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/**
* \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 <polarssl_maintainer at polarssl.org>
*
* 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"
/*
* ! Same values as ctr_drbg.h !
*/
#define POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED -0x0001 /**< The entropy source failed. */
#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. */
#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 */