source: azure_iot_hub_mbedtls/trunk/mbedtls-2.16.1/library/entropy.c@ 398

Last change on this file since 398 was 398, checked in by coas-nagasima, 5 years ago

mbedTLS版Azure IoT Hub接続サンプルのソースコードを追加
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1/*
2 * Entropy accumulator implementation
3 *
4 * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
5 * SPDX-License-Identifier: Apache-2.0
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
40#include <string.h>
41
42#if defined(MBEDTLS_FS_IO)
43#include <stdio.h>
44#endif
45
46#if defined(MBEDTLS_ENTROPY_NV_SEED)
47#include "mbedtls/platform.h"
48#endif
49
50#if defined(MBEDTLS_SELF_TEST)
51#if defined(MBEDTLS_PLATFORM_C)
52#include "mbedtls/platform.h"
53#else
54#include <stdio.h>
55#define mbedtls_printf printf
56#endif /* MBEDTLS_PLATFORM_C */
57#endif /* MBEDTLS_SELF_TEST */
58
59#if defined(MBEDTLS_HAVEGE_C)
60#include "mbedtls/havege.h"
61#endif
62
63#define ENTROPY_MAX_LOOP 256 /**< Maximum amount to loop before error */
64
65void mbedtls_entropy_init( mbedtls_entropy_context *ctx )
66{
67 ctx->source_count = 0;
68 memset( ctx->source, 0, sizeof( ctx->source ) );
69
70#if defined(MBEDTLS_THREADING_C)
71 mbedtls_mutex_init( &ctx->mutex );
72#endif
73
74 ctx->accumulator_started = 0;
75#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
76 mbedtls_sha512_init( &ctx->accumulator );
77#else
78 mbedtls_sha256_init( &ctx->accumulator );
79#endif
80#if defined(MBEDTLS_HAVEGE_C)
81 mbedtls_havege_init( &ctx->havege_data );
82#endif
83
84 /* Reminder: Update ENTROPY_HAVE_STRONG in the test files
85 * when adding more strong entropy sources here. */
86
87#if defined(MBEDTLS_TEST_NULL_ENTROPY)
88 mbedtls_entropy_add_source( ctx, mbedtls_null_entropy_poll, NULL,
89 1, MBEDTLS_ENTROPY_SOURCE_STRONG );
90#endif
91
92#if !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES)
93#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
94 mbedtls_entropy_add_source( ctx, mbedtls_platform_entropy_poll, NULL,
95 MBEDTLS_ENTROPY_MIN_PLATFORM,
96 MBEDTLS_ENTROPY_SOURCE_STRONG );
97#endif
98#if defined(MBEDTLS_TIMING_C)
99 mbedtls_entropy_add_source( ctx, mbedtls_hardclock_poll, NULL,
100 MBEDTLS_ENTROPY_MIN_HARDCLOCK,
101 MBEDTLS_ENTROPY_SOURCE_WEAK );
102#endif
103#if defined(MBEDTLS_HAVEGE_C)
104 mbedtls_entropy_add_source( ctx, mbedtls_havege_poll, &ctx->havege_data,
105 MBEDTLS_ENTROPY_MIN_HAVEGE,
106 MBEDTLS_ENTROPY_SOURCE_STRONG );
107#endif
108#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
109 mbedtls_entropy_add_source( ctx, mbedtls_hardware_poll, NULL,
110 MBEDTLS_ENTROPY_MIN_HARDWARE,
111 MBEDTLS_ENTROPY_SOURCE_STRONG );
112#endif
113#if defined(MBEDTLS_ENTROPY_NV_SEED)
114 mbedtls_entropy_add_source( ctx, mbedtls_nv_seed_poll, NULL,
115 MBEDTLS_ENTROPY_BLOCK_SIZE,
116 MBEDTLS_ENTROPY_SOURCE_STRONG );
117 ctx->initial_entropy_run = 0;
118#endif
119#endif /* MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES */
120}
121
122void 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#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
131 mbedtls_sha512_free( &ctx->accumulator );
132#else
133 mbedtls_sha256_free( &ctx->accumulator );
134#endif
135#if defined(MBEDTLS_ENTROPY_NV_SEED)
136 ctx->initial_entropy_run = 0;
137#endif
138 ctx->source_count = 0;
139 mbedtls_platform_zeroize( ctx->source, sizeof( ctx->source ) );
140 ctx->accumulator_started = 0;
141}
142
143int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,
144 mbedtls_entropy_f_source_ptr f_source, void *p_source,
145 size_t threshold, int strong )
146{
147 int idx, ret = 0;
148
149#if defined(MBEDTLS_THREADING_C)
150 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
151 return( ret );
152#endif
153
154 idx = ctx->source_count;
155 if( idx >= MBEDTLS_ENTROPY_MAX_SOURCES )
156 {
157 ret = MBEDTLS_ERR_ENTROPY_MAX_SOURCES;
158 goto exit;
159 }
160
161 ctx->source[idx].f_source = f_source;
162 ctx->source[idx].p_source = p_source;
163 ctx->source[idx].threshold = threshold;
164 ctx->source[idx].strong = strong;
165
166 ctx->source_count++;
167
168exit:
169#if defined(MBEDTLS_THREADING_C)
170 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
171 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
172#endif
173
174 return( ret );
175}
176
177/*
178 * Entropy accumulator update
179 */
180static int entropy_update( mbedtls_entropy_context *ctx, unsigned char source_id,
181 const unsigned char *data, size_t len )
182{
183 unsigned char header[2];
184 unsigned char tmp[MBEDTLS_ENTROPY_BLOCK_SIZE];
185 size_t use_len = len;
186 const unsigned char *p = data;
187 int ret = 0;
188
189 if( use_len > MBEDTLS_ENTROPY_BLOCK_SIZE )
190 {
191#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
192 if( ( ret = mbedtls_sha512_ret( data, len, tmp, 0 ) ) != 0 )
193 goto cleanup;
194#else
195 if( ( ret = mbedtls_sha256_ret( data, len, tmp, 0 ) ) != 0 )
196 goto cleanup;
197#endif
198 p = tmp;
199 use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
200 }
201
202 header[0] = source_id;
203 header[1] = use_len & 0xFF;
204
205 /*
206 * Start the accumulator if this has not already happened. Note that
207 * it is sufficient to start the accumulator here only because all calls to
208 * gather entropy eventually execute this code.
209 */
210#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
211 if( ctx->accumulator_started == 0 &&
212 ( ret = mbedtls_sha512_starts_ret( &ctx->accumulator, 0 ) ) != 0 )
213 goto cleanup;
214 else
215 ctx->accumulator_started = 1;
216 if( ( ret = mbedtls_sha512_update_ret( &ctx->accumulator, header, 2 ) ) != 0 )
217 goto cleanup;
218 ret = mbedtls_sha512_update_ret( &ctx->accumulator, p, use_len );
219#else
220 if( ctx->accumulator_started == 0 &&
221 ( ret = mbedtls_sha256_starts_ret( &ctx->accumulator, 0 ) ) != 0 )
222 goto cleanup;
223 else
224 ctx->accumulator_started = 1;
225 if( ( ret = mbedtls_sha256_update_ret( &ctx->accumulator, header, 2 ) ) != 0 )
226 goto cleanup;
227 ret = mbedtls_sha256_update_ret( &ctx->accumulator, p, use_len );
228#endif
229
230cleanup:
231 mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
232
233 return( ret );
234}
235
236int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx,
237 const unsigned char *data, size_t len )
238{
239 int ret;
240
241#if defined(MBEDTLS_THREADING_C)
242 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
243 return( ret );
244#endif
245
246 ret = entropy_update( ctx, MBEDTLS_ENTROPY_SOURCE_MANUAL, data, len );
247
248#if defined(MBEDTLS_THREADING_C)
249 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
250 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
251#endif
252
253 return( ret );
254}
255
256/*
257 * Run through the different sources to add entropy to our accumulator
258 */
259static int entropy_gather_internal( mbedtls_entropy_context *ctx )
260{
261 int ret, i, have_one_strong = 0;
262 unsigned char buf[MBEDTLS_ENTROPY_MAX_GATHER];
263 size_t olen;
264
265 if( ctx->source_count == 0 )
266 return( MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED );
267
268 /*
269 * Run through our entropy sources
270 */
271 for( i = 0; i < ctx->source_count; i++ )
272 {
273 if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG )
274 have_one_strong = 1;
275
276 olen = 0;
277 if( ( ret = ctx->source[i].f_source( ctx->source[i].p_source,
278 buf, MBEDTLS_ENTROPY_MAX_GATHER, &olen ) ) != 0 )
279 {
280 goto cleanup;
281 }
282
283 /*
284 * Add if we actually gathered something
285 */
286 if( olen > 0 )
287 {
288 if( ( ret = entropy_update( ctx, (unsigned char) i,
289 buf, olen ) ) != 0 )
290 return( ret );
291 ctx->source[i].size += olen;
292 }
293 }
294
295 if( have_one_strong == 0 )
296 ret = MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE;
297
298cleanup:
299 mbedtls_platform_zeroize( buf, sizeof( buf ) );
300
301 return( ret );
302}
303
304/*
305 * Thread-safe wrapper for entropy_gather_internal()
306 */
307int mbedtls_entropy_gather( mbedtls_entropy_context *ctx )
308{
309 int ret;
310
311#if defined(MBEDTLS_THREADING_C)
312 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
313 return( ret );
314#endif
315
316 ret = entropy_gather_internal( ctx );
317
318#if defined(MBEDTLS_THREADING_C)
319 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
320 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
321#endif
322
323 return( ret );
324}
325
326int mbedtls_entropy_func( void *data, unsigned char *output, size_t len )
327{
328 int ret, count = 0, i, done;
329 mbedtls_entropy_context *ctx = (mbedtls_entropy_context *) data;
330 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
331
332 if( len > MBEDTLS_ENTROPY_BLOCK_SIZE )
333 return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
334
335#if defined(MBEDTLS_ENTROPY_NV_SEED)
336 /* Update the NV entropy seed before generating any entropy for outside
337 * use.
338 */
339 if( ctx->initial_entropy_run == 0 )
340 {
341 ctx->initial_entropy_run = 1;
342 if( ( ret = mbedtls_entropy_update_nv_seed( ctx ) ) != 0 )
343 return( ret );
344 }
345#endif
346
347#if defined(MBEDTLS_THREADING_C)
348 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
349 return( ret );
350#endif
351
352 /*
353 * Always gather extra entropy before a call
354 */
355 do
356 {
357 if( count++ > ENTROPY_MAX_LOOP )
358 {
359 ret = MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
360 goto exit;
361 }
362
363 if( ( ret = entropy_gather_internal( ctx ) ) != 0 )
364 goto exit;
365
366 done = 1;
367 for( i = 0; i < ctx->source_count; i++ )
368 if( ctx->source[i].size < ctx->source[i].threshold )
369 done = 0;
370 }
371 while( ! done );
372
373 memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
374
375#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
376 /*
377 * Note that at this stage it is assumed that the accumulator was started
378 * in a previous call to entropy_update(). If this is not guaranteed, the
379 * code below will fail.
380 */
381 if( ( ret = mbedtls_sha512_finish_ret( &ctx->accumulator, buf ) ) != 0 )
382 goto exit;
383
384 /*
385 * Reset accumulator and counters and recycle existing entropy
386 */
387 mbedtls_sha512_free( &ctx->accumulator );
388 mbedtls_sha512_init( &ctx->accumulator );
389 if( ( ret = mbedtls_sha512_starts_ret( &ctx->accumulator, 0 ) ) != 0 )
390 goto exit;
391 if( ( ret = mbedtls_sha512_update_ret( &ctx->accumulator, buf,
392 MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
393 goto exit;
394
395 /*
396 * Perform second SHA-512 on entropy
397 */
398 if( ( ret = mbedtls_sha512_ret( buf, MBEDTLS_ENTROPY_BLOCK_SIZE,
399 buf, 0 ) ) != 0 )
400 goto exit;
401#else /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
402 if( ( ret = mbedtls_sha256_finish_ret( &ctx->accumulator, buf ) ) != 0 )
403 goto exit;
404
405 /*
406 * Reset accumulator and counters and recycle existing entropy
407 */
408 mbedtls_sha256_free( &ctx->accumulator );
409 mbedtls_sha256_init( &ctx->accumulator );
410 if( ( ret = mbedtls_sha256_starts_ret( &ctx->accumulator, 0 ) ) != 0 )
411 goto exit;
412 if( ( ret = mbedtls_sha256_update_ret( &ctx->accumulator, buf,
413 MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
414 goto exit;
415
416 /*
417 * Perform second SHA-256 on entropy
418 */
419 if( ( ret = mbedtls_sha256_ret( buf, MBEDTLS_ENTROPY_BLOCK_SIZE,
420 buf, 0 ) ) != 0 )
421 goto exit;
422#endif /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
423
424 for( i = 0; i < ctx->source_count; i++ )
425 ctx->source[i].size = 0;
426
427 memcpy( output, buf, len );
428
429 ret = 0;
430
431exit:
432 mbedtls_platform_zeroize( buf, sizeof( buf ) );
433
434#if defined(MBEDTLS_THREADING_C)
435 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
436 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
437#endif
438
439 return( ret );
440}
441
442#if defined(MBEDTLS_ENTROPY_NV_SEED)
443int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx )
444{
445 int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
446 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
447
448 /* Read new seed and write it to NV */
449 if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
450 return( ret );
451
452 if( mbedtls_nv_seed_write( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 )
453 return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
454
455 /* Manually update the remaining stream with a separator value to diverge */
456 memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
457 ret = mbedtls_entropy_update_manual( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
458
459 return( ret );
460}
461#endif /* MBEDTLS_ENTROPY_NV_SEED */
462
463#if defined(MBEDTLS_FS_IO)
464int mbedtls_entropy_write_seed_file( mbedtls_entropy_context *ctx, const char *path )
465{
466 int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
467 FILE *f;
468 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
469
470 if( ( f = fopen( path, "wb" ) ) == NULL )
471 return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
472
473 if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
474 goto exit;
475
476 if( fwrite( buf, 1, MBEDTLS_ENTROPY_BLOCK_SIZE, f ) != MBEDTLS_ENTROPY_BLOCK_SIZE )
477 {
478 ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
479 goto exit;
480 }
481
482 ret = 0;
483
484exit:
485 mbedtls_platform_zeroize( buf, sizeof( buf ) );
486
487 fclose( f );
488 return( ret );
489}
490
491int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path )
492{
493 int ret = 0;
494 FILE *f;
495 size_t n;
496 unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ];
497
498 if( ( f = fopen( path, "rb" ) ) == NULL )
499 return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
500
501 fseek( f, 0, SEEK_END );
502 n = (size_t) ftell( f );
503 fseek( f, 0, SEEK_SET );
504
505 if( n > MBEDTLS_ENTROPY_MAX_SEED_SIZE )
506 n = MBEDTLS_ENTROPY_MAX_SEED_SIZE;
507
508 if( fread( buf, 1, n, f ) != n )
509 ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
510 else
511 ret = mbedtls_entropy_update_manual( ctx, buf, n );
512
513 fclose( f );
514
515 mbedtls_platform_zeroize( buf, sizeof( buf ) );
516
517 if( ret != 0 )
518 return( ret );
519
520 return( mbedtls_entropy_write_seed_file( ctx, path ) );
521}
522#endif /* MBEDTLS_FS_IO */
523
524#if defined(MBEDTLS_SELF_TEST)
525#if !defined(MBEDTLS_TEST_NULL_ENTROPY)
526/*
527 * Dummy source function
528 */
529static int entropy_dummy_source( void *data, unsigned char *output,
530 size_t len, size_t *olen )
531{
532 ((void) data);
533
534 memset( output, 0x2a, len );
535 *olen = len;
536
537 return( 0 );
538}
539#endif /* !MBEDTLS_TEST_NULL_ENTROPY */
540
541#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
542
543static int mbedtls_entropy_source_self_test_gather( unsigned char *buf, size_t buf_len )
544{
545 int ret = 0;
546 size_t entropy_len = 0;
547 size_t olen = 0;
548 size_t attempts = buf_len;
549
550 while( attempts > 0 && entropy_len < buf_len )
551 {
552 if( ( ret = mbedtls_hardware_poll( NULL, buf + entropy_len,
553 buf_len - entropy_len, &olen ) ) != 0 )
554 return( ret );
555
556 entropy_len += olen;
557 attempts--;
558 }
559
560 if( entropy_len < buf_len )
561 {
562 ret = 1;
563 }
564
565 return( ret );
566}
567
568
569static int mbedtls_entropy_source_self_test_check_bits( const unsigned char *buf,
570 size_t buf_len )
571{
572 unsigned char set= 0xFF;
573 unsigned char unset = 0x00;
574 size_t i;
575
576 for( i = 0; i < buf_len; i++ )
577 {
578 set &= buf[i];
579 unset |= buf[i];
580 }
581
582 return( set == 0xFF || unset == 0x00 );
583}
584
585/*
586 * A test to ensure hat the entropy sources are functioning correctly
587 * and there is no obvious failure. The test performs the following checks:
588 * - The entropy source is not providing only 0s (all bits unset) or 1s (all
589 * bits set).
590 * - The entropy source is not providing values in a pattern. Because the
591 * hardware could be providing data in an arbitrary length, this check polls
592 * the hardware entropy source twice and compares the result to ensure they
593 * are not equal.
594 * - The error code returned by the entropy source is not an error.
595 */
596int mbedtls_entropy_source_self_test( int verbose )
597{
598 int ret = 0;
599 unsigned char buf0[2 * sizeof( unsigned long long int )];
600 unsigned char buf1[2 * sizeof( unsigned long long int )];
601
602 if( verbose != 0 )
603 mbedtls_printf( " ENTROPY_BIAS test: " );
604
605 memset( buf0, 0x00, sizeof( buf0 ) );
606 memset( buf1, 0x00, sizeof( buf1 ) );
607
608 if( ( ret = mbedtls_entropy_source_self_test_gather( buf0, sizeof( buf0 ) ) ) != 0 )
609 goto cleanup;
610 if( ( ret = mbedtls_entropy_source_self_test_gather( buf1, sizeof( buf1 ) ) ) != 0 )
611 goto cleanup;
612
613 /* Make sure that the returned values are not all 0 or 1 */
614 if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf0, sizeof( buf0 ) ) ) != 0 )
615 goto cleanup;
616 if( ( ret = mbedtls_entropy_source_self_test_check_bits( buf1, sizeof( buf1 ) ) ) != 0 )
617 goto cleanup;
618
619 /* Make sure that the entropy source is not returning values in a
620 * pattern */
621 ret = memcmp( buf0, buf1, sizeof( buf0 ) ) == 0;
622
623cleanup:
624 if( verbose != 0 )
625 {
626 if( ret != 0 )
627 mbedtls_printf( "failed\n" );
628 else
629 mbedtls_printf( "passed\n" );
630
631 mbedtls_printf( "\n" );
632 }
633
634 return( ret != 0 );
635}
636
637#endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */
638
639/*
640 * The actual entropy quality is hard to test, but we can at least
641 * test that the functions don't cause errors and write the correct
642 * amount of data to buffers.
643 */
644int mbedtls_entropy_self_test( int verbose )
645{
646 int ret = 1;
647#if !defined(MBEDTLS_TEST_NULL_ENTROPY)
648 mbedtls_entropy_context ctx;
649 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
650 unsigned char acc[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
651 size_t i, j;
652#endif /* !MBEDTLS_TEST_NULL_ENTROPY */
653
654 if( verbose != 0 )
655 mbedtls_printf( " ENTROPY test: " );
656
657#if !defined(MBEDTLS_TEST_NULL_ENTROPY)
658 mbedtls_entropy_init( &ctx );
659
660 /* First do a gather to make sure we have default sources */
661 if( ( ret = mbedtls_entropy_gather( &ctx ) ) != 0 )
662 goto cleanup;
663
664 ret = mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL, 16,
665 MBEDTLS_ENTROPY_SOURCE_WEAK );
666 if( ret != 0 )
667 goto cleanup;
668
669 if( ( ret = mbedtls_entropy_update_manual( &ctx, buf, sizeof buf ) ) != 0 )
670 goto cleanup;
671
672 /*
673 * To test that mbedtls_entropy_func writes correct number of bytes:
674 * - use the whole buffer and rely on ASan to detect overruns
675 * - collect entropy 8 times and OR the result in an accumulator:
676 * any byte should then be 0 with probably 2^(-64), so requiring
677 * each of the 32 or 64 bytes to be non-zero has a false failure rate
678 * of at most 2^(-58) which is acceptable.
679 */
680 for( i = 0; i < 8; i++ )
681 {
682 if( ( ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) ) ) != 0 )
683 goto cleanup;
684
685 for( j = 0; j < sizeof( buf ); j++ )
686 acc[j] |= buf[j];
687 }
688
689 for( j = 0; j < sizeof( buf ); j++ )
690 {
691 if( acc[j] == 0 )
692 {
693 ret = 1;
694 goto cleanup;
695 }
696 }
697
698#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
699 if( ( ret = mbedtls_entropy_source_self_test( 0 ) ) != 0 )
700 goto cleanup;
701#endif
702
703cleanup:
704 mbedtls_entropy_free( &ctx );
705#endif /* !MBEDTLS_TEST_NULL_ENTROPY */
706
707 if( verbose != 0 )
708 {
709 if( ret != 0 )
710 mbedtls_printf( "failed\n" );
711 else
712 mbedtls_printf( "passed\n" );
713
714 mbedtls_printf( "\n" );
715 }
716
717 return( ret != 0 );
718}
719#endif /* MBEDTLS_SELF_TEST */
720
721#endif /* MBEDTLS_ENTROPY_C */
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