2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
12 #include "internal/cryptlib.h"
13 #include <openssl/opensslconf.h>
14 #include "internal/rand_int.h"
15 #include <openssl/engine.h>
16 #include "internal/thread_once.h"
20 #ifndef OPENSSL_NO_ENGINE
21 /* non-NULL if default_RAND_meth is ENGINE-provided */
22 static ENGINE *funct_ref;
23 static CRYPTO_RWLOCK *rand_engine_lock;
25 static CRYPTO_RWLOCK *rand_meth_lock;
26 static const RAND_METHOD *default_RAND_meth;
27 static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT;
31 static CRYPTO_RWLOCK *rand_nonce_lock;
32 static int rand_nonce_count;
34 static int rand_inited = 0;
36 #ifdef OPENSSL_RAND_SEED_RDTSC
38 * IMPORTANT NOTE: It is not currently possible to use this code
39 * because we are not sure about the amount of randomness it provides.
40 * Some SP900 tests have been run, but there is internal skepticism.
41 * So for now this code is not used.
43 # error "RDTSC enabled? Should not be possible!"
46 * Acquire entropy from high-speed clock
48 * Since we get some randomness from the low-order bits of the
49 * high-speed clock, it can help.
51 * Returns the total entropy count, if it exceeds the requested
52 * entropy count. Otherwise, returns an entropy count of 0.
54 size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool)
59 if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) {
60 for (i = 0; i < TSC_READ_COUNT; i++) {
61 c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
62 rand_pool_add(pool, &c, 1, 4);
65 return rand_pool_entropy_available(pool);
69 #ifdef OPENSSL_RAND_SEED_RDCPU
70 size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf, size_t len);
71 size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf, size_t len);
73 extern unsigned int OPENSSL_ia32cap_P[];
76 * Acquire entropy using Intel-specific cpu instructions
78 * Uses the RDSEED instruction if available, otherwise uses
79 * RDRAND if available.
81 * For the differences between RDSEED and RDRAND, and why RDSEED
82 * is the preferred choice, see https://goo.gl/oK3KcN
84 * Returns the total entropy count, if it exceeds the requested
85 * entropy count. Otherwise, returns an entropy count of 0.
87 size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool)
90 unsigned char *buffer;
92 bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
93 if (bytes_needed > 0) {
94 buffer = rand_pool_add_begin(pool, bytes_needed);
97 /* Whichever comes first, use RDSEED, RDRAND or nothing */
98 if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) {
99 if (OPENSSL_ia32_rdseed_bytes(buffer, bytes_needed)
101 rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
103 } else if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
104 if (OPENSSL_ia32_rdrand_bytes(buffer, bytes_needed)
106 rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
109 rand_pool_add_end(pool, 0, 0);
114 return rand_pool_entropy_available(pool);
120 * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())
122 * If the DRBG has a parent, then the required amount of entropy input
123 * is fetched using the parent's RAND_DRBG_generate().
125 * Otherwise, the entropy is polled from the system entropy sources
126 * using rand_pool_acquire_entropy().
128 * If a random pool has been added to the DRBG using RAND_add(), then
129 * its entropy will be used up first.
131 size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
132 unsigned char **pout,
133 int entropy, size_t min_len, size_t max_len,
134 int prediction_resistance)
137 size_t entropy_available = 0;
140 if (drbg->parent != NULL && drbg->strength > drbg->parent->strength) {
142 * We currently don't support the algorithm from NIST SP 800-90C
143 * 10.1.2 to use a weaker DRBG as source
145 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY, RAND_R_PARENT_STRENGTH_TOO_WEAK);
149 if (drbg->seed_pool != NULL) {
150 pool = drbg->seed_pool;
151 pool->entropy_requested = entropy;
153 pool = rand_pool_new(entropy, min_len, max_len);
158 if (drbg->parent != NULL) {
159 size_t bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
160 unsigned char *buffer = rand_pool_add_begin(pool, bytes_needed);
162 if (buffer != NULL) {
166 * Get random from parent, include our state as additional input.
167 * Our lock is already held, but we need to lock our parent before
168 * generating bits from it. (Note: taking the lock will be a no-op
169 * if locking if drbg->parent->lock == NULL.)
171 rand_drbg_lock(drbg->parent);
172 if (RAND_DRBG_generate(drbg->parent,
173 buffer, bytes_needed,
174 prediction_resistance,
176 bytes = bytes_needed;
177 drbg->reseed_next_counter
178 = tsan_load(&drbg->parent->reseed_prop_counter);
179 rand_drbg_unlock(drbg->parent);
181 rand_pool_add_end(pool, bytes, 8 * bytes);
182 entropy_available = rand_pool_entropy_available(pool);
186 /* Get entropy by polling system entropy sources. */
187 entropy_available = rand_pool_acquire_entropy(pool);
190 if (entropy_available > 0) {
191 ret = rand_pool_length(pool);
192 *pout = rand_pool_detach(pool);
195 if (drbg->seed_pool == NULL)
196 rand_pool_free(pool);
201 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
204 void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
205 unsigned char *out, size_t outlen)
207 if (drbg->seed_pool == NULL)
208 OPENSSL_secure_clear_free(out, outlen);
213 * Implements the get_nonce() callback (see RAND_DRBG_set_callbacks())
216 size_t rand_drbg_get_nonce(RAND_DRBG *drbg,
217 unsigned char **pout,
218 int entropy, size_t min_len, size_t max_len)
228 memset(&data, 0, sizeof(data));
229 pool = rand_pool_new(0, min_len, max_len);
233 if (rand_pool_add_nonce_data(pool) == 0)
236 data.instance = drbg;
237 CRYPTO_atomic_add(&rand_nonce_count, 1, &data.count, rand_nonce_lock);
239 if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)
242 ret = rand_pool_length(pool);
243 *pout = rand_pool_detach(pool);
246 rand_pool_free(pool);
252 * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())
255 void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,
256 unsigned char *out, size_t outlen)
258 OPENSSL_secure_clear_free(out, outlen);
262 * Generate additional data that can be used for the drbg. The data does
263 * not need to contain entropy, but it's useful if it contains at least
264 * some bits that are unpredictable.
266 * Returns 0 on failure.
268 * On success it allocates a buffer at |*pout| and returns the length of
269 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
271 size_t rand_drbg_get_additional_data(RAND_POOL *pool, unsigned char **pout)
275 if (rand_pool_add_additional_data(pool) == 0)
278 ret = rand_pool_length(pool);
279 *pout = rand_pool_detach(pool);
285 void rand_drbg_cleanup_additional_data(RAND_POOL *pool, unsigned char *out)
287 rand_pool_reattach(pool, out);
295 DEFINE_RUN_ONCE_STATIC(do_rand_init)
297 #ifndef OPENSSL_NO_ENGINE
298 rand_engine_lock = CRYPTO_THREAD_lock_new();
299 if (rand_engine_lock == NULL)
303 rand_meth_lock = CRYPTO_THREAD_lock_new();
304 if (rand_meth_lock == NULL)
307 rand_nonce_lock = CRYPTO_THREAD_lock_new();
308 if (rand_nonce_lock == NULL)
311 if (!rand_pool_init())
318 CRYPTO_THREAD_lock_free(rand_nonce_lock);
319 rand_nonce_lock = NULL;
321 CRYPTO_THREAD_lock_free(rand_meth_lock);
322 rand_meth_lock = NULL;
324 #ifndef OPENSSL_NO_ENGINE
325 CRYPTO_THREAD_lock_free(rand_engine_lock);
326 rand_engine_lock = NULL;
331 void rand_cleanup_int(void)
333 const RAND_METHOD *meth = default_RAND_meth;
338 if (meth != NULL && meth->cleanup != NULL)
340 RAND_set_rand_method(NULL);
342 #ifndef OPENSSL_NO_ENGINE
343 CRYPTO_THREAD_lock_free(rand_engine_lock);
344 rand_engine_lock = NULL;
346 CRYPTO_THREAD_lock_free(rand_meth_lock);
347 rand_meth_lock = NULL;
348 CRYPTO_THREAD_lock_free(rand_nonce_lock);
349 rand_nonce_lock = NULL;
354 * RAND_close_seed_files() ensures that any seed file decriptors are
357 void RAND_keep_random_devices_open(int keep)
359 if (RUN_ONCE(&rand_init, do_rand_init))
360 rand_pool_keep_random_devices_open(keep);
364 * RAND_poll() reseeds the default RNG using random input
366 * The random input is obtained from polling various entropy
367 * sources which depend on the operating system and are
368 * configurable via the --with-rand-seed configure option.
374 RAND_POOL *pool = NULL;
376 const RAND_METHOD *meth = RAND_get_rand_method();
378 if (meth == RAND_OpenSSL()) {
379 /* fill random pool and seed the master DRBG */
380 RAND_DRBG *drbg = RAND_DRBG_get0_master();
385 rand_drbg_lock(drbg);
386 ret = rand_drbg_restart(drbg, NULL, 0, 0);
387 rand_drbg_unlock(drbg);
392 /* fill random pool and seed the current legacy RNG */
393 pool = rand_pool_new(RAND_DRBG_STRENGTH,
394 (RAND_DRBG_STRENGTH + 7) / 8,
395 RAND_POOL_MAX_LENGTH);
399 if (rand_pool_acquire_entropy(pool) == 0)
402 if (meth->add == NULL
403 || meth->add(rand_pool_buffer(pool),
404 rand_pool_length(pool),
405 (rand_pool_entropy(pool) / 8.0)) == 0)
412 rand_pool_free(pool);
417 * Allocate memory and initialize a new random pool
420 RAND_POOL *rand_pool_new(int entropy_requested, size_t min_len, size_t max_len)
422 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
425 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
429 pool->min_len = min_len;
430 pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ?
431 RAND_POOL_MAX_LENGTH : max_len;
433 pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
434 if (pool->buffer == NULL) {
435 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
439 pool->entropy_requested = entropy_requested;
449 * Attach new random pool to the given buffer
451 * This function is intended to be used only for feeding random data
452 * provided by RAND_add() and RAND_seed() into the <master> DRBG.
454 RAND_POOL *rand_pool_attach(const unsigned char *buffer, size_t len,
457 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
460 RANDerr(RAND_F_RAND_POOL_ATTACH, ERR_R_MALLOC_FAILURE);
465 * The const needs to be cast away, but attached buffers will not be
466 * modified (in contrary to allocated buffers which are zeroed and
469 pool->buffer = (unsigned char *) buffer;
474 pool->min_len = pool->max_len = pool->len;
475 pool->entropy = entropy;
481 * Free |pool|, securely erasing its buffer.
483 void rand_pool_free(RAND_POOL *pool)
489 * Although it would be advisable from a cryptographical viewpoint,
490 * we are not allowed to clear attached buffers, since they are passed
491 * to rand_pool_attach() as `const unsigned char*`.
492 * (see corresponding comment in rand_pool_attach()).
495 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
500 * Return the |pool|'s buffer to the caller (readonly).
502 const unsigned char *rand_pool_buffer(RAND_POOL *pool)
508 * Return the |pool|'s entropy to the caller.
510 size_t rand_pool_entropy(RAND_POOL *pool)
512 return pool->entropy;
516 * Return the |pool|'s buffer length to the caller.
518 size_t rand_pool_length(RAND_POOL *pool)
524 * Detach the |pool| buffer and return it to the caller.
525 * It's the responsibility of the caller to free the buffer
526 * using OPENSSL_secure_clear_free() or to re-attach it
527 * again to the pool using rand_pool_reattach().
529 unsigned char *rand_pool_detach(RAND_POOL *pool)
531 unsigned char *ret = pool->buffer;
538 * Re-attach the |pool| buffer. It is only allowed to pass
539 * the |buffer| which was previously detached from the same pool.
541 void rand_pool_reattach(RAND_POOL *pool, unsigned char *buffer)
543 pool->buffer = buffer;
544 OPENSSL_cleanse(pool->buffer, pool->len);
549 * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one
550 * need to obtain at least |bits| bits of entropy?
552 #define ENTROPY_TO_BYTES(bits, entropy_factor) \
553 (((bits) * (entropy_factor) + 7) / 8)
557 * Checks whether the |pool|'s entropy is available to the caller.
558 * This is the case when entropy count and buffer length are high enough.
561 * |entropy| if the entropy count and buffer size is large enough
564 size_t rand_pool_entropy_available(RAND_POOL *pool)
566 if (pool->entropy < pool->entropy_requested)
569 if (pool->len < pool->min_len)
572 return pool->entropy;
576 * Returns the (remaining) amount of entropy needed to fill
580 size_t rand_pool_entropy_needed(RAND_POOL *pool)
582 if (pool->entropy < pool->entropy_requested)
583 return pool->entropy_requested - pool->entropy;
589 * Returns the number of bytes needed to fill the pool, assuming
590 * the input has 1 / |entropy_factor| entropy bits per data bit.
591 * In case of an error, 0 is returned.
594 size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)
597 size_t entropy_needed = rand_pool_entropy_needed(pool);
599 if (entropy_factor < 1) {
600 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
604 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor);
606 if (bytes_needed > pool->max_len - pool->len) {
607 /* not enough space left */
608 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
612 if (pool->len < pool->min_len &&
613 bytes_needed < pool->min_len - pool->len)
614 /* to meet the min_len requirement */
615 bytes_needed = pool->min_len - pool->len;
620 /* Returns the remaining number of bytes available */
621 size_t rand_pool_bytes_remaining(RAND_POOL *pool)
623 return pool->max_len - pool->len;
627 * Add random bytes to the random pool.
629 * It is expected that the |buffer| contains |len| bytes of
630 * random input which contains at least |entropy| bits of
633 * Returns 1 if the added amount is adequate, otherwise 0
635 int rand_pool_add(RAND_POOL *pool,
636 const unsigned char *buffer, size_t len, size_t entropy)
638 if (len > pool->max_len - pool->len) {
639 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
643 if (pool->buffer == NULL) {
644 RANDerr(RAND_F_RAND_POOL_ADD, ERR_R_INTERNAL_ERROR);
649 memcpy(pool->buffer + pool->len, buffer, len);
651 pool->entropy += entropy;
658 * Start to add random bytes to the random pool in-place.
660 * Reserves the next |len| bytes for adding random bytes in-place
661 * and returns a pointer to the buffer.
662 * The caller is allowed to copy up to |len| bytes into the buffer.
663 * If |len| == 0 this is considered a no-op and a NULL pointer
664 * is returned without producing an error message.
666 * After updating the buffer, rand_pool_add_end() needs to be called
667 * to finish the udpate operation (see next comment).
669 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
674 if (len > pool->max_len - pool->len) {
675 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
679 if (pool->buffer == NULL) {
680 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, ERR_R_INTERNAL_ERROR);
684 return pool->buffer + pool->len;
688 * Finish to add random bytes to the random pool in-place.
690 * Finishes an in-place update of the random pool started by
691 * rand_pool_add_begin() (see previous comment).
692 * It is expected that |len| bytes of random input have been added
693 * to the buffer which contain at least |entropy| bits of randomness.
694 * It is allowed to add less bytes than originally reserved.
696 int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
698 if (len > pool->max_len - pool->len) {
699 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
705 pool->entropy += entropy;
711 int RAND_set_rand_method(const RAND_METHOD *meth)
713 if (!RUN_ONCE(&rand_init, do_rand_init))
716 CRYPTO_THREAD_write_lock(rand_meth_lock);
717 #ifndef OPENSSL_NO_ENGINE
718 ENGINE_finish(funct_ref);
721 default_RAND_meth = meth;
722 CRYPTO_THREAD_unlock(rand_meth_lock);
726 const RAND_METHOD *RAND_get_rand_method(void)
728 const RAND_METHOD *tmp_meth = NULL;
730 if (!RUN_ONCE(&rand_init, do_rand_init))
733 CRYPTO_THREAD_write_lock(rand_meth_lock);
734 if (default_RAND_meth == NULL) {
735 #ifndef OPENSSL_NO_ENGINE
738 /* If we have an engine that can do RAND, use it. */
739 if ((e = ENGINE_get_default_RAND()) != NULL
740 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
742 default_RAND_meth = tmp_meth;
745 default_RAND_meth = &rand_meth;
748 default_RAND_meth = &rand_meth;
751 tmp_meth = default_RAND_meth;
752 CRYPTO_THREAD_unlock(rand_meth_lock);
756 #ifndef OPENSSL_NO_ENGINE
757 int RAND_set_rand_engine(ENGINE *engine)
759 const RAND_METHOD *tmp_meth = NULL;
761 if (!RUN_ONCE(&rand_init, do_rand_init))
764 if (engine != NULL) {
765 if (!ENGINE_init(engine))
767 tmp_meth = ENGINE_get_RAND(engine);
768 if (tmp_meth == NULL) {
769 ENGINE_finish(engine);
773 CRYPTO_THREAD_write_lock(rand_engine_lock);
774 /* This function releases any prior ENGINE so call it first */
775 RAND_set_rand_method(tmp_meth);
777 CRYPTO_THREAD_unlock(rand_engine_lock);
782 void RAND_seed(const void *buf, int num)
784 const RAND_METHOD *meth = RAND_get_rand_method();
786 if (meth->seed != NULL)
787 meth->seed(buf, num);
790 void RAND_add(const void *buf, int num, double randomness)
792 const RAND_METHOD *meth = RAND_get_rand_method();
794 if (meth->add != NULL)
795 meth->add(buf, num, randomness);
799 * This function is not part of RAND_METHOD, so if we're not using
800 * the default method, then just call RAND_bytes(). Otherwise make
801 * sure we're instantiated and use the private DRBG.
803 int RAND_priv_bytes(unsigned char *buf, int num)
805 const RAND_METHOD *meth = RAND_get_rand_method();
809 if (meth != RAND_OpenSSL())
810 return RAND_bytes(buf, num);
812 drbg = RAND_DRBG_get0_private();
816 ret = RAND_DRBG_bytes(drbg, buf, num);
820 int RAND_bytes(unsigned char *buf, int num)
822 const RAND_METHOD *meth = RAND_get_rand_method();
824 if (meth->bytes != NULL)
825 return meth->bytes(buf, num);
826 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
830 #if !OPENSSL_API_1_1_0
831 int RAND_pseudo_bytes(unsigned char *buf, int num)
833 const RAND_METHOD *meth = RAND_get_rand_method();
835 if (meth->pseudorand != NULL)
836 return meth->pseudorand(buf, num);
841 int RAND_status(void)
843 const RAND_METHOD *meth = RAND_get_rand_method();
845 if (meth->status != NULL)
846 return meth->status();