mbedtls/include/mbedtls/entropy.h
Paul Bakker 7da307105c Automatically update NV seed on initial entropy run
Update the NV entropy seed before generating any entropy for outside
use. The reason this is triggered here and not in mbedtls_entropy_init(),
is that not all entropy sources mights have been added at that time.
2016-06-01 16:34:50 +01:00

265 lines
8.5 KiB
C

/**
* \file entropy.h
*
* \brief Entropy accumulator implementation
*
* Copyright (C) 2006-2016, 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_ENTROPY_H
#define MBEDTLS_ENTROPY_H
#if !defined(MBEDTLS_CONFIG_FILE)
#include "config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#include <stddef.h>
#if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256)
#include "sha512.h"
#define MBEDTLS_ENTROPY_SHA512_ACCUMULATOR
#else
#if defined(MBEDTLS_SHA256_C)
#define MBEDTLS_ENTROPY_SHA256_ACCUMULATOR
#include "sha256.h"
#endif
#endif
#if defined(MBEDTLS_THREADING_C)
#include "threading.h"
#endif
#if defined(MBEDTLS_HAVEGE_C)
#include "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_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
{
#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
mbedtls_sha512_context accumulator;
#else
mbedtls_sha256_context accumulator;
#endif
int source_count;
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
}
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
* MBEDTSL_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
*
* \return 0 if successful, or 1 if a test failed
*/
int mbedtls_entropy_self_test( int verbose );
#endif /* MBEDTLS_SELF_TEST */
#ifdef __cplusplus
}
#endif
#endif /* entropy.h */