151 lines
4.5 KiB
C
151 lines
4.5 KiB
C
/**
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* \file entropy.h
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*
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* \brief Entropy accumulator implementation
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*
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* Copyright (C) 2006-2011, Brainspark B.V.
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*
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* This file is part of PolarSSL (http://www.polarssl.org)
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* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef POLARSSL_ENTROPY_H
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#define POLARSSL_ENTROPY_H
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#include <string.h>
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#include "config.h"
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#include "sha4.h"
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#if defined(POLARSSL_HAVEGE_C)
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#include "havege.h"
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#endif
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#define POLARSSL_ERR_ENTROPY_SOURCE_FAILED -0x003C /**< Critical entropy source failure. */
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#define POLARSSL_ERR_ENTROPY_MAX_SOURCES -0x003E /**< No more sources can be added. */
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#define POLARSSL_ERR_ENTROPY_NO_SOURCES_DEFINED -0x0040 /**< No sources have been added to poll. */
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#define ENTROPY_MAX_SOURCES 20 /**< Maximum number of sources supported */
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#define ENTROPY_MAX_GATHER 128 /**< Maximum amount requested from entropy sources */
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#define ENTROPY_BLOCK_SIZE 64 /**< Block size of entropy accumulator (SHA-512) */
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#define ENTROPY_SOURCE_MANUAL ENTROPY_MAX_SOURCES
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* \brief Entropy poll callback pointer
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*
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* \param data Callback-specific data pointer
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* \param output Data to fill
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* \param len Maximum size to provide
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* \param olen The actual amount of bytes put into the buffer (Can be 0)
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*
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* \return 0 if no critical failures occurred,
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* POLARSSL_ERR_ENTROPY_SOURCE_FAILED otherwise
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*/
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typedef int (*f_source_ptr)(void *, unsigned char *, size_t, size_t *);
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/**
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* \brief Entropy source state
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*/
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typedef struct
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{
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f_source_ptr f_source; /**< The entropy source callback */
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void * p_source; /**< The callback data pointer */
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size_t size; /**< Amount received */
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size_t threshold; /**< Minimum level required before release */
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}
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source_state;
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/**
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* \brief Entropy context structure
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*/
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typedef struct
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{
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sha4_context accumulator;
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int source_count;
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source_state source[ENTROPY_MAX_SOURCES];
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#if defined(POLARSSL_HAVEGE_C)
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havege_state havege_data;
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#endif
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}
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entropy_context;
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/**
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* \brief Initialize the context
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*
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* \param ctx Entropy context to initialize
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*/
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void entropy_init( entropy_context *ctx );
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/**
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* \brief Adds an entropy source to poll
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*
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* \param ctx Entropy context
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* \param f_source Entropy function
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* \param p_source Function data
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* \param threshold Minimum required from source before entropy is released
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* ( with entropy_func() )
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*
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* \return 0 if successful or POLARSSL_ERR_ENTROPY_MAX_SOURCES
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*/
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int entropy_add_source( entropy_context *ctx,
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f_source_ptr f_source, void *p_source,
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size_t threshold );
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/**
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* \brief Trigger an extra gather poll for the accumulator
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*
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* \param ctx Entropy context
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*
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* \return 0 if successful, or POLARSSL_ERR_ENTROPY_SOURCE_FAILED
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*/
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int entropy_gather( entropy_context *ctx );
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/**
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* \brief Retrieve entropy from the accumulator (Max ENTROPY_BLOCK_SIZE)
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*
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* \param data Entropy context
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* \param output Buffer to fill
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* \param len Length of buffer
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*
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* \return 0 if successful, or POLARSSL_ERR_ENTROPY_SOURCE_FAILED
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*/
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int entropy_func( void *data, unsigned char *output, size_t len );
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/**
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* \brief Add data to the accumulator manually
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*
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* \param ctx Entropy context
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* \param data Data to add
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* \param len Length of data
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*
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* \return 0 if successful
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*/
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int entropy_update_manual( entropy_context *ctx,
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const unsigned char *data, size_t len );
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#ifdef __cplusplus
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}
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#endif
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#endif /* entropy.h */
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