reactos/dll/3rdparty/mbedtls/entropy.c

   1 /*
   2  *  Entropy accumulator implementation
   3  *
   4  *  Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
   5  *  SPDX-License-Identifier: GPL-2.0
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; either version 2 of the License, or
  10  *  (at your option) any later version.
  11  *
  12  *  This program is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License along
  18  *  with this program; if not, write to the Free Software Foundation, Inc.,
  19  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  *  This file is part of mbed TLS (https://tls.mbed.org)
  22  */
  23
  24 #if !defined(MBEDTLS_CONFIG_FILE)
  25 #include "mbedtls/config.h"
  26 #else
  27 #include MBEDTLS_CONFIG_FILE
  28 #endif
  29
  30 #if defined(MBEDTLS_ENTROPY_C)
  31
  32 #if defined(MBEDTLS_TEST_NULL_ENTROPY)
  33 #warning "**** WARNING!  MBEDTLS_TEST_NULL_ENTROPY defined! "
  34 #warning "**** THIS BUILD HAS NO DEFINED ENTROPY SOURCES "
  35 #warning "**** THIS BUILD IS *NOT* SUITABLE FOR PRODUCTION USE "
  36 #endif
  37
  38 #include "mbedtls/entropy.h"
  39 #include "mbedtls/entropy_poll.h"
  40
  41 #include <string.h>
  42
  43 #if defined(MBEDTLS_FS_IO)
  44 #include <stdio.h>
  45 #endif
  46
  47 #if defined(MBEDTLS_ENTROPY_NV_SEED)
  48 #include "mbedtls/platform.h"
  49 #endif
  50
  51 #if defined(MBEDTLS_SELF_TEST)
  52 #if defined(MBEDTLS_PLATFORM_C)
  53 #include "mbedtls/platform.h"
  54 #else
  55 #include <stdio.h>
  56 #define mbedtls_printf     printf
  57 #endif /* MBEDTLS_PLATFORM_C */
  58 #endif /* MBEDTLS_SELF_TEST */
  59
  60 #if defined(MBEDTLS_HAVEGE_C)
  61 #include "mbedtls/havege.h"
  62 #endif
  63
  64 /* Implementation that should never be optimized out by the compiler */
  65 static void mbedtls_zeroize( void *v, size_t n ) {
  66     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
  67 }
  68
  69 #define ENTROPY_MAX_LOOP    256     /**< Maximum amount to loop before error */
  70
  71 void mbedtls_entropy_init( mbedtls_entropy_context *ctx )
  72 {
  73     memset( ctx, 0, sizeof(mbedtls_entropy_context) );
  74
  75 #if defined(MBEDTLS_THREADING_C)
  76     mbedtls_mutex_init( &ctx->mutex );
  77 #endif
  78
  79 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
  80     mbedtls_sha512_starts( &ctx->accumulator, 0 );
  81 #else
  82     mbedtls_sha256_starts( &ctx->accumulator, 0 );
  83 #endif
  84 #if defined(MBEDTLS_HAVEGE_C)
  85     mbedtls_havege_init( &ctx->havege_data );
  86 #endif
  87
  88 #if defined(MBEDTLS_TEST_NULL_ENTROPY)
  89     mbedtls_entropy_add_source( ctx, mbedtls_null_entropy_poll, NULL,
  90                                 1, MBEDTLS_ENTROPY_SOURCE_STRONG );
  91 #endif
  92
  93 #if !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES)
  94 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
  95     mbedtls_entropy_add_source( ctx, mbedtls_platform_entropy_poll, NULL,
  96                                 MBEDTLS_ENTROPY_MIN_PLATFORM,
  97                                 MBEDTLS_ENTROPY_SOURCE_STRONG );
  98 #endif
  99 #if defined(MBEDTLS_TIMING_C)
 100     mbedtls_entropy_add_source( ctx, mbedtls_hardclock_poll, NULL,
 101                                 MBEDTLS_ENTROPY_MIN_HARDCLOCK,
 102                                 MBEDTLS_ENTROPY_SOURCE_WEAK );
 103 #endif
 104 #if defined(MBEDTLS_HAVEGE_C)
 105     mbedtls_entropy_add_source( ctx, mbedtls_havege_poll, &ctx->havege_data,
 106                                 MBEDTLS_ENTROPY_MIN_HAVEGE,
 107                                 MBEDTLS_ENTROPY_SOURCE_STRONG );
 108 #endif
 109 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
 110     mbedtls_entropy_add_source( ctx, mbedtls_hardware_poll, NULL,
 111                                 MBEDTLS_ENTROPY_MIN_HARDWARE,
 112                                 MBEDTLS_ENTROPY_SOURCE_STRONG );
 113 #endif
 114 #if defined(MBEDTLS_ENTROPY_NV_SEED)
 115     mbedtls_entropy_add_source( ctx, mbedtls_nv_seed_poll, NULL,
 116                                 MBEDTLS_ENTROPY_BLOCK_SIZE,
 117                                 MBEDTLS_ENTROPY_SOURCE_STRONG );
 118 #endif
 119 #endif /* MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES */
 120 }
 121
 122 void mbedtls_entropy_free( mbedtls_entropy_context *ctx )
 123 {
 124 #if defined(MBEDTLS_HAVEGE_C)
 125     mbedtls_havege_free( &ctx->havege_data );
 126 #endif
 127 #if defined(MBEDTLS_THREADING_C)
 128     mbedtls_mutex_free( &ctx->mutex );
 129 #endif
 130     mbedtls_zeroize( ctx, sizeof( mbedtls_entropy_context ) );
 131 }
 132
 133 int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,
 134                         mbedtls_entropy_f_source_ptr f_source, void *p_source,
 135                         size_t threshold, int strong )
 136 {
 137     int index, ret = 0;
 138
 139 #if defined(MBEDTLS_THREADING_C)
 140     if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
 141         return( ret );
 142 #endif
 143
 144     index = ctx->source_count;
 145     if( index >= MBEDTLS_ENTROPY_MAX_SOURCES )
 146     {
 147         ret = MBEDTLS_ERR_ENTROPY_MAX_SOURCES;
 148         goto exit;
 149     }
 150
 151     ctx->source[index].f_source  = f_source;
 152     ctx->source[index].p_source  = p_source;
 153     ctx->source[index].threshold = threshold;
 154     ctx->source[index].strong    = strong;
 155
 156     ctx->source_count++;
 157
 158 exit:
 159 #if defined(MBEDTLS_THREADING_C)
 160     if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
 161         return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
 162 #endif
 163
 164     return( ret );
 165 }
 166
 167 /*
 168  * Entropy accumulator update
 169  */
 170 static int entropy_update( mbedtls_entropy_context *ctx, unsigned char source_id,
 171                            const unsigned char *data, size_t len )
 172 {
 173     unsigned char header[2];
 174     unsigned char tmp[MBEDTLS_ENTROPY_BLOCK_SIZE];
 175     size_t use_len = len;
 176     const unsigned char *p = data;
 177
 178     if( use_len > MBEDTLS_ENTROPY_BLOCK_SIZE )
 179     {
 180 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
 181         mbedtls_sha512( data, len, tmp, 0 );
 182 #else
 183         mbedtls_sha256( data, len, tmp, 0 );
 184 #endif
 185         p = tmp;
 186         use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
 187     }
 188
 189     header[0] = source_id;
 190     header[1] = use_len & 0xFF;
 191
 192 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
 193     mbedtls_sha512_update( &ctx->accumulator, header, 2 );
 194     mbedtls_sha512_update( &ctx->accumulator, p, use_len );
 195 #else
 196     mbedtls_sha256_update( &ctx->accumulator, header, 2 );
 197     mbedtls_sha256_update( &ctx->accumulator, p, use_len );
 198 #endif
 199
 200     return( 0 );
 201 }
 202
 203 int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx,
 204                            const unsigned char *data, size_t len )
 205 {
 206     int ret;
 207
 208 #if defined(MBEDTLS_THREADING_C)
 209     if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
 210         return( ret );
 211 #endif
 212
 213     ret = entropy_update( ctx, MBEDTLS_ENTROPY_SOURCE_MANUAL, data, len );
 214
 215 #if defined(MBEDTLS_THREADING_C)
 216     if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
 217         return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
 218 #endif
 219
 220     return( ret );
 221 }
 222
 223 /*
 224  * Run through the different sources to add entropy to our accumulator
 225  */
 226 static int entropy_gather_internal( mbedtls_entropy_context *ctx )
 227 {
 228     int ret, i, have_one_strong = 0;
 229     unsigned char buf[MBEDTLS_ENTROPY_MAX_GATHER];
 230     size_t olen;
 231
 232     if( ctx->source_count == 0 )
 233         return( MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED );
 234
 235     /*
 236      * Run through our entropy sources
 237      */
 238     for( i = 0; i < ctx->source_count; i++ )
 239     {
 240         if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG )
 241             have_one_strong = 1;
 242
 243         olen = 0;
 244         if( ( ret = ctx->source[i].f_source( ctx->source[i].p_source,
 245                         buf, MBEDTLS_ENTROPY_MAX_GATHER, &olen ) ) != 0 )
 246         {
 247             return( ret );
 248         }
 249
 250         /*
 251          * Add if we actually gathered something
 252          */
 253         if( olen > 0 )
 254         {
 255             entropy_update( ctx, (unsigned char) i, buf, olen );
 256             ctx->source[i].size += olen;
 257         }
 258     }
 259
 260     if( have_one_strong == 0 )
 261         return( MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE );
 262
 263     return( 0 );
 264 }
 265
 266 /*
 267  * Thread-safe wrapper for entropy_gather_internal()
 268  */
 269 int mbedtls_entropy_gather( mbedtls_entropy_context *ctx )
 270 {
 271     int ret;
 272
 273 #if defined(MBEDTLS_THREADING_C)
 274     if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
 275         return( ret );
 276 #endif
 277
 278     ret = entropy_gather_internal( ctx );
 279
 280 #if defined(MBEDTLS_THREADING_C)
 281     if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
 282         return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
 283 #endif
 284
 285     return( ret );
 286 }
 287
 288 int mbedtls_entropy_func( void *data, unsigned char *output, size_t len )
 289 {
 290     int ret, count = 0, i, done;
 291     mbedtls_entropy_context *ctx = (mbedtls_entropy_context *) data;
 292     unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
 293
 294     if( len > MBEDTLS_ENTROPY_BLOCK_SIZE )
 295         return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
 296
 297 #if defined(MBEDTLS_ENTROPY_NV_SEED)
 298     /* Update the NV entropy seed before generating any entropy for outside
 299      * use.
 300      */
 301     if( ctx->initial_entropy_run == 0 )
 302     {
 303         ctx->initial_entropy_run = 1;
 304         if( ( ret = mbedtls_entropy_update_nv_seed( ctx ) ) != 0 )
 305             return( ret );
 306     }
 307 #endif
 308
 309 #if defined(MBEDTLS_THREADING_C)
 310     if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
 311         return( ret );
 312 #endif
 313
 314     /*
 315      * Always gather extra entropy before a call
 316      */
 317     do
 318     {
 319         if( count++ > ENTROPY_MAX_LOOP )
 320         {
 321             ret = MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
 322             goto exit;
 323         }
 324
 325         if( ( ret = entropy_gather_internal( ctx ) ) != 0 )
 326             goto exit;
 327
 328         done = 1;
 329         for( i = 0; i < ctx->source_count; i++ )
 330             if( ctx->source[i].size < ctx->source[i].threshold )
 331                 done = 0;
 332     }
 333     while( ! done );
 334
 335     memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
 336
 337 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
 338     mbedtls_sha512_finish( &ctx->accumulator, buf );
 339
 340     /*
 341      * Reset accumulator and counters and recycle existing entropy
 342      */
 343     memset( &ctx->accumulator, 0, sizeof( mbedtls_sha512_context ) );
 344     mbedtls_sha512_starts( &ctx->accumulator, 0 );
 345     mbedtls_sha512_update( &ctx->accumulator, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
 346
 347     /*
 348      * Perform second SHA-512 on entropy
 349      */
 350     mbedtls_sha512( buf, MBEDTLS_ENTROPY_BLOCK_SIZE, buf, 0 );
 351 #else /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
 352     mbedtls_sha256_finish( &ctx->accumulator, buf );
 353
 354     /*
 355      * Reset accumulator and counters and recycle existing entropy
 356      */
 357     memset( &ctx->accumulator, 0, sizeof( mbedtls_sha256_context ) );
 358     mbedtls_sha256_starts( &ctx->accumulator, 0 );
 359     mbedtls_sha256_update( &ctx->accumulator, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
 360
 361     /*
 362      * Perform second SHA-256 on entropy
 363      */
 364     mbedtls_sha256( buf, MBEDTLS_ENTROPY_BLOCK_SIZE, buf, 0 );
 365 #endif /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
 366
 367     for( i = 0; i < ctx->source_count; i++ )
 368         ctx->source[i].size = 0;
 369
 370     memcpy( output, buf, len );
 371
 372     ret = 0;
 373
 374 exit:
 375 #if defined(MBEDTLS_THREADING_C)
 376     if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
 377         return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
 378 #endif
 379
 380     return( ret );
 381 }
 382
 383 #if defined(MBEDTLS_ENTROPY_NV_SEED)
 384 int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx )
 385 {
 386     int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
 387     unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ];
 388
 389     /* Read new seed  and write it to NV */
 390     if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
 391         return( ret );
 392
 393     if( mbedtls_nv_seed_write( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 )
 394         return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
 395
 396     /* Manually update the remaining stream with a separator value to diverge */
 397     memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
 398     mbedtls_entropy_update_manual( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
 399
 400     return( 0 );
 401 }
 402 #endif /* MBEDTLS_ENTROPY_NV_SEED */
 403
 404 #if defined(MBEDTLS_FS_IO)
 405 int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path )
 406 {
 407     int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
 408     FILE *f;
 409     unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
 410
 411     if( ( f = fopen( path, "wb" ) ) == NULL )
 412         return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
 413
 414     if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
 415         goto exit;
 416
 417     if( fwrite( buf, 1, MBEDTLS_ENTROPY_BLOCK_SIZE, f ) != MBEDTLS_ENTROPY_BLOCK_SIZE )
 418     {
 419         ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
 420         goto exit;
 421     }
 422
 423     ret = 0;
 424
 425 exit:
 426     fclose( f );
 427     return( ret );
 428 }
 429
 430 int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path )
 431 {
 432     FILE *f;
 433     size_t n;
 434     unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ];
 435
 436     if( ( f = fopen( path, "rb" ) ) == NULL )
 437         return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
 438
 439     fseek( f, 0, SEEK_END );
 440     n = (size_t) ftell( f );
 441     fseek( f, 0, SEEK_SET );
 442
 443     if( n > MBEDTLS_ENTROPY_MAX_SEED_SIZE )
 444         n = MBEDTLS_ENTROPY_MAX_SEED_SIZE;
 445
 446     if( fread( buf, 1, n, f ) != n )
 447     {
 448         fclose( f );
 449         return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
 450     }
 451
 452     fclose( f );
 453
 454     mbedtls_entropy_update_manual( ctx, buf, n );
 455
 456     return( mbedtls_entropy_write_seed_file( ctx, path ) );
 457 }
 458 #endif /* MBEDTLS_FS_IO */
 459
 460 #if defined(MBEDTLS_SELF_TEST)
 461 #if !defined(MBEDTLS_TEST_NULL_ENTROPY)
 462 /*
 463  * Dummy source function
 464  */
 465 static int entropy_dummy_source( void *data, unsigned char *output,
 466                                  size_t len, size_t *olen )
 467 {
 468     ((void) data);
 469
 470     memset( output, 0x2a, len );
 471     *olen = len;
 472
 473     return( 0 );
 474 }
 475 #endif /* !MBEDTLS_TEST_NULL_ENTROPY */
 476
 477 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
 478
 479 static int mbedtls_entropy_source_self_test_gather( unsigned char *buf, size_t buf_len )
 480 {
 481     int ret = 0;
 482     size_t entropy_len = 0;
 483     size_t olen = 0;
 484     size_t attempts = buf_len;
 485
 486     while( attempts > 0 && entropy_len < buf_len )
 487     {
 488         if( ( ret = mbedtls_hardware_poll( NULL, buf + entropy_len,
 489             buf_len - entropy_len, &olen ) ) != 0 )
 490             return( ret );
 491
 492         entropy_len += olen;
 493         attempts--;
 494     }
 495
 496     if( entropy_len < buf_len )
 497     {
 498         ret = 1;
 499     }
 500
 501     return( ret );
 502 }
 503
 504
 505 static int mbedtls_entropy_source_self_test_check_bits( const unsigned char *buf,
 506                                                         size_t buf_len )
 507 {
 508     unsigned char set= 0xFF;
 509     unsigned char unset = 0x00;
 510     size_t i;
 511
 512     for( i = 0; i < buf_len; i++ )
 513     {
 514         set &= buf[i];
 515         unset |= buf[i];
 516     }
 517
 518     return( set == 0xFF || unset == 0x00 );
 519 }
 520
 521 /*
 522  * A test to ensure hat the entropy sources are functioning correctly
 523  * and there is no obvious failure. The test performs the following checks:
 524  *  - The entropy source is not providing only 0s (all bits unset) or 1s (all
 525  *    bits set).
 526  *  - The entropy source is not providing values in a pattern. Because the
 527  *    hardware could be providing data in an arbitrary length, this check polls
 528  *    the hardware entropy source twice and compares the result to ensure they
 529  *    are not equal.
 530  *  - The error code returned by the entropy source is not an error.
 531  */
 532 int mbedtls_entropy_source_self_test( int verbose )
 533 {
 534     int ret = 0;
 535     unsigned char buf0[2 * sizeof( unsigned long long int )];
 536     unsigned char buf1[2 * sizeof( unsigned long long int )];
 537
 538     if( verbose != 0 )
 539         mbedtls_printf( "  ENTROPY_BIAS test: " );
 540
 541     memset( buf0, 0x00, sizeof( buf0 ) );
 542     memset( buf1, 0x00, sizeof( buf1 ) );
 543
 544     if( ( ret = mbedtls_entropy_source_self_test_gather( buf0, sizeof( buf0 ) ) ) != 0 )
 545         goto cleanup;
 546     if( ( ret = mbedtls_entropy_source_self_test_gather( buf1, sizeof( buf1 ) ) ) != 0 )
 547         goto cleanup;
 548
 549     /* Make sure that the returned values are not all 0 or 1 */
 550     if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf0, sizeof( buf0 ) ) ) != 0 )
 551         goto cleanup;
 552     if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf1, sizeof( buf1 ) ) ) != 0 )
 553         goto cleanup;
 554
 555     /* Make sure that the entropy source is not returning values in a
 556      * pattern */
 557     ret = memcmp( buf0, buf1, sizeof( buf0 ) ) == 0;
 558
 559 cleanup:
 560     if( verbose != 0 )
 561     {
 562         if( ret != 0 )
 563             mbedtls_printf( "failed\n" );
 564         else
 565             mbedtls_printf( "passed\n" );
 566
 567         mbedtls_printf( "\n" );
 568     }
 569
 570     return( ret != 0 );
 571 }
 572
 573 #endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */
 574
 575 /*
 576  * The actual entropy quality is hard to test, but we can at least
 577  * test that the functions don't cause errors and write the correct
 578  * amount of data to buffers.
 579  */
 580 int mbedtls_entropy_self_test( int verbose )
 581 {
 582     int ret = 1;
 583 #if !defined(MBEDTLS_TEST_NULL_ENTROPY)
 584     mbedtls_entropy_context ctx;
 585     unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
 586     unsigned char acc[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
 587     size_t i, j;
 588 #endif /* !MBEDTLS_TEST_NULL_ENTROPY */
 589
 590     if( verbose != 0 )
 591         mbedtls_printf( "  ENTROPY test: " );
 592
 593 #if !defined(MBEDTLS_TEST_NULL_ENTROPY)
 594     mbedtls_entropy_init( &ctx );
 595
 596     /* First do a gather to make sure we have default sources */
 597     if( ( ret = mbedtls_entropy_gather( &ctx ) ) != 0 )
 598         goto cleanup;
 599
 600     ret = mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL, 16,
 601                                       MBEDTLS_ENTROPY_SOURCE_WEAK );
 602     if( ret != 0 )
 603         goto cleanup;
 604
 605     if( ( ret = mbedtls_entropy_update_manual( &ctx, buf, sizeof buf ) ) != 0 )
 606         goto cleanup;
 607
 608     /*
 609      * To test that mbedtls_entropy_func writes correct number of bytes:
 610      * - use the whole buffer and rely on ASan to detect overruns
 611      * - collect entropy 8 times and OR the result in an accumulator:
 612      *   any byte should then be 0 with probably 2^(-64), so requiring
 613      *   each of the 32 or 64 bytes to be non-zero has a false failure rate
 614      *   of at most 2^(-58) which is acceptable.
 615      */
 616     for( i = 0; i < 8; i++ )
 617     {
 618         if( ( ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) ) ) != 0 )
 619             goto cleanup;
 620
 621         for( j = 0; j < sizeof( buf ); j++ )
 622             acc[j] |= buf[j];
 623     }
 624
 625     for( j = 0; j < sizeof( buf ); j++ )
 626     {
 627         if( acc[j] == 0 )
 628         {
 629             ret = 1;
 630             goto cleanup;
 631         }
 632     }
 633
 634 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
 635     if( ( ret = mbedtls_entropy_source_self_test( 0 ) ) != 0 )
 636         goto cleanup;
 637 #endif
 638
 639 cleanup:
 640     mbedtls_entropy_free( &ctx );
 641 #endif /* !MBEDTLS_TEST_NULL_ENTROPY */
 642
 643     if( verbose != 0 )
 644     {
 645         if( ret != 0 )
 646             mbedtls_printf( "failed\n" );
 647         else
 648             mbedtls_printf( "passed\n" );
 649
 650         mbedtls_printf( "\n" );
 651     }
 652
 653     return( ret != 0 );
 654 }
 655 #endif /* MBEDTLS_SELF_TEST */
 656
 657 #endif /* MBEDTLS_ENTROPY_C */