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/**
* \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 */