entropy.h

00001 /**
00002  * \file entropy.h
00003  *
00004  * \brief Entropy accumulator implementation
00005  *
00006  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
00007  *  SPDX-License-Identifier: Apache-2.0
00008  *
00009  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
00010  *  not use this file except in compliance with the License.
00011  *  You may obtain a copy of the License at
00012  *
00013  *  http://www.apache.org/licenses/LICENSE-2.0
00014  *
00015  *  Unless required by applicable law or agreed to in writing, software
00016  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
00017  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00018  *  See the License for the specific language governing permissions and
00019  *  limitations under the License.
00020  *
00021  *  This file is part of mbed TLS (https://tls.mbed.org)
00022  */
00023 #ifndef MBEDTLS_ENTROPY_H
00024 #define MBEDTLS_ENTROPY_H
00025 
00026 #if !defined(MBEDTLS_CONFIG_FILE)
00027 #include "config.h"
00028 #else
00029 #include MBEDTLS_CONFIG_FILE
00030 #endif
00031 
00032 #include <stddef.h>
00033 
00034 #if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256)
00035 #include "sha512.h"
00036 #define MBEDTLS_ENTROPY_SHA512_ACCUMULATOR
00037 #else
00038 #if defined(MBEDTLS_SHA256_C)
00039 #define MBEDTLS_ENTROPY_SHA256_ACCUMULATOR
00040 #include "sha256.h"
00041 #endif
00042 #endif
00043 
00044 #if defined(MBEDTLS_THREADING_C)
00045 #include "threading.h"
00046 #endif
00047 
00048 #if defined(MBEDTLS_HAVEGE_C)
00049 #include "havege.h"
00050 #endif
00051 
00052 #define MBEDTLS_ERR_ENTROPY_SOURCE_FAILED                 -0x003C  /**< Critical entropy source failure. */
00053 #define MBEDTLS_ERR_ENTROPY_MAX_SOURCES                   -0x003E  /**< No more sources can be added. */
00054 #define MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED            -0x0040  /**< No sources have been added to poll. */
00055 #define MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE              -0x003D  /**< No strong sources have been added to poll. */
00056 #define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR                 -0x003F  /**< Read/write error in file. */
00057 
00058 /**
00059  * \name SECTION: Module settings
00060  *
00061  * The configuration options you can set for this module are in this section.
00062  * Either change them in config.h or define them on the compiler command line.
00063  * \{
00064  */
00065 
00066 #if !defined(MBEDTLS_ENTROPY_MAX_SOURCES)
00067 #define MBEDTLS_ENTROPY_MAX_SOURCES     20      /**< Maximum number of sources supported */
00068 #endif
00069 
00070 #if !defined(MBEDTLS_ENTROPY_MAX_GATHER)
00071 #define MBEDTLS_ENTROPY_MAX_GATHER      128     /**< Maximum amount requested from entropy sources */
00072 #endif
00073 
00074 /* \} name SECTION: Module settings */
00075 
00076 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
00077 #define MBEDTLS_ENTROPY_BLOCK_SIZE      64      /**< Block size of entropy accumulator (SHA-512) */
00078 #else
00079 #define MBEDTLS_ENTROPY_BLOCK_SIZE      32      /**< Block size of entropy accumulator (SHA-256) */
00080 #endif
00081 
00082 #define MBEDTLS_ENTROPY_MAX_SEED_SIZE   1024    /**< Maximum size of seed we read from seed file */
00083 #define MBEDTLS_ENTROPY_SOURCE_MANUAL   MBEDTLS_ENTROPY_MAX_SOURCES
00084 
00085 #define MBEDTLS_ENTROPY_SOURCE_STRONG   1       /**< Entropy source is strong   */
00086 #define MBEDTLS_ENTROPY_SOURCE_WEAK     0       /**< Entropy source is weak     */
00087 
00088 #ifdef __cplusplus
00089 extern "C" {
00090 #endif
00091 
00092 /**
00093  * \brief           Entropy poll callback pointer
00094  *
00095  * \param data      Callback-specific data pointer
00096  * \param output    Data to fill
00097  * \param len       Maximum size to provide
00098  * \param olen      The actual amount of bytes put into the buffer (Can be 0)
00099  *
00100  * \return          0 if no critical failures occurred,
00101  *                  MBEDTLS_ERR_ENTROPY_SOURCE_FAILED otherwise
00102  */
00103 typedef int (*mbedtls_entropy_f_source_ptr)(void *data, unsigned char *output, size_t len,
00104                             size_t *olen);
00105 
00106 /**
00107  * \brief           Entropy source state
00108  */
00109 typedef struct
00110 {
00111     mbedtls_entropy_f_source_ptr    f_source;   /**< The entropy source callback */
00112     void *          p_source;   /**< The callback data pointer */
00113     size_t          size;       /**< Amount received in bytes */
00114     size_t          threshold;  /**< Minimum bytes required before release */
00115     int             strong;     /**< Is the source strong? */
00116 }
00117 mbedtls_entropy_source_state;
00118 
00119 /**
00120  * \brief           Entropy context structure
00121  */
00122 typedef struct
00123 {
00124 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
00125     mbedtls_sha512_context  accumulator;
00126 #else
00127     mbedtls_sha256_context  accumulator;
00128 #endif
00129     int             source_count;
00130     mbedtls_entropy_source_state    source[MBEDTLS_ENTROPY_MAX_SOURCES];
00131 #if defined(MBEDTLS_HAVEGE_C)
00132     mbedtls_havege_state    havege_data;
00133 #endif
00134 #if defined(MBEDTLS_THREADING_C)
00135     mbedtls_threading_mutex_t mutex ;    /*!< mutex                  */
00136 #endif
00137 }
00138 mbedtls_entropy_context;
00139 
00140 /**
00141  * \brief           Initialize the context
00142  *
00143  * \param ctx       Entropy context to initialize
00144  */
00145 void mbedtls_entropy_init( mbedtls_entropy_context *ctx );
00146 
00147 /**
00148  * \brief           Free the data in the context
00149  *
00150  * \param ctx       Entropy context to free
00151  */
00152 void mbedtls_entropy_free( mbedtls_entropy_context *ctx );
00153 
00154 /**
00155  * \brief           Adds an entropy source to poll
00156  *                  (Thread-safe if MBEDTLS_THREADING_C is enabled)
00157  *
00158  * \param ctx       Entropy context
00159  * \param f_source  Entropy function
00160  * \param p_source  Function data
00161  * \param threshold Minimum required from source before entropy is released
00162  *                  ( with mbedtls_entropy_func() ) (in bytes)
00163  * \param strong    MBEDTLS_ENTROPY_SOURCE_STRONG or
00164  *                  MBEDTSL_ENTROPY_SOURCE_WEAK.
00165  *                  At least one strong source needs to be added.
00166  *                  Weaker sources (such as the cycle counter) can be used as
00167  *                  a complement.
00168  *
00169  * \return          0 if successful or MBEDTLS_ERR_ENTROPY_MAX_SOURCES
00170  */
00171 int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,
00172                         mbedtls_entropy_f_source_ptr f_source, void *p_source,
00173                         size_t threshold, int strong );
00174 
00175 /**
00176  * \brief           Trigger an extra gather poll for the accumulator
00177  *                  (Thread-safe if MBEDTLS_THREADING_C is enabled)
00178  *
00179  * \param ctx       Entropy context
00180  *
00181  * \return          0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
00182  */
00183 int mbedtls_entropy_gather( mbedtls_entropy_context *ctx );
00184 
00185 /**
00186  * \brief           Retrieve entropy from the accumulator
00187  *                  (Maximum length: MBEDTLS_ENTROPY_BLOCK_SIZE)
00188  *                  (Thread-safe if MBEDTLS_THREADING_C is enabled)
00189  *
00190  * \param data      Entropy context
00191  * \param output    Buffer to fill
00192  * \param len       Number of bytes desired, must be at most MBEDTLS_ENTROPY_BLOCK_SIZE
00193  *
00194  * \return          0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
00195  */
00196 int mbedtls_entropy_func( void *data, unsigned char *output, size_t len );
00197 
00198 /**
00199  * \brief           Add data to the accumulator manually
00200  *                  (Thread-safe if MBEDTLS_THREADING_C is enabled)
00201  *
00202  * \param ctx       Entropy context
00203  * \param data      Data to add
00204  * \param len       Length of data
00205  *
00206  * \return          0 if successful
00207  */
00208 int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx,
00209                            const unsigned char *data, size_t len );
00210 
00211 #if defined(MBEDTLS_FS_IO)
00212 /**
00213  * \brief               Write a seed file
00214  *
00215  * \param ctx           Entropy context
00216  * \param path          Name of the file
00217  *
00218  * \return              0 if successful,
00219  *                      MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, or
00220  *                      MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
00221  */
00222 int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path );
00223 
00224 /**
00225  * \brief               Read and update a seed file. Seed is added to this
00226  *                      instance. No more than MBEDTLS_ENTROPY_MAX_SEED_SIZE bytes are
00227  *                      read from the seed file. The rest is ignored.
00228  *
00229  * \param ctx           Entropy context
00230  * \param path          Name of the file
00231  *
00232  * \return              0 if successful,
00233  *                      MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error,
00234  *                      MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
00235  */
00236 int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path );
00237 #endif /* MBEDTLS_FS_IO */
00238 
00239 #if defined(MBEDTLS_SELF_TEST)
00240 /**
00241  * \brief          Checkup routine
00242  *
00243  * \return         0 if successful, or 1 if a test failed
00244  */
00245 int mbedtls_entropy_self_test( int verbose );
00246 #endif /* MBEDTLS_SELF_TEST */
00247 
00248 #ifdef __cplusplus
00249 }
00250 #endif
00251 
00252 #endif /* entropy.h */