void *, unsigned char *, size_t); void *p_entropy; /*!< context for the entropy function */ } ctr_drbg_context; /** * \brief CTR_DRBG initialization * * Note: Personalization data can be provided in addition to the more generic * entropy source to make this instantiation as unique as possible. * * \param ctx CTR_DRBG context to be initialized * \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 * * \return 0 if successful, or * POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED */ int ctr_drbg_init( ctr_drbg_context *ctx, int (*f_entropy)(void *, unsigned char *, size_t), void *p_entropy, const unsigned char *custom, size_t len ); /** * \brief Clear CTR_CRBG context data * * \param ctx CTR_DRBG context to clear */ void ctr_drbg_free( ctr_drbg_context *ctx ); /** * \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 CTR_DRBG context * \param resistance CTR_DRBG_PR_ON or CTR_DRBG_PR_OFF */ void ctr_drbg_set_prediction_resistance( ctr_drbg_context *ctx, int resistance ); /** * \brief Set the amount of entropy grabbed on each (re)seed * (Default: CTR_DRBG_ENTROPY_LEN) * * \param ctx CTR_DRBG context * \param len Amount of entropy to grab */ void ctr_drbg_set_entropy_len( ctr_drbg_context *ctx, size_t len ); /** * \brief Set the reseed interval * (Default: CTR_DRBG_RESEED_INTERVAL) * * \param ctx CTR_DRBG context * \param interval Reseed interval */ void ctr_drbg_set_reseed_interval( ctr_drbg_context *ctx, int interval ); /** * \brief CTR_DRBG reseeding (extracts data from entropy source) * * \param ctx CTR_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_CTR_DRBG_ENTROPY_SOURCE_FAILED */ int ctr_drbg_reseed( ctr_drbg_context *ctx, const unsigned char *additional, size_t len ); /** * \brief CTR_DRBG update state * * \param ctx CTR_DRBG context * \param additional Additional data to update state with * \param add_len Length of additional data * * \note If add_len is greater than CTR_DRBG_MAX_SEED_INPUT, * only the first CTR_DRBG_MAX_SEED_INPUT bytes are used, * the remaining ones are silently discarded. */ void ctr_drbg_update( ctr_drbg_context *ctx, const unsigned char *additional, size_t add_len ); /** * \brief CTR_DRBG generate random with additional update input * * Note: Automatically reseeds if reseed_counter is reached. * * \param p_rng CTR_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 * * \return 0 if successful, or * POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED, or * POLARSSL_ERR_CTR_DRBG_REQUEST_TOO_BIG */ int ctr_drbg_random_with_add( void *p_rng, unsigned char *output, size_t output_len, const unsigned char *additional, size_t add_len ); /** * \brief CTR_DRBG generate random * * Note: Automatically reseeds if reseed_counter is reached. * * \param p_rng CTR_DRBG context * \param output Buffer to fill * \param output_len Length of the buffer * * \return 0 if successful, or * POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED, or * POLARSSL_ERR_CTR_DRBG_REQUEST_TOO_BIG */ int ctr_drbg_random( void *p_rng, unsigned char *output, size_t output_len ); #if defined(POLARSSL_FS_IO) /** * \brief Write a seed file * * \param ctx CTR_DRBG context * \param path Name of the file * * \return 0 if successful, * POLARSSL_ERR_CTR_DRBG_FILE_IO_ERROR on file error, or * POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED */ int ctr_drbg_write_seed_file( ctr_drbg_context *ctx, const char *path ); /** * \brief Read and update a seed file. Seed is added to this * instance * * \param ctx CTR_DRBG context * \param path Name of the file * * \return 0 if successful, * POLARSSL_ERR_CTR_DRBG_FILE_IO_ERROR on file error, * POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or * POLARSSL_ERR_CTR_DRBG_INPUT_TOO_BIG */ int ctr_drbg_update_seed_file( ctr_drbg_context *ctx, const char *path ); #endif /* POLARSSL_FS_IO */ /** * \brief Checkup routine * * \return 0 if successful, or 1 if the test failed */ int ctr_drbg_self_test( int verbose ); /* Internal functions (do not call directly) */ int ctr_drbg_init_entropy_len( ctr_drbg_context *, int (*)(void *, unsigned char *, size_t), void *, const unsigned char *, size_t, size_t ); #ifdef __cplusplus } #endif #endif /* ctr_drbg.h */