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/**
* \file entropy.h
*
* \brief Entropy accumulator implementation
*
* Copyright (C) 2006-2014, 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_ENTROPY_H
#define POLARSSL_ENTROPY_H
#include <string.h>
#if !defined(POLARSSL_CONFIG_FILE)
#include "config.h"
#else
#include POLARSSL_CONFIG_FILE
#endif
#if defined(POLARSSL_SHA512_C) && !defined(POLARSSL_ENTROPY_FORCE_SHA256)
#include "sha512.h"
#define POLARSSL_ENTROPY_SHA512_ACCUMULATOR
#else
#if defined(POLARSSL_SHA256_C)
#define POLARSSL_ENTROPY_SHA256_ACCUMULATOR
#include "sha256.h"
#endif
#endif
#if defined(POLARSSL_THREADING_C)
#include "threading.h"
#endif
#if defined(POLARSSL_HAVEGE_C)
#include "havege.h"
#endif
#define POLARSSL_ERR_ENTROPY_SOURCE_FAILED -0x003C /**< Critical entropy source failure. */
#define POLARSSL_ERR_ENTROPY_MAX_SOURCES -0x003E /**< No more sources can be added. */
#define POLARSSL_ERR_ENTROPY_NO_SOURCES_DEFINED -0x0040 /**< No sources have been added to poll. */
#define POLARSSL_ERR_ENTROPY_FILE_IO_ERROR -0x0058 /**< Read/write error in file. */
/**
* \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(ENTROPY_MAX_SOURCES)
#define ENTROPY_MAX_SOURCES 20 /**< Maximum number of sources supported */
#endif
#if !defined(ENTROPY_MAX_GATHER)
#define ENTROPY_MAX_GATHER 128 /**< Maximum amount requested from entropy sources */
#endif
/* \} name SECTION: Module settings */
#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
#define ENTROPY_BLOCK_SIZE 64 /**< Block size of entropy accumulator (SHA-512) */
#else
#define ENTROPY_BLOCK_SIZE 32 /**< Block size of entropy accumulator (SHA-256) */
#endif
#define ENTROPY_MAX_SEED_SIZE 1024 /**< Maximum size of seed we read from seed file */
#define ENTROPY_SOURCE_MANUAL ENTROPY_MAX_SOURCES
#ifdef __cplusplus
extern "C" {
#endif
/**
* \brief Entropy poll callback pointer
*
* \param data Callback-specific data pointer
* \param output Data to fill
* \param len Maximum size to provide
* \param olen The actual amount of bytes put into the buffer (Can be 0)
*
* \return 0 if no critical failures occurred,
* POLARSSL_ERR_ENTROPY_SOURCE_FAILED otherwise
*/
typedef int (*f_source_ptr)(void *data, unsigned char *output, size_t len,
size_t *olen);
/**
* \brief Entropy source state
*/
typedef struct
{
f_source_ptr f_source; /**< The entropy source callback */
void * p_source; /**< The callback data pointer */
size_t size; /**< Amount received */
size_t threshold; /**< Minimum level required before release */
}
source_state;
/**
* \brief Entropy context structure
*/
typedef struct
{
#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512_context accumulator;
#else
sha256_context accumulator;
#endif
int source_count;
source_state source[ENTROPY_MAX_SOURCES];
#if defined(POLARSSL_HAVEGE_C)
havege_state havege_data;
#endif
#if defined(POLARSSL_THREADING_C)
threading_mutex_t mutex; /*!< mutex */
#endif
}
entropy_context;
/**
* \brief Initialize the context
*
* \param ctx Entropy context to initialize
*/
void entropy_init( entropy_context *ctx );
/**
* \brief Free the data in the context
*
* \param ctx Entropy context to free
*/
void entropy_free( entropy_context *ctx );
/**
* \brief Adds an entropy source to poll
* (Thread-safe if POLARSSL_THREADING_C is enabled)
*
* \param ctx Entropy context
* \param f_source Entropy function
* \param p_source Function data
* \param threshold Minimum required from source before entropy is released
* ( with entropy_func() )
*
* \return 0 if successful or POLARSSL_ERR_ENTROPY_MAX_SOURCES
*/
int entropy_add_source( entropy_context *ctx,
f_source_ptr f_source, void *p_source,
size_t threshold );
/**
* \brief Trigger an extra gather poll for the accumulator
* (Thread-safe if POLARSSL_THREADING_C is enabled)
*
* \param ctx Entropy context
*
* \return 0 if successful, or POLARSSL_ERR_ENTROPY_SOURCE_FAILED
*/
int entropy_gather( entropy_context *ctx );
/**
* \brief Retrieve entropy from the accumulator
* (Maximum length: ENTROPY_BLOCK_SIZE)
* (Thread-safe if POLARSSL_THREADING_C is enabled)
*
* \param data Entropy context
* \param output Buffer to fill
* \param len Number of bytes desired, must be at most ENTROPY_BLOCK_SIZE
*
* \return 0 if successful, or POLARSSL_ERR_ENTROPY_SOURCE_FAILED
*/
int entropy_func( void *data, unsigned char *output, size_t len );
/**
* \brief Add data to the accumulator manually
* (Thread-safe if POLARSSL_THREADING_C is enabled)
*
* \param ctx Entropy context
* \param data Data to add
* \param len Length of data
*
* \return 0 if successful
*/
int entropy_update_manual( entropy_context *ctx,
const unsigned char *data, size_t len );
#if defined(POLARSSL_FS_IO)
/**
* \brief Write a seed file
*
* \param ctx Entropy context
* \param path Name of the file
*
* \return 0 if successful,
* POLARSSL_ERR_ENTROPY_FILE_IO_ERROR on file error, or
* POLARSSL_ERR_ENTROPY_SOURCE_FAILED
*/
int entropy_write_seed_file( entropy_context *ctx, const char *path );
/**
* \brief Read and update a seed file. Seed is added to this
* instance. No more than ENTROPY_MAX_SEED_SIZE bytes are
* read from the seed file. The rest is ignored.
*
* \param ctx Entropy context
* \param path Name of the file
*
* \return 0 if successful,
* POLARSSL_ERR_ENTROPY_FILE_IO_ERROR on file error,
* POLARSSL_ERR_ENTROPY_SOURCE_FAILED
*/
int entropy_update_seed_file( entropy_context *ctx, const char *path );
#endif /* POLARSSL_FS_IO */
#if defined(POLARSSL_SELF_TEST)
/**
* \brief Checkup routine
*
* \return 0 if successful, or 1 if a test failed
*/
int entropy_self_test( int verbose );
#endif /* POLARSSL_SELF_TEST */
#ifdef __cplusplus
}
#endif
#endif /* entropy.h */