1/*
2 * Entropy accumulator implementation
3 *
4 * Copyright The Mbed TLS Contributors
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
20#include "common.h"
21
22#if defined(MBEDTLS_ENTROPY_C)
23
24#if defined(MBEDTLS_TEST_NULL_ENTROPY)
25#warning "**** WARNING! MBEDTLS_TEST_NULL_ENTROPY defined! "
26#warning "**** THIS BUILD HAS NO DEFINED ENTROPY SOURCES "
27#warning "**** THIS BUILD IS *NOT* SUITABLE FOR PRODUCTION USE "
28#endif
29
30#include "mbedtls/entropy.h"
31#include "mbedtls/entropy_poll.h"
32#include "mbedtls/platform_util.h"
33#include "mbedtls/error.h"
34#include "mbedtls/sha256.h"
35#include "mbedtls/sha512.h"
36
37#include <string.h>
38
39#if defined(MBEDTLS_FS_IO)
40#include <stdio.h>
41#endif
42
43#include "mbedtls/platform.h"
44
45#include "mbedtls/platform.h"
46
47#if defined(MBEDTLS_HAVEGE_C)
48#include "mbedtls/havege.h"
49#endif
50
51#define ENTROPY_MAX_LOOP 256 /**< Maximum amount to loop before error */
52
53void mbedtls_entropy_init(mbedtls_entropy_context *ctx)
54{
55 ctx->source_count = 0;
56 memset(ctx->source, 0, sizeof(ctx->source));
57
58#if defined(MBEDTLS_THREADING_C)
59 mbedtls_mutex_init(&ctx->mutex);
60#endif
61
62 ctx->accumulator_started = 0;
63#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
64 mbedtls_sha512_init(&ctx->accumulator);
65#else
66 mbedtls_sha256_init(&ctx->accumulator);
67#endif
68#if defined(MBEDTLS_HAVEGE_C)
69 mbedtls_havege_init(&ctx->havege_data);
70#endif
71
72 /* Reminder: Update ENTROPY_HAVE_STRONG in the test files
73 * when adding more strong entropy sources here. */
74
75#if defined(MBEDTLS_TEST_NULL_ENTROPY)
76 mbedtls_entropy_add_source(ctx, mbedtls_null_entropy_poll, NULL,
77 1, MBEDTLS_ENTROPY_SOURCE_STRONG);
78#endif
79
80#if !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES)
81#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
82 mbedtls_entropy_add_source(ctx, mbedtls_platform_entropy_poll, NULL,
83 MBEDTLS_ENTROPY_MIN_PLATFORM,
84 MBEDTLS_ENTROPY_SOURCE_STRONG);
85#endif
86#if defined(MBEDTLS_TIMING_C)
87 mbedtls_entropy_add_source(ctx, mbedtls_hardclock_poll, NULL,
88 MBEDTLS_ENTROPY_MIN_HARDCLOCK,
89 MBEDTLS_ENTROPY_SOURCE_WEAK);
90#endif
91#if defined(MBEDTLS_HAVEGE_C)
92 mbedtls_entropy_add_source(ctx, mbedtls_havege_poll, &ctx->havege_data,
93 MBEDTLS_ENTROPY_MIN_HAVEGE,
94 MBEDTLS_ENTROPY_SOURCE_STRONG);
95#endif
96#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
97 mbedtls_entropy_add_source(ctx, mbedtls_hardware_poll, NULL,
98 MBEDTLS_ENTROPY_MIN_HARDWARE,
99 MBEDTLS_ENTROPY_SOURCE_STRONG);
100#endif
101#if defined(MBEDTLS_ENTROPY_NV_SEED)
102 mbedtls_entropy_add_source(ctx, mbedtls_nv_seed_poll, NULL,
103 MBEDTLS_ENTROPY_BLOCK_SIZE,
104 MBEDTLS_ENTROPY_SOURCE_STRONG);
105 ctx->initial_entropy_run = 0;
106#endif
107#endif /* MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES */
108}
109
110void mbedtls_entropy_free(mbedtls_entropy_context *ctx)
111{
112 /* If the context was already free, don't call free() again.
113 * This is important for mutexes which don't allow double-free. */
114 if (ctx->accumulator_started == -1) {
115 return;
116 }
117
118#if defined(MBEDTLS_HAVEGE_C)
119 mbedtls_havege_free(&ctx->havege_data);
120#endif
121#if defined(MBEDTLS_THREADING_C)
122 mbedtls_mutex_free(&ctx->mutex);
123#endif
124#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
125 mbedtls_sha512_free(&ctx->accumulator);
126#else
127 mbedtls_sha256_free(&ctx->accumulator);
128#endif
129#if defined(MBEDTLS_ENTROPY_NV_SEED)
130 ctx->initial_entropy_run = 0;
131#endif
132 ctx->source_count = 0;
133 mbedtls_platform_zeroize(ctx->source, sizeof(ctx->source));
134 ctx->accumulator_started = -1;
135}
136
137int mbedtls_entropy_add_source(mbedtls_entropy_context *ctx,
138 mbedtls_entropy_f_source_ptr f_source, void *p_source,
139 size_t threshold, int strong)
140{
141 int idx, ret = 0;
142
143#if defined(MBEDTLS_THREADING_C)
144 if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
145 return ret;
146 }
147#endif
148
149 idx = ctx->source_count;
150 if (idx >= MBEDTLS_ENTROPY_MAX_SOURCES) {
151 ret = MBEDTLS_ERR_ENTROPY_MAX_SOURCES;
152 goto exit;
153 }
154
155 ctx->source[idx].f_source = f_source;
156 ctx->source[idx].p_source = p_source;
157 ctx->source[idx].threshold = threshold;
158 ctx->source[idx].strong = strong;
159
160 ctx->source_count++;
161
162exit:
163#if defined(MBEDTLS_THREADING_C)
164 if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
165 return MBEDTLS_ERR_THREADING_MUTEX_ERROR;
166 }
167#endif
168
169 return ret;
170}
171
172/*
173 * Entropy accumulator update
174 */
175static int entropy_update(mbedtls_entropy_context *ctx, unsigned char source_id,
176 const unsigned char *data, size_t len)
177{
178 unsigned char header[2];
179 unsigned char tmp[MBEDTLS_ENTROPY_BLOCK_SIZE];
180 size_t use_len = len;
181 const unsigned char *p = data;
182 int ret = 0;
183
184 if (use_len > MBEDTLS_ENTROPY_BLOCK_SIZE) {
185#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
186 if ((ret = mbedtls_sha512_ret(data, len, tmp, 0)) != 0) {
187 goto cleanup;
188 }
189#else
190 if ((ret = mbedtls_sha256_ret(data, len, tmp, 0)) != 0) {
191 goto cleanup;
192 }
193#endif
194 p = tmp;
195 use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
196 }
197
198 header[0] = source_id;
199 header[1] = use_len & 0xFF;
200
201 /*
202 * Start the accumulator if this has not already happened. Note that
203 * it is sufficient to start the accumulator here only because all calls to
204 * gather entropy eventually execute this code.
205 */
206#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
207 if (ctx->accumulator_started == 0 &&
208 (ret = mbedtls_sha512_starts_ret(&ctx->accumulator, 0)) != 0) {
209 goto cleanup;
210 } else {
211 ctx->accumulator_started = 1;
212 }
213 if ((ret = mbedtls_sha512_update_ret(&ctx->accumulator, header, 2)) != 0) {
214 goto cleanup;
215 }
216 ret = mbedtls_sha512_update_ret(&ctx->accumulator, p, use_len);
217#else
218 if (ctx->accumulator_started == 0 &&
219 (ret = mbedtls_sha256_starts_ret(&ctx->accumulator, 0)) != 0) {
220 goto cleanup;
221 } else {
222 ctx->accumulator_started = 1;
223 }
224 if ((ret = mbedtls_sha256_update_ret(&ctx->accumulator, header, 2)) != 0) {
225 goto cleanup;
226 }
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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
240
241#if defined(MBEDTLS_THREADING_C)
242 if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
243 return ret;
244 }
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 }
253#endif
254
255 return ret;
256}
257
258/*
259 * Run through the different sources to add entropy to our accumulator
260 */
261static int entropy_gather_internal(mbedtls_entropy_context *ctx)
262{
263 int ret = MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
264 int i;
265 int have_one_strong = 0;
266 unsigned char buf[MBEDTLS_ENTROPY_MAX_GATHER];
267 size_t olen;
268
269 if (ctx->source_count == 0) {
270 return MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED;
271 }
272
273 /*
274 * Run through our entropy sources
275 */
276 for (i = 0; i < ctx->source_count; i++) {
277 if (ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG) {
278 have_one_strong = 1;
279 }
280
281 olen = 0;
282 if ((ret = ctx->source[i].f_source(ctx->source[i].p_source,
283 buf, MBEDTLS_ENTROPY_MAX_GATHER, &olen)) != 0) {
284 goto cleanup;
285 }
286
287 /*
288 * Add if we actually gathered something
289 */
290 if (olen > 0) {
291 if ((ret = entropy_update(ctx, (unsigned char) i,
292 buf, olen)) != 0) {
293 return ret;
294 }
295 ctx->source[i].size += olen;
296 }
297 }
298
299 if (have_one_strong == 0) {
300 ret = MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE;
301 }
302
303cleanup:
304 mbedtls_platform_zeroize(buf, sizeof(buf));
305
306 return ret;
307}
308
309/*
310 * Thread-safe wrapper for entropy_gather_internal()
311 */
312int mbedtls_entropy_gather(mbedtls_entropy_context *ctx)
313{
314 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
315
316#if defined(MBEDTLS_THREADING_C)
317 if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
318 return ret;
319 }
320#endif
321
322 ret = entropy_gather_internal(ctx);
323
324#if defined(MBEDTLS_THREADING_C)
325 if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
326 return MBEDTLS_ERR_THREADING_MUTEX_ERROR;
327 }
328#endif
329
330 return ret;
331}
332
333int mbedtls_entropy_func(void *data, unsigned char *output, size_t len)
334{
335 int ret, count = 0, i, thresholds_reached;
336 size_t strong_size;
337 mbedtls_entropy_context *ctx = (mbedtls_entropy_context *) data;
338 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
339
340 if (len > MBEDTLS_ENTROPY_BLOCK_SIZE) {
341 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
342 }
343
344#if defined(MBEDTLS_ENTROPY_NV_SEED)
345 /* Update the NV entropy seed before generating any entropy for outside
346 * use.
347 */
348 if (ctx->initial_entropy_run == 0) {
349 ctx->initial_entropy_run = 1;
350 if ((ret = mbedtls_entropy_update_nv_seed(ctx)) != 0) {
351 return ret;
352 }
353 }
354#endif
355
356#if defined(MBEDTLS_THREADING_C)
357 if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
358 return ret;
359 }
360#endif
361
362 /*
363 * Always gather extra entropy before a call
364 */
365 do {
366 if (count++ > ENTROPY_MAX_LOOP) {
367 ret = MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
368 goto exit;
369 }
370
371 if ((ret = entropy_gather_internal(ctx)) != 0) {
372 goto exit;
373 }
374
375 thresholds_reached = 1;
376 strong_size = 0;
377 for (i = 0; i < ctx->source_count; i++) {
378 if (ctx->source[i].size < ctx->source[i].threshold) {
379 thresholds_reached = 0;
380 }
381 if (ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG) {
382 strong_size += ctx->source[i].size;
383 }
384 }
385 } while (!thresholds_reached || strong_size < MBEDTLS_ENTROPY_BLOCK_SIZE);
386
387 memset(buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE);
388
389#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
390 /*
391 * Note that at this stage it is assumed that the accumulator was started
392 * in a previous call to entropy_update(). If this is not guaranteed, the
393 * code below will fail.
394 */
395 if ((ret = mbedtls_sha512_finish_ret(&ctx->accumulator, buf)) != 0) {
396 goto exit;
397 }
398
399 /*
400 * Reset accumulator and counters and recycle existing entropy
401 */
402 mbedtls_sha512_free(&ctx->accumulator);
403 mbedtls_sha512_init(&ctx->accumulator);
404 if ((ret = mbedtls_sha512_starts_ret(&ctx->accumulator, 0)) != 0) {
405 goto exit;
406 }
407 if ((ret = mbedtls_sha512_update_ret(&ctx->accumulator, buf,
408 MBEDTLS_ENTROPY_BLOCK_SIZE)) != 0) {
409 goto exit;
410 }
411
412 /*
413 * Perform second SHA-512 on entropy
414 */
415 if ((ret = mbedtls_sha512_ret(buf, MBEDTLS_ENTROPY_BLOCK_SIZE,
416 buf, 0)) != 0) {
417 goto exit;
418 }
419#else /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
420 if ((ret = mbedtls_sha256_finish_ret(&ctx->accumulator, buf)) != 0) {
421 goto exit;
422 }
423
424 /*
425 * Reset accumulator and counters and recycle existing entropy
426 */
427 mbedtls_sha256_free(&ctx->accumulator);
428 mbedtls_sha256_init(&ctx->accumulator);
429 if ((ret = mbedtls_sha256_starts_ret(&ctx->accumulator, 0)) != 0) {
430 goto exit;
431 }
432 if ((ret = mbedtls_sha256_update_ret(&ctx->accumulator, buf,
433 MBEDTLS_ENTROPY_BLOCK_SIZE)) != 0) {
434 goto exit;
435 }
436
437 /*
438 * Perform second SHA-256 on entropy
439 */
440 if ((ret = mbedtls_sha256_ret(buf, MBEDTLS_ENTROPY_BLOCK_SIZE,
441 buf, 0)) != 0) {
442 goto exit;
443 }
444#endif /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
445
446 for (i = 0; i < ctx->source_count; i++) {
447 ctx->source[i].size = 0;
448 }
449
450 memcpy(output, buf, len);
451
452 ret = 0;
453
454exit:
455 mbedtls_platform_zeroize(buf, sizeof(buf));
456
457#if defined(MBEDTLS_THREADING_C)
458 if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
459 return MBEDTLS_ERR_THREADING_MUTEX_ERROR;
460 }
461#endif
462
463 return ret;
464}
465
466#if defined(MBEDTLS_ENTROPY_NV_SEED)
467int mbedtls_entropy_update_nv_seed(mbedtls_entropy_context *ctx)
468{
469 int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
470 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
471
472 /* Read new seed and write it to NV */
473 if ((ret = mbedtls_entropy_func(ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE)) != 0) {
474 return ret;
475 }
476
477 if (mbedtls_nv_seed_write(buf, MBEDTLS_ENTROPY_BLOCK_SIZE) < 0) {
478 return MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
479 }
480
481 /* Manually update the remaining stream with a separator value to diverge */
482 memset(buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE);
483 ret = mbedtls_entropy_update_manual(ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE);
484
485 return ret;
486}
487#endif /* MBEDTLS_ENTROPY_NV_SEED */
488
489#if defined(MBEDTLS_FS_IO)
490int mbedtls_entropy_write_seed_file(mbedtls_entropy_context *ctx, const char *path)
491{
492 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
493 FILE *f = NULL;
494 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
495
496 if ((ret = mbedtls_entropy_func(ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE)) != 0) {
497 ret = MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
498 goto exit;
499 }
500
501 if ((f = fopen(path, "wb")) == NULL) {
502 ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
503 goto exit;
504 }
505
506 if (fwrite(buf, 1, MBEDTLS_ENTROPY_BLOCK_SIZE, f) != MBEDTLS_ENTROPY_BLOCK_SIZE) {
507 ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
508 goto exit;
509 }
510
511 ret = 0;
512
513exit:
514 mbedtls_platform_zeroize(buf, sizeof(buf));
515
516 if (f != NULL) {
517 fclose(f);
518 }
519
520 return ret;
521}
522
523int mbedtls_entropy_update_seed_file(mbedtls_entropy_context *ctx, const char *path)
524{
525 int ret = 0;
526 FILE *f;
527 size_t n;
528 unsigned char buf[MBEDTLS_ENTROPY_MAX_SEED_SIZE];
529
530 if ((f = fopen(path, "rb")) == NULL) {
531 return MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
532 }
533
534 fseek(f, 0, SEEK_END);
535 n = (size_t) ftell(f);
536 fseek(f, 0, SEEK_SET);
537
538 if (n > MBEDTLS_ENTROPY_MAX_SEED_SIZE) {
539 n = MBEDTLS_ENTROPY_MAX_SEED_SIZE;
540 }
541
542 if (fread(buf, 1, n, f) != n) {
543 ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
544 } else {
545 ret = mbedtls_entropy_update_manual(ctx, buf, n);
546 }
547
548 fclose(f);
549
550 mbedtls_platform_zeroize(buf, sizeof(buf));
551
552 if (ret != 0) {
553 return ret;
554 }
555
556 return mbedtls_entropy_write_seed_file(ctx, path);
557}
558#endif /* MBEDTLS_FS_IO */
559
560#if defined(MBEDTLS_SELF_TEST)
561#if !defined(MBEDTLS_TEST_NULL_ENTROPY)
562/*
563 * Dummy source function
564 */
565static int entropy_dummy_source(void *data, unsigned char *output,
566 size_t len, size_t *olen)
567{
568 ((void) data);
569
570 memset(output, 0x2a, len);
571 *olen = len;
572
573 return 0;
574}
575#endif /* !MBEDTLS_TEST_NULL_ENTROPY */
576
577#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
578
579static int mbedtls_entropy_source_self_test_gather(unsigned char *buf, size_t buf_len)
580{
581 int ret = 0;
582 size_t entropy_len = 0;
583 size_t olen = 0;
584 size_t attempts = buf_len;
585
586 while (attempts > 0 && entropy_len < buf_len) {
587 if ((ret = mbedtls_hardware_poll(NULL, buf + entropy_len,
588 buf_len - entropy_len, &olen)) != 0) {
589 return ret;
590 }
591
592 entropy_len += olen;
593 attempts--;
594 }
595
596 if (entropy_len < buf_len) {
597 ret = 1;
598 }
599
600 return ret;
601}
602
603
604static int mbedtls_entropy_source_self_test_check_bits(const unsigned char *buf,
605 size_t buf_len)
606{
607 unsigned char set = 0xFF;
608 unsigned char unset = 0x00;
609 size_t i;
610
611 for (i = 0; i < buf_len; i++) {
612 set &= buf[i];
613 unset |= buf[i];
614 }
615
616 return set == 0xFF || unset == 0x00;
617}
618
619/*
620 * A test to ensure that the entropy sources are functioning correctly
621 * and there is no obvious failure. The test performs the following checks:
622 * - The entropy source is not providing only 0s (all bits unset) or 1s (all
623 * bits set).
624 * - The entropy source is not providing values in a pattern. Because the
625 * hardware could be providing data in an arbitrary length, this check polls
626 * the hardware entropy source twice and compares the result to ensure they
627 * are not equal.
628 * - The error code returned by the entropy source is not an error.
629 */
630int mbedtls_entropy_source_self_test(int verbose)
631{
632 int ret = 0;
633 unsigned char buf0[2 * sizeof(unsigned long long int)];
634 unsigned char buf1[2 * sizeof(unsigned long long int)];
635
636 if (verbose != 0) {
637 mbedtls_printf(" ENTROPY_BIAS test: ");
638 }
639
640 memset(buf0, 0x00, sizeof(buf0));
641 memset(buf1, 0x00, sizeof(buf1));
642
643 if ((ret = mbedtls_entropy_source_self_test_gather(buf0, sizeof(buf0))) != 0) {
644 goto cleanup;
645 }
646 if ((ret = mbedtls_entropy_source_self_test_gather(buf1, sizeof(buf1))) != 0) {
647 goto cleanup;
648 }
649
650 /* Make sure that the returned values are not all 0 or 1 */
651 if ((ret = mbedtls_entropy_source_self_test_check_bits(buf0, sizeof(buf0))) != 0) {
652 goto cleanup;
653 }
654 if ((ret = mbedtls_entropy_source_self_test_check_bits(buf1, sizeof(buf1))) != 0) {
655 goto cleanup;
656 }
657
658 /* Make sure that the entropy source is not returning values in a
659 * pattern */
660 ret = memcmp(buf0, buf1, sizeof(buf0)) == 0;
661
662cleanup:
663 if (verbose != 0) {
664 if (ret != 0) {
665 mbedtls_printf("failed\n");
666 } else {
667 mbedtls_printf("passed\n");
668 }
669
670 mbedtls_printf("\n");
671 }
672
673 return ret != 0;
674}
675
676#endif /* MBEDTLS_ENTROPY_HARDWARE_ALT */
677
678/*
679 * The actual entropy quality is hard to test, but we can at least
680 * test that the functions don't cause errors and write the correct
681 * amount of data to buffers.
682 */
683int mbedtls_entropy_self_test(int verbose)
684{
685 int ret = 1;
686#if !defined(MBEDTLS_TEST_NULL_ENTROPY)
687 mbedtls_entropy_context ctx;
688 unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
689 unsigned char acc[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
690 size_t i, j;
691#endif /* !MBEDTLS_TEST_NULL_ENTROPY */
692
693 if (verbose != 0) {
694 mbedtls_printf(" ENTROPY test: ");
695 }
696
697#if !defined(MBEDTLS_TEST_NULL_ENTROPY)
698 mbedtls_entropy_init(&ctx);
699
700 /* First do a gather to make sure we have default sources */
701 if ((ret = mbedtls_entropy_gather(&ctx)) != 0) {
702 goto cleanup;
703 }
704
705 ret = mbedtls_entropy_add_source(&ctx, entropy_dummy_source, NULL, 16,
706 MBEDTLS_ENTROPY_SOURCE_WEAK);
707 if (ret != 0) {
708 goto cleanup;
709 }
710
711 if ((ret = mbedtls_entropy_update_manual(&ctx, buf, sizeof(buf))) != 0) {
712 goto cleanup;
713 }
714
715 /*
716 * To test that mbedtls_entropy_func writes correct number of bytes:
717 * - use the whole buffer and rely on ASan to detect overruns
718 * - collect entropy 8 times and OR the result in an accumulator:
719 * any byte should then be 0 with probably 2^(-64), so requiring
720 * each of the 32 or 64 bytes to be non-zero has a false failure rate
721 * of at most 2^(-58) which is acceptable.
722 */
723 for (i = 0; i < 8; i++) {
724 if ((ret = mbedtls_entropy_func(&ctx, buf, sizeof(buf))) != 0) {
725 goto cleanup;
726 }
727
728 for (j = 0; j < sizeof(buf); j++) {
729 acc[j] |= buf[j];
730 }
731 }
732
733 for (j = 0; j < sizeof(buf); j++) {
734 if (acc[j] == 0) {
735 ret = 1;
736 goto cleanup;
737 }
738 }
739
740#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
741 if ((ret = mbedtls_entropy_source_self_test(0)) != 0) {
742 goto cleanup;
743 }
744#endif
745
746cleanup:
747 mbedtls_entropy_free(&ctx);
748#endif /* !MBEDTLS_TEST_NULL_ENTROPY */
749
750 if (verbose != 0) {
751 if (ret != 0) {
752 mbedtls_printf("failed\n");
753 } else {
754 mbedtls_printf("passed\n");
755 }
756
757 mbedtls_printf("\n");
758 }
759
760 return ret != 0;
761}
762#endif /* MBEDTLS_SELF_TEST */
763
764#endif /* MBEDTLS_ENTROPY_C */
765