entropy.h

00001 /**
00002  * \file entropy.h
00003  *
00004  * \brief Entropy accumulator implementation
00005  */
00006 /*
00007  *  Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
00008  *  SPDX-License-Identifier: Apache-2.0
00009  *
00010  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
00011  *  not use this file except in compliance with the License.
00012  *  You may obtain a copy of the License at
00013  *
00014  *  http://www.apache.org/licenses/LICENSE-2.0
00015  *
00016  *  Unless required by applicable law or agreed to in writing, software
00017  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
00018  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00019  *  See the License for the specific language governing permissions and
00020  *  limitations under the License.
00021  *
00022  *  This file is part of mbed TLS (https://tls.mbed.org)
00023  */
00024 #ifndef MBEDTLS_ENTROPY_H
00025 #define MBEDTLS_ENTROPY_H
00026 
00027 #if !defined(MBEDTLS_CONFIG_FILE)
00028 #include "mbedtls/config.h"
00029 #else
00030 #include MBEDTLS_CONFIG_FILE
00031 #endif
00032 
00033 #include <stddef.h>
00034 
00035 #if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256)
00036 #include "mbedtls/sha512.h"
00037 #define MBEDTLS_ENTROPY_SHA512_ACCUMULATOR
00038 #else
00039 #if defined(MBEDTLS_SHA256_C)
00040 #define MBEDTLS_ENTROPY_SHA256_ACCUMULATOR
00041 #include "mbedtls/sha256.h"
00042 #endif
00043 #endif
00044 
00045 #if defined(MBEDTLS_THREADING_C)
00046 #include "mbedtls/threading.h"
00047 #endif
00048 
00049 #if defined(MBEDTLS_HAVEGE_C)
00050 #include "mbedtls/havege.h"
00051 #endif
00052 
00053 #define MBEDTLS_ERR_ENTROPY_SOURCE_FAILED                 -0x003C  /**< Critical entropy source failure. */
00054 #define MBEDTLS_ERR_ENTROPY_MAX_SOURCES                   -0x003E  /**< No more sources can be added. */
00055 #define MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED            -0x0040  /**< No sources have been added to poll. */
00056 #define MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE              -0x003D  /**< No strong sources have been added to poll. */
00057 #define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR                 -0x003F  /**< Read/write error in file. */
00058 
00059 /**
00060  * \name SECTION: Module settings
00061  *
00062  * The configuration options you can set for this module are in this section.
00063  * Either change them in config.h or define them on the compiler command line.
00064  * \{
00065  */
00066 
00067 #if !defined(MBEDTLS_ENTROPY_MAX_SOURCES)
00068 #define MBEDTLS_ENTROPY_MAX_SOURCES     20      /**< Maximum number of sources supported */
00069 #endif
00070 
00071 #if !defined(MBEDTLS_ENTROPY_MAX_GATHER)
00072 #define MBEDTLS_ENTROPY_MAX_GATHER      128     /**< Maximum amount requested from entropy sources */
00073 #endif
00074 
00075 /* \} name SECTION: Module settings */
00076 
00077 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
00078 #define MBEDTLS_ENTROPY_BLOCK_SIZE      64      /**< Block size of entropy accumulator (SHA-512) */
00079 #else
00080 #define MBEDTLS_ENTROPY_BLOCK_SIZE      32      /**< Block size of entropy accumulator (SHA-256) */
00081 #endif
00082 
00083 #define MBEDTLS_ENTROPY_MAX_SEED_SIZE   1024    /**< Maximum size of seed we read from seed file */
00084 #define MBEDTLS_ENTROPY_SOURCE_MANUAL   MBEDTLS_ENTROPY_MAX_SOURCES
00085 
00086 #define MBEDTLS_ENTROPY_SOURCE_STRONG   1       /**< Entropy source is strong   */
00087 #define MBEDTLS_ENTROPY_SOURCE_WEAK     0       /**< Entropy source is weak     */
00088 
00089 #ifdef __cplusplus
00090 extern "C" {
00091 #endif
00092 
00093 /**
00094  * \brief           Entropy poll callback pointer
00095  *
00096  * \param data      Callback-specific data pointer
00097  * \param output    Data to fill
00098  * \param len       Maximum size to provide
00099  * \param olen      The actual amount of bytes put into the buffer (Can be 0)
00100  *
00101  * \return          0 if no critical failures occurred,
00102  *                  MBEDTLS_ERR_ENTROPY_SOURCE_FAILED otherwise
00103  */
00104 typedef int (*mbedtls_entropy_f_source_ptr)(void *data, unsigned char *output, size_t len,
00105                             size_t *olen);
00106 
00107 /**
00108  * \brief           Entropy source state
00109  */
00110 typedef struct mbedtls_entropy_source_state
00111 {
00112     mbedtls_entropy_f_source_ptr    f_source;   /**< The entropy source callback */
00113     void *          p_source;   /**< The callback data pointer */
00114     size_t          size;       /**< Amount received in bytes */
00115     size_t          threshold;  /**< Minimum bytes required before release */
00116     int             strong;     /**< Is the source strong? */
00117 }
00118 mbedtls_entropy_source_state;
00119 
00120 /**
00121  * \brief           Entropy context structure
00122  */
00123 typedef struct mbedtls_entropy_context
00124 {
00125     int accumulator_started;
00126 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
00127     mbedtls_sha512_context  accumulator;
00128 #else
00129     mbedtls_sha256_context  accumulator;
00130 #endif
00131     int             source_count;
00132     mbedtls_entropy_source_state    source[MBEDTLS_ENTROPY_MAX_SOURCES];
00133 #if defined(MBEDTLS_HAVEGE_C)
00134     mbedtls_havege_state    havege_data;
00135 #endif
00136 #if defined(MBEDTLS_THREADING_C)
00137     mbedtls_threading_mutex_t mutex ;    /*!< mutex                  */
00138 #endif
00139 #if defined(MBEDTLS_ENTROPY_NV_SEED)
00140     int initial_entropy_run;
00141 #endif
00142 }
00143 mbedtls_entropy_context;
00144 
00145 /**
00146  * \brief           Initialize the context
00147  *
00148  * \param ctx       Entropy context to initialize
00149  */
00150 void mbedtls_entropy_init( mbedtls_entropy_context *ctx );
00151 
00152 /**
00153  * \brief           Free the data in the context
00154  *
00155  * \param ctx       Entropy context to free
00156  */
00157 void mbedtls_entropy_free( mbedtls_entropy_context *ctx );
00158 
00159 /**
00160  * \brief           Adds an entropy source to poll
00161  *                  (Thread-safe if MBEDTLS_THREADING_C is enabled)
00162  *
00163  * \param ctx       Entropy context
00164  * \param f_source  Entropy function
00165  * \param p_source  Function data
00166  * \param threshold Minimum required from source before entropy is released
00167  *                  ( with mbedtls_entropy_func() ) (in bytes)
00168  * \param strong    MBEDTLS_ENTROPY_SOURCE_STRONG or
00169  *                  MBEDTLS_ENTROPY_SOURCE_WEAK.
00170  *                  At least one strong source needs to be added.
00171  *                  Weaker sources (such as the cycle counter) can be used as
00172  *                  a complement.
00173  *
00174  * \return          0 if successful or MBEDTLS_ERR_ENTROPY_MAX_SOURCES
00175  */
00176 int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,
00177                         mbedtls_entropy_f_source_ptr f_source, void *p_source,
00178                         size_t threshold, int strong );
00179 
00180 /**
00181  * \brief           Trigger an extra gather poll for the accumulator
00182  *                  (Thread-safe if MBEDTLS_THREADING_C is enabled)
00183  *
00184  * \param ctx       Entropy context
00185  *
00186  * \return          0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
00187  */
00188 int mbedtls_entropy_gather( mbedtls_entropy_context *ctx );
00189 
00190 /**
00191  * \brief           Retrieve entropy from the accumulator
00192  *                  (Maximum length: MBEDTLS_ENTROPY_BLOCK_SIZE)
00193  *                  (Thread-safe if MBEDTLS_THREADING_C is enabled)
00194  *
00195  * \param data      Entropy context
00196  * \param output    Buffer to fill
00197  * \param len       Number of bytes desired, must be at most MBEDTLS_ENTROPY_BLOCK_SIZE
00198  *
00199  * \return          0 if successful, or MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
00200  */
00201 int mbedtls_entropy_func( void *data, unsigned char *output, size_t len );
00202 
00203 /**
00204  * \brief           Add data to the accumulator manually
00205  *                  (Thread-safe if MBEDTLS_THREADING_C is enabled)
00206  *
00207  * \param ctx       Entropy context
00208  * \param data      Data to add
00209  * \param len       Length of data
00210  *
00211  * \return          0 if successful
00212  */
00213 int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx,
00214                            const unsigned char *data, size_t len );
00215 
00216 #if defined(MBEDTLS_ENTROPY_NV_SEED)
00217 /**
00218  * \brief           Trigger an update of the seed file in NV by using the
00219  *                  current entropy pool.
00220  *
00221  * \param ctx       Entropy context
00222  *
00223  * \return          0 if successful
00224  */
00225 int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx );
00226 #endif /* MBEDTLS_ENTROPY_NV_SEED */
00227 
00228 #if defined(MBEDTLS_FS_IO)
00229 /**
00230  * \brief               Write a seed file
00231  *
00232  * \param ctx           Entropy context
00233  * \param path          Name of the file
00234  *
00235  * \return              0 if successful,
00236  *                      MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error, or
00237  *                      MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
00238  */
00239 int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path );
00240 
00241 /**
00242  * \brief               Read and update a seed file. Seed is added to this
00243  *                      instance. No more than MBEDTLS_ENTROPY_MAX_SEED_SIZE bytes are
00244  *                      read from the seed file. The rest is ignored.
00245  *
00246  * \param ctx           Entropy context
00247  * \param path          Name of the file
00248  *
00249  * \return              0 if successful,
00250  *                      MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR on file error,
00251  *                      MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
00252  */
00253 int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path );
00254 #endif /* MBEDTLS_FS_IO */
00255 
00256 #if defined(MBEDTLS_SELF_TEST)
00257 /**
00258  * \brief          Checkup routine
00259  *
00260  *                 This module self-test also calls the entropy self-test,
00261  *                 mbedtls_entropy_source_self_test();
00262  *
00263  * \return         0 if successful, or 1 if a test failed
00264  */
00265 int mbedtls_entropy_self_test( int verbose );
00266 
00267 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
00268 /**
00269  * \brief          Checkup routine
00270  *
00271  *                 Verifies the integrity of the hardware entropy source
00272  *                 provided by the function 'mbedtls_hardware_poll()'.
00273  *
00274  *                 Note this is the only hardware entropy source that is known
00275  *                 at link time, and other entropy sources configured
00276  *                 dynamically at runtime by the function
00277  *                 mbedtls_entropy_add_source() will not be tested.
00278  *
00279  * \return         0 if successful, or 1 if a test failed
00280  */
00281 int mbedtls_entropy_source_self_test( int verbose );
00282 #endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */
00283 #endif /* MBEDTLS_SELF_TEST */
00284 
00285 #ifdef __cplusplus
00286 }
00287 #endif
00288 
00289 #endif /* entropy.h */