1 // SPDX-License-Identifier: Apache-2.0 2 /* 3 * Entropy accumulator implementation 4 * 5 * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved 6 * 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may 8 * not use this file except in compliance with the License. 9 * You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, software 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 * See the License for the specific language governing permissions and 17 * limitations under the License. 18 * 19 * This file is part of mbed TLS (https://tls.mbed.org) 20 */ 21 22 #if !defined(MBEDTLS_CONFIG_FILE) 23 #include "mbedtls/config.h" 24 #else 25 #include MBEDTLS_CONFIG_FILE 26 #endif 27 28 #if defined(MBEDTLS_ENTROPY_C) 29 30 #if defined(MBEDTLS_TEST_NULL_ENTROPY) 31 #warning "**** WARNING! MBEDTLS_TEST_NULL_ENTROPY defined! " 32 #warning "**** THIS BUILD HAS NO DEFINED ENTROPY SOURCES " 33 #warning "**** THIS BUILD IS *NOT* SUITABLE FOR PRODUCTION USE " 34 #endif 35 36 #include "mbedtls/entropy.h" 37 #include "mbedtls/entropy_poll.h" 38 #include "mbedtls/platform_util.h" 39 #include "mbedtls/error.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 #define ENTROPY_MAX_LOOP 256 /**< Maximum amount to loop before error */ 65 66 void mbedtls_entropy_init( mbedtls_entropy_context *ctx ) 67 { 68 ctx->source_count = 0; 69 memset( ctx->source, 0, sizeof( ctx->source ) ); 70 71 #if defined(MBEDTLS_THREADING_C) 72 mbedtls_mutex_init( &ctx->mutex ); 73 #endif 74 75 ctx->accumulator_started = 0; 76 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 77 mbedtls_sha512_init( &ctx->accumulator ); 78 #else 79 mbedtls_sha256_init( &ctx->accumulator ); 80 #endif 81 #if defined(MBEDTLS_HAVEGE_C) 82 mbedtls_havege_init( &ctx->havege_data ); 83 #endif 84 85 /* Reminder: Update ENTROPY_HAVE_STRONG in the test files 86 * when adding more strong entropy sources here. */ 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 ctx->initial_entropy_run = 0; 119 #endif 120 #endif /* MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES */ 121 } 122 123 void mbedtls_entropy_free( mbedtls_entropy_context *ctx ) 124 { 125 #if defined(MBEDTLS_HAVEGE_C) 126 mbedtls_havege_free( &ctx->havege_data ); 127 #endif 128 #if defined(MBEDTLS_THREADING_C) 129 mbedtls_mutex_free( &ctx->mutex ); 130 #endif 131 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 132 mbedtls_sha512_free( &ctx->accumulator ); 133 #else 134 mbedtls_sha256_free( &ctx->accumulator ); 135 #endif 136 #if defined(MBEDTLS_ENTROPY_NV_SEED) 137 ctx->initial_entropy_run = 0; 138 #endif 139 ctx->source_count = 0; 140 mbedtls_platform_zeroize( ctx->source, sizeof( ctx->source ) ); 141 ctx->accumulator_started = 0; 142 } 143 144 int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx, 145 mbedtls_entropy_f_source_ptr f_source, void *p_source, 146 size_t threshold, int strong ) 147 { 148 int idx, ret = 0; 149 150 #if defined(MBEDTLS_THREADING_C) 151 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) 152 return( ret ); 153 #endif 154 155 idx = ctx->source_count; 156 if( idx >= MBEDTLS_ENTROPY_MAX_SOURCES ) 157 { 158 ret = MBEDTLS_ERR_ENTROPY_MAX_SOURCES; 159 goto exit; 160 } 161 162 ctx->source[idx].f_source = f_source; 163 ctx->source[idx].p_source = p_source; 164 ctx->source[idx].threshold = threshold; 165 ctx->source[idx].strong = strong; 166 167 ctx->source_count++; 168 169 exit: 170 #if defined(MBEDTLS_THREADING_C) 171 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) 172 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); 173 #endif 174 175 return( ret ); 176 } 177 178 /* 179 * Entropy accumulator update 180 */ 181 static int entropy_update( mbedtls_entropy_context *ctx, unsigned char source_id, 182 const unsigned char *data, size_t len ) 183 { 184 unsigned char header[2]; 185 unsigned char tmp[MBEDTLS_ENTROPY_BLOCK_SIZE]; 186 size_t use_len = len; 187 const unsigned char *p = data; 188 int ret = 0; 189 190 if( use_len > MBEDTLS_ENTROPY_BLOCK_SIZE ) 191 { 192 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 193 if( ( ret = mbedtls_sha512_ret( data, len, tmp, 0 ) ) != 0 ) 194 goto cleanup; 195 #else 196 if( ( ret = mbedtls_sha256_ret( data, len, tmp, 0 ) ) != 0 ) 197 goto cleanup; 198 #endif 199 p = tmp; 200 use_len = MBEDTLS_ENTROPY_BLOCK_SIZE; 201 } 202 203 header[0] = source_id; 204 header[1] = use_len & 0xFF; 205 206 /* 207 * Start the accumulator if this has not already happened. Note that 208 * it is sufficient to start the accumulator here only because all calls to 209 * gather entropy eventually execute this code. 210 */ 211 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 212 if( ctx->accumulator_started == 0 && 213 ( ret = mbedtls_sha512_starts_ret( &ctx->accumulator, 0 ) ) != 0 ) 214 goto cleanup; 215 else 216 ctx->accumulator_started = 1; 217 if( ( ret = mbedtls_sha512_update_ret( &ctx->accumulator, header, 2 ) ) != 0 ) 218 goto cleanup; 219 ret = mbedtls_sha512_update_ret( &ctx->accumulator, p, use_len ); 220 #else 221 if( ctx->accumulator_started == 0 && 222 ( ret = mbedtls_sha256_starts_ret( &ctx->accumulator, 0 ) ) != 0 ) 223 goto cleanup; 224 else 225 ctx->accumulator_started = 1; 226 if( ( ret = mbedtls_sha256_update_ret( &ctx->accumulator, header, 2 ) ) != 0 ) 227 goto cleanup; 228 ret = mbedtls_sha256_update_ret( &ctx->accumulator, p, use_len ); 229 #endif 230 231 cleanup: 232 mbedtls_platform_zeroize( tmp, sizeof( tmp ) ); 233 234 return( ret ); 235 } 236 237 int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx, 238 const unsigned char *data, size_t len ) 239 { 240 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 241 242 #if defined(MBEDTLS_THREADING_C) 243 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) 244 return( ret ); 245 #endif 246 247 ret = entropy_update( ctx, MBEDTLS_ENTROPY_SOURCE_MANUAL, data, len ); 248 249 #if defined(MBEDTLS_THREADING_C) 250 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) 251 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); 252 #endif 253 254 return( ret ); 255 } 256 257 /* 258 * Run through the different sources to add entropy to our accumulator 259 */ 260 static int entropy_gather_internal( mbedtls_entropy_context *ctx ) 261 { 262 int ret = MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; 263 int i; 264 int have_one_strong = 0; 265 unsigned char buf[MBEDTLS_ENTROPY_MAX_GATHER]; 266 size_t olen; 267 268 if( ctx->source_count == 0 ) 269 return( MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED ); 270 271 /* 272 * Run through our entropy sources 273 */ 274 for( i = 0; i < ctx->source_count; i++ ) 275 { 276 if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG ) 277 have_one_strong = 1; 278 279 olen = 0; 280 if( ( ret = ctx->source[i].f_source( ctx->source[i].p_source, 281 buf, MBEDTLS_ENTROPY_MAX_GATHER, &olen ) ) != 0 ) 282 { 283 goto cleanup; 284 } 285 286 /* 287 * Add if we actually gathered something 288 */ 289 if( olen > 0 ) 290 { 291 if( ( ret = entropy_update( ctx, (unsigned char) i, 292 buf, olen ) ) != 0 ) 293 return( ret ); 294 ctx->source[i].size += olen; 295 } 296 } 297 298 if( have_one_strong == 0 ) 299 ret = MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE; 300 301 cleanup: 302 mbedtls_platform_zeroize( buf, sizeof( buf ) ); 303 304 return( ret ); 305 } 306 307 /* 308 * Thread-safe wrapper for entropy_gather_internal() 309 */ 310 int mbedtls_entropy_gather( mbedtls_entropy_context *ctx ) 311 { 312 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 313 314 #if defined(MBEDTLS_THREADING_C) 315 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) 316 return( ret ); 317 #endif 318 319 ret = entropy_gather_internal( ctx ); 320 321 #if defined(MBEDTLS_THREADING_C) 322 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) 323 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); 324 #endif 325 326 return( ret ); 327 } 328 329 int mbedtls_entropy_func( void *data, unsigned char *output, size_t len ) 330 { 331 int ret, count = 0, i, thresholds_reached; 332 size_t strong_size; 333 mbedtls_entropy_context *ctx = (mbedtls_entropy_context *) data; 334 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE]; 335 336 if( len > MBEDTLS_ENTROPY_BLOCK_SIZE ) 337 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED ); 338 339 #if defined(MBEDTLS_ENTROPY_NV_SEED) 340 /* Update the NV entropy seed before generating any entropy for outside 341 * use. 342 */ 343 if( ctx->initial_entropy_run == 0 ) 344 { 345 ctx->initial_entropy_run = 1; 346 if( ( ret = mbedtls_entropy_update_nv_seed( ctx ) ) != 0 ) 347 return( ret ); 348 } 349 #endif 350 351 #if defined(MBEDTLS_THREADING_C) 352 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) 353 return( ret ); 354 #endif 355 356 /* 357 * Always gather extra entropy before a call 358 */ 359 do 360 { 361 if( count++ > ENTROPY_MAX_LOOP ) 362 { 363 ret = MBEDTLS_ERR_ENTROPY_SOURCE_FAILED; 364 goto exit; 365 } 366 367 if( ( ret = entropy_gather_internal( ctx ) ) != 0 ) 368 goto exit; 369 370 thresholds_reached = 1; 371 strong_size = 0; 372 for( i = 0; i < ctx->source_count; i++ ) 373 { 374 if( ctx->source[i].size < ctx->source[i].threshold ) 375 thresholds_reached = 0; 376 if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG ) 377 strong_size += ctx->source[i].size; 378 } 379 } 380 while( ! thresholds_reached || strong_size < MBEDTLS_ENTROPY_BLOCK_SIZE ); 381 382 memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE ); 383 384 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR) 385 /* 386 * Note that at this stage it is assumed that the accumulator was started 387 * in a previous call to entropy_update(). If this is not guaranteed, the 388 * code below will fail. 389 */ 390 if( ( ret = mbedtls_sha512_finish_ret( &ctx->accumulator, buf ) ) != 0 ) 391 goto exit; 392 393 /* 394 * Reset accumulator and counters and recycle existing entropy 395 */ 396 mbedtls_sha512_free( &ctx->accumulator ); 397 mbedtls_sha512_init( &ctx->accumulator ); 398 if( ( ret = mbedtls_sha512_starts_ret( &ctx->accumulator, 0 ) ) != 0 ) 399 goto exit; 400 if( ( ret = mbedtls_sha512_update_ret( &ctx->accumulator, buf, 401 MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 ) 402 goto exit; 403 404 /* 405 * Perform second SHA-512 on entropy 406 */ 407 if( ( ret = mbedtls_sha512_ret( buf, MBEDTLS_ENTROPY_BLOCK_SIZE, 408 buf, 0 ) ) != 0 ) 409 goto exit; 410 #else /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */ 411 if( ( ret = mbedtls_sha256_finish_ret( &ctx->accumulator, buf ) ) != 0 ) 412 goto exit; 413 414 /* 415 * Reset accumulator and counters and recycle existing entropy 416 */ 417 mbedtls_sha256_free( &ctx->accumulator ); 418 mbedtls_sha256_init( &ctx->accumulator ); 419 if( ( ret = mbedtls_sha256_starts_ret( &ctx->accumulator, 0 ) ) != 0 ) 420 goto exit; 421 if( ( ret = mbedtls_sha256_update_ret( &ctx->accumulator, buf, 422 MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 ) 423 goto exit; 424 425 /* 426 * Perform second SHA-256 on entropy 427 */ 428 if( ( ret = mbedtls_sha256_ret( buf, MBEDTLS_ENTROPY_BLOCK_SIZE, 429 buf, 0 ) ) != 0 ) 430 goto exit; 431 #endif /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */ 432 433 for( i = 0; i < ctx->source_count; i++ ) 434 ctx->source[i].size = 0; 435 436 memcpy( output, buf, len ); 437 438 ret = 0; 439 440 exit: 441 mbedtls_platform_zeroize( buf, sizeof( buf ) ); 442 443 #if defined(MBEDTLS_THREADING_C) 444 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) 445 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); 446 #endif 447 448 return( ret ); 449 } 450 451 #if defined(MBEDTLS_ENTROPY_NV_SEED) 452 int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx ) 453 { 454 int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR; 455 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE]; 456 457 /* Read new seed and write it to NV */ 458 if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 ) 459 return( ret ); 460 461 if( mbedtls_nv_seed_write( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 ) 462 return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR ); 463 464 /* Manually update the remaining stream with a separator value to diverge */ 465 memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE ); 466 ret = mbedtls_entropy_update_manual( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ); 467 468 return( ret ); 469 } 470 #endif /* MBEDTLS_ENTROPY_NV_SEED */ 471 472 #if defined(MBEDTLS_FS_IO) 473 int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path ) 474 { 475 int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR; 476 FILE *f; 477 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE]; 478 479 if( ( f = fopen( path, "wb" ) ) == NULL ) 480 return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR ); 481 482 if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 ) 483 goto exit; 484 485 if( fwrite( buf, 1, MBEDTLS_ENTROPY_BLOCK_SIZE, f ) != MBEDTLS_ENTROPY_BLOCK_SIZE ) 486 { 487 ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR; 488 goto exit; 489 } 490 491 ret = 0; 492 493 exit: 494 mbedtls_platform_zeroize( buf, sizeof( buf ) ); 495 496 fclose( f ); 497 return( ret ); 498 } 499 500 int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path ) 501 { 502 int ret = 0; 503 FILE *f; 504 size_t n; 505 unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ]; 506 507 if( ( f = fopen( path, "rb" ) ) == NULL ) 508 return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR ); 509 510 fseek( f, 0, SEEK_END ); 511 n = (size_t) ftell( f ); 512 fseek( f, 0, SEEK_SET ); 513 514 if( n > MBEDTLS_ENTROPY_MAX_SEED_SIZE ) 515 n = MBEDTLS_ENTROPY_MAX_SEED_SIZE; 516 517 if( fread( buf, 1, n, f ) != n ) 518 ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR; 519 else 520 ret = mbedtls_entropy_update_manual( ctx, buf, n ); 521 522 fclose( f ); 523 524 mbedtls_platform_zeroize( buf, sizeof( buf ) ); 525 526 if( ret != 0 ) 527 return( ret ); 528 529 return( mbedtls_entropy_write_seed_file( ctx, path ) ); 530 } 531 #endif /* MBEDTLS_FS_IO */ 532 533 #if defined(MBEDTLS_SELF_TEST) 534 #if !defined(MBEDTLS_TEST_NULL_ENTROPY) 535 /* 536 * Dummy source function 537 */ 538 static int entropy_dummy_source( void *data, unsigned char *output, 539 size_t len, size_t *olen ) 540 { 541 ((void) data); 542 543 memset( output, 0x2a, len ); 544 *olen = len; 545 546 return( 0 ); 547 } 548 #endif /* !MBEDTLS_TEST_NULL_ENTROPY */ 549 550 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT) 551 552 static int mbedtls_entropy_source_self_test_gather( unsigned char *buf, size_t buf_len ) 553 { 554 int ret = 0; 555 size_t entropy_len = 0; 556 size_t olen = 0; 557 size_t attempts = buf_len; 558 559 while( attempts > 0 && entropy_len < buf_len ) 560 { 561 if( ( ret = mbedtls_hardware_poll( NULL, buf + entropy_len, 562 buf_len - entropy_len, &olen ) ) != 0 ) 563 return( ret ); 564 565 entropy_len += olen; 566 attempts--; 567 } 568 569 if( entropy_len < buf_len ) 570 { 571 ret = 1; 572 } 573 574 return( ret ); 575 } 576 577 578 static int mbedtls_entropy_source_self_test_check_bits( const unsigned char *buf, 579 size_t buf_len ) 580 { 581 unsigned char set= 0xFF; 582 unsigned char unset = 0x00; 583 size_t i; 584 585 for( i = 0; i < buf_len; i++ ) 586 { 587 set &= buf[i]; 588 unset |= buf[i]; 589 } 590 591 return( set == 0xFF || unset == 0x00 ); 592 } 593 594 /* 595 * A test to ensure hat the entropy sources are functioning correctly 596 * and there is no obvious failure. The test performs the following checks: 597 * - The entropy source is not providing only 0s (all bits unset) or 1s (all 598 * bits set). 599 * - The entropy source is not providing values in a pattern. Because the 600 * hardware could be providing data in an arbitrary length, this check polls 601 * the hardware entropy source twice and compares the result to ensure they 602 * are not equal. 603 * - The error code returned by the entropy source is not an error. 604 */ 605 int mbedtls_entropy_source_self_test( int verbose ) 606 { 607 int ret = 0; 608 unsigned char buf0[2 * sizeof( unsigned long long int )]; 609 unsigned char buf1[2 * sizeof( unsigned long long int )]; 610 611 if( verbose != 0 ) 612 mbedtls_printf( " ENTROPY_BIAS test: " ); 613 614 memset( buf0, 0x00, sizeof( buf0 ) ); 615 memset( buf1, 0x00, sizeof( buf1 ) ); 616 617 if( ( ret = mbedtls_entropy_source_self_test_gather( buf0, sizeof( buf0 ) ) ) != 0 ) 618 goto cleanup; 619 if( ( ret = mbedtls_entropy_source_self_test_gather( buf1, sizeof( buf1 ) ) ) != 0 ) 620 goto cleanup; 621 622 /* Make sure that the returned values are not all 0 or 1 */ 623 if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf0, sizeof( buf0 ) ) ) != 0 ) 624 goto cleanup; 625 if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf1, sizeof( buf1 ) ) ) != 0 ) 626 goto cleanup; 627 628 /* Make sure that the entropy source is not returning values in a 629 * pattern */ 630 ret = memcmp( buf0, buf1, sizeof( buf0 ) ) == 0; 631 632 cleanup: 633 if( verbose != 0 ) 634 { 635 if( ret != 0 ) 636 mbedtls_printf( "failed\n" ); 637 else 638 mbedtls_printf( "passed\n" ); 639 640 mbedtls_printf( "\n" ); 641 } 642 643 return( ret != 0 ); 644 } 645 646 #endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */ 647 648 /* 649 * The actual entropy quality is hard to test, but we can at least 650 * test that the functions don't cause errors and write the correct 651 * amount of data to buffers. 652 */ 653 int mbedtls_entropy_self_test( int verbose ) 654 { 655 int ret = 1; 656 #if !defined(MBEDTLS_TEST_NULL_ENTROPY) 657 mbedtls_entropy_context ctx; 658 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 }; 659 unsigned char acc[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 }; 660 size_t i, j; 661 #endif /* !MBEDTLS_TEST_NULL_ENTROPY */ 662 663 if( verbose != 0 ) 664 mbedtls_printf( " ENTROPY test: " ); 665 666 #if !defined(MBEDTLS_TEST_NULL_ENTROPY) 667 mbedtls_entropy_init( &ctx ); 668 669 /* First do a gather to make sure we have default sources */ 670 if( ( ret = mbedtls_entropy_gather( &ctx ) ) != 0 ) 671 goto cleanup; 672 673 ret = mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL, 16, 674 MBEDTLS_ENTROPY_SOURCE_WEAK ); 675 if( ret != 0 ) 676 goto cleanup; 677 678 if( ( ret = mbedtls_entropy_update_manual( &ctx, buf, sizeof buf ) ) != 0 ) 679 goto cleanup; 680 681 /* 682 * To test that mbedtls_entropy_func writes correct number of bytes: 683 * - use the whole buffer and rely on ASan to detect overruns 684 * - collect entropy 8 times and OR the result in an accumulator: 685 * any byte should then be 0 with probably 2^(-64), so requiring 686 * each of the 32 or 64 bytes to be non-zero has a false failure rate 687 * of at most 2^(-58) which is acceptable. 688 */ 689 for( i = 0; i < 8; i++ ) 690 { 691 if( ( ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) ) ) != 0 ) 692 goto cleanup; 693 694 for( j = 0; j < sizeof( buf ); j++ ) 695 acc[j] |= buf[j]; 696 } 697 698 for( j = 0; j < sizeof( buf ); j++ ) 699 { 700 if( acc[j] == 0 ) 701 { 702 ret = 1; 703 goto cleanup; 704 } 705 } 706 707 #if defined(MBEDTLS_ENTROPY_HARDWARE_ALT) 708 if( ( ret = mbedtls_entropy_source_self_test( 0 ) ) != 0 ) 709 goto cleanup; 710 #endif 711 712 cleanup: 713 mbedtls_entropy_free( &ctx ); 714 #endif /* !MBEDTLS_TEST_NULL_ENTROPY */ 715 716 if( verbose != 0 ) 717 { 718 if( ret != 0 ) 719 mbedtls_printf( "failed\n" ); 720 else 721 mbedtls_printf( "passed\n" ); 722 723 mbedtls_printf( "\n" ); 724 } 725 726 return( ret != 0 ); 727 } 728 #endif /* MBEDTLS_SELF_TEST */ 729 730 #endif /* MBEDTLS_ENTROPY_C */ 731