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/**
* \file entropy.h
*
* \brief Entropy accumulator implementation
*/
/*
* Copyright The Mbed TLS Contributors
* 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.
*/
#ifndef MBEDTLS_ENTROPY_H
#define MBEDTLS_ENTROPY_H
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#include <stddef.h>
#if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256)
#include "mbedtls/sha512.h"
#define MBEDTLS_ENTROPY_SHA512_ACCUMULATOR
#else
#if defined(MBEDTLS_SHA256_C)
#define MBEDTLS_ENTROPY_SHA256_ACCUMULATOR
#include "mbedtls/sha256.h"
#endif
#endif
#if defined(MBEDTLS_THREADING_C)
#include "mbedtls/threading.h"
#endif
#if defined(MBEDTLS_HAVEGE_C)
#include "mbedtls/havege.h"
#endif
#define MBEDTLS_ERR_ENTROPY_SOURCE_FAILED -0x003C /**< Critical entropy source failure. */
#define MBEDTLS_ERR_ENTROPY_MAX_SOURCES -0x003E /**< No more sources can be added. */
#define MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED -0x0040 /**< No sources have been added to poll. */
#define MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE -0x003D /**< No strong sources have been added to poll. */
#define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR -0x003F /**< 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(MBEDTLS_ENTROPY_MAX_SOURCES)
#define MBEDTLS_ENTROPY_MAX_SOURCES 20 /**< Maximum number of sources supported */
#endif
#if !defined(MBEDTLS_ENTROPY_MAX_GATHER)
#define MBEDTLS_ENTROPY_MAX_GATHER 128 /**< Maximum amount requested from entropy sources */
#endif
/* \} name SECTION: Module settings */
#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
#define MBEDTLS_ENTROPY_BLOCK_SIZE 64 /**< Block size of entropy accumulator (SHA-512) */
#else
#define MBEDTLS_ENTROPY_BLOCK_SIZE 32 /**< Block size of entropy accumulator (SHA-256) */
#endif
#define MBEDTLS_ENTROPY_MAX_SEED_SIZE 1024 /**< Maximum size of seed we read from seed file */
#define MBEDTLS_ENTROPY_SOURCE_MANUAL MBEDTLS_ENTROPY_MAX_SOURCES
#define MBEDTLS_ENTROPY_SOURCE_STRONG 1 /**< Entropy source is strong */
#define MBEDTLS_ENTROPY_SOURCE_WEAK 0 /**< Entropy source is weak */
#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,
* MBEDTLS_ERR_ENTROPY_SOURCE_FAILED otherwise
*/
typedef int (*mbedtls_entropy_f_source_ptr)(void *data, unsigned char *output, size_t len,
size_t *olen);
/**
* \brief Entropy source state
*/
typedef struct mbedtls_entropy_source_state
{
mbedtls_entropy_f_source_ptr f_source; /**< The entropy source callback */
void * p_source; /**< The callback data pointer */
size_t size; /**< Amount received in bytes */
size_t threshold; /**< Minimum bytes required before release */
int strong; /**< Is the source strong? */
}
mbedtls_entropy_source_state;
/**
* \brief Entropy context structure
*/
typedef struct mbedtls_entropy_context
{
int accumulator_started; /* 0 after init.
* 1 after the first update.
* -1 after free. */
#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
mbedtls_sha512_context accumulator;
#else
mbedtls_sha256_context accumulator;
#endif
int source_count; /* Number of entries used in source. */
mbedtls_entropy_source_state source[MBEDTLS_ENTROPY_MAX_SOURCES];
#if defined(MBEDTLS_HAVEGE_C)
mbedtls_havege_state havege_data;
#endif
#if defined(MBEDTLS_THREADING_C)
mbedtls_threading_mutex_t mutex; /*!< mutex */
#endif
#if defined(MBEDTLS_ENTROPY_NV_SEED)
int initial_entropy_run;
#endif
}
mbedtls_entropy_context;
/**
* \brief Initialize the context
*
* \param ctx Entropy context to initialize
*/
void mbedtls_entropy_init( mbedtls_entropy_context *ctx );
/**
* \brief Free the data in the context
*
* \param ctx Entropy context to free
*/
void mbedtls_entropy_free( mbedtls_entropy_context *ctx );
/**
* \brief Adds an entropy source to poll
* (Thread-safe if MBEDTLS_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 mbedtls_entropy_func() ) (in bytes)
* \param strong MBEDTLS_ENTROPY_SOURCE_STRONG or
* MBEDTLS_ENTROPY_SOURCE_WEAK.
* At least one strong source needs to be added.
* Weaker sources (such as the cycle counter) can be used as
* a complement.
*
* \return 0 if successful or MBEDTLS_ERR_ENTROPY_MAX_SOURCES
*/
int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,
mbedtls_entropy_f_source_ptr f_source, void *p_source,
size_t threshold, int strong );
/**
* \brief Trigger an extra gather poll for the accumulator
* (Thread-safe if MBEDTLS_THREADING_C is enabled)
*
* \param ctx Entropy context
*
* \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
*/
int mbedtls_entropy_gather( mbedtls_entropy_context *ctx );
/**
* \brief Retrieve entropy from the accumulator
* (Maximum length: MBEDTLS_ENTROPY_BLOCK_SIZE)
* (Thread-safe if MBEDTLS_THREADING_C is enabled)
*
* \param data Entropy context
* \param output Buffer to fill
* \param len Number of bytes desired, must be at most MBEDTLS_ENTROPY_BLOCK_SIZE
*
* \return 0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
*/
int mbedtls_entropy_func( void *data, unsigned char *output, size_t len );
/**
* \brief Add data to the accumulator manually
* (Thread-safe if MBEDTLS_THREADING_C is enabled)
*
* \param ctx Entropy context
* \param data Data to add
* \param len Length of data
*
* \return 0 if successful
*/
int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx,
const unsigned char *data, size_t len );
#if defined(MBEDTLS_ENTROPY_NV_SEED)
/**
* \brief Trigger an update of the seed file in NV by using the
* current entropy pool.
*
* \param ctx Entropy context
*
* \return 0 if successful
*/
int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx );
#endif /* MBEDTLS_ENTROPY_NV_SEED */
#if defined(MBEDTLS_FS_IO)
/**
* \brief Write a seed file
*
* \param ctx Entropy context
* \param path Name of the file
*
* \return 0 if successful,
* MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, or
* MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
*/
int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path );
/**
* \brief Read and update a seed file. Seed is added to this
* instance. No more than MBEDTLS_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,
* MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error,
* MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
*/
int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path );
#endif /* MBEDTLS_FS_IO */
#if defined(MBEDTLS_SELF_TEST)
/**
* \brief Checkup routine
*
* This module self-test also calls the entropy self-test,
* mbedtls_entropy_source_self_test();
*
* \return 0 if successful, or 1 if a test failed
*/
int mbedtls_entropy_self_test( int verbose );
#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
/**
* \brief Checkup routine
*
* Verifies the integrity of the hardware entropy source
* provided by the function 'mbedtls_hardware_poll()'.
*
* Note this is the only hardware entropy source that is known
* at link time, and other entropy sources configured
* dynamically at runtime by the function
* mbedtls_entropy_add_source() will not be tested.
*
* \return 0 if successful, or 1 if a test failed
*/
int mbedtls_entropy_source_self_test( int verbose );
#endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */
#endif /* MBEDTLS_SELF_TEST */
#ifdef __cplusplus
}
#endif
#endif /* entropy.h */
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