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 && 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);
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 if (prediction_resistance) {
188 * We don't have any entropy sources that comply with the NIST
189 * standard to provide prediction resistance (see NIST SP 800-90C,
192 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY,
193 RAND_R_PREDICTION_RESISTANCE_NOT_SUPPORTED);
197 /* Get entropy by polling system entropy sources. */
198 entropy_available = rand_pool_acquire_entropy(pool);
201 if (entropy_available > 0) {
202 ret = rand_pool_length(pool);
203 *pout = rand_pool_detach(pool);
207 if (drbg->seed_pool == NULL)
208 rand_pool_free(pool);
213 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
216 void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
217 unsigned char *out, size_t outlen)
219 if (drbg->seed_pool == NULL)
220 OPENSSL_secure_clear_free(out, outlen);
225 * Implements the get_nonce() callback (see RAND_DRBG_set_callbacks())
228 size_t rand_drbg_get_nonce(RAND_DRBG *drbg,
229 unsigned char **pout,
230 int entropy, size_t min_len, size_t max_len)
240 pool = rand_pool_new(0, min_len, max_len);
244 if (rand_pool_add_nonce_data(pool) == 0)
247 data.instance = drbg;
248 CRYPTO_atomic_add(&rand_nonce_count, 1, &data.count, rand_nonce_lock);
250 if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)
253 ret = rand_pool_length(pool);
254 *pout = rand_pool_detach(pool);
257 rand_pool_free(pool);
263 * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())
266 void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,
267 unsigned char *out, size_t outlen)
269 OPENSSL_secure_clear_free(out, outlen);
273 * Generate additional data that can be used for the drbg. The data does
274 * not need to contain entropy, but it's useful if it contains at least
275 * some bits that are unpredictable.
277 * Returns 0 on failure.
279 * On success it allocates a buffer at |*pout| and returns the length of
280 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
282 size_t rand_drbg_get_additional_data(RAND_POOL *pool, unsigned char **pout)
286 if (rand_pool_add_additional_data(pool) == 0)
289 ret = rand_pool_length(pool);
290 *pout = rand_pool_detach(pool);
296 void rand_drbg_cleanup_additional_data(RAND_POOL *pool, unsigned char *out)
298 rand_pool_reattach(pool, out);
306 DEFINE_RUN_ONCE_STATIC(do_rand_init)
308 #ifndef OPENSSL_NO_ENGINE
309 rand_engine_lock = CRYPTO_THREAD_lock_new();
310 if (rand_engine_lock == NULL)
314 rand_meth_lock = CRYPTO_THREAD_lock_new();
315 if (rand_meth_lock == NULL)
318 rand_nonce_lock = CRYPTO_THREAD_lock_new();
319 if (rand_nonce_lock == NULL)
322 if (!rand_pool_init())
329 CRYPTO_THREAD_lock_free(rand_nonce_lock);
330 rand_nonce_lock = NULL;
332 CRYPTO_THREAD_lock_free(rand_meth_lock);
333 rand_meth_lock = NULL;
335 #ifndef OPENSSL_NO_ENGINE
336 CRYPTO_THREAD_lock_free(rand_engine_lock);
337 rand_engine_lock = NULL;
342 void rand_cleanup_int(void)
344 const RAND_METHOD *meth = default_RAND_meth;
349 if (meth != NULL && meth->cleanup != NULL)
351 RAND_set_rand_method(NULL);
353 #ifndef OPENSSL_NO_ENGINE
354 CRYPTO_THREAD_lock_free(rand_engine_lock);
355 rand_engine_lock = NULL;
357 CRYPTO_THREAD_lock_free(rand_meth_lock);
358 rand_meth_lock = NULL;
359 CRYPTO_THREAD_lock_free(rand_nonce_lock);
360 rand_nonce_lock = NULL;
365 * RAND_close_seed_files() ensures that any seed file decriptors are
368 void RAND_keep_random_devices_open(int keep)
370 if (RUN_ONCE(&rand_init, do_rand_init))
371 rand_pool_keep_random_devices_open(keep);
375 * RAND_poll() reseeds the default RNG using random input
377 * The random input is obtained from polling various entropy
378 * sources which depend on the operating system and are
379 * configurable via the --with-rand-seed configure option.
385 RAND_POOL *pool = NULL;
387 const RAND_METHOD *meth = RAND_get_rand_method();
389 if (meth == RAND_OpenSSL()) {
390 /* fill random pool and seed the master DRBG */
391 RAND_DRBG *drbg = RAND_DRBG_get0_master();
396 rand_drbg_lock(drbg);
397 ret = rand_drbg_restart(drbg, NULL, 0, 0);
398 rand_drbg_unlock(drbg);
403 /* fill random pool and seed the current legacy RNG */
404 pool = rand_pool_new(RAND_DRBG_STRENGTH,
405 RAND_DRBG_STRENGTH / 8,
406 RAND_POOL_MAX_LENGTH);
410 if (rand_pool_acquire_entropy(pool) == 0)
413 if (meth->add == NULL
414 || meth->add(rand_pool_buffer(pool),
415 rand_pool_length(pool),
416 (rand_pool_entropy(pool) / 8.0)) == 0)
423 rand_pool_free(pool);
428 * Allocate memory and initialize a new random pool
431 RAND_POOL *rand_pool_new(int entropy_requested, size_t min_len, size_t max_len)
433 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
436 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
440 pool->min_len = min_len;
441 pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ?
442 RAND_POOL_MAX_LENGTH : max_len;
444 pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
445 if (pool->buffer == NULL) {
446 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
450 pool->entropy_requested = entropy_requested;
460 * Attach new random pool to the given buffer
462 * This function is intended to be used only for feeding random data
463 * provided by RAND_add() and RAND_seed() into the <master> DRBG.
465 RAND_POOL *rand_pool_attach(const unsigned char *buffer, size_t len,
468 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
471 RANDerr(RAND_F_RAND_POOL_ATTACH, ERR_R_MALLOC_FAILURE);
476 * The const needs to be cast away, but attached buffers will not be
477 * modified (in contrary to allocated buffers which are zeroed and
480 pool->buffer = (unsigned char *) buffer;
485 pool->min_len = pool->max_len = pool->len;
486 pool->entropy = entropy;
492 * Free |pool|, securely erasing its buffer.
494 void rand_pool_free(RAND_POOL *pool)
500 * Although it would be advisable from a cryptographical viewpoint,
501 * we are not allowed to clear attached buffers, since they are passed
502 * to rand_pool_attach() as `const unsigned char*`.
503 * (see corresponding comment in rand_pool_attach()).
506 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
511 * Return the |pool|'s buffer to the caller (readonly).
513 const unsigned char *rand_pool_buffer(RAND_POOL *pool)
519 * Return the |pool|'s entropy to the caller.
521 size_t rand_pool_entropy(RAND_POOL *pool)
523 return pool->entropy;
527 * Return the |pool|'s buffer length to the caller.
529 size_t rand_pool_length(RAND_POOL *pool)
535 * Detach the |pool| buffer and return it to the caller.
536 * It's the responsibility of the caller to free the buffer
537 * using OPENSSL_secure_clear_free() or to re-attach it
538 * again to the pool using rand_pool_reattach().
540 unsigned char *rand_pool_detach(RAND_POOL *pool)
542 unsigned char *ret = pool->buffer;
549 * Re-attach the |pool| buffer. It is only allowed to pass
550 * the |buffer| which was previously detached from the same pool.
552 void rand_pool_reattach(RAND_POOL *pool, unsigned char *buffer)
554 pool->buffer = buffer;
555 OPENSSL_cleanse(pool->buffer, pool->len);
560 * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one
561 * need to obtain at least |bits| bits of entropy?
563 #define ENTROPY_TO_BYTES(bits, entropy_factor) \
564 (((bits) * (entropy_factor) + 7) / 8)
568 * Checks whether the |pool|'s entropy is available to the caller.
569 * This is the case when entropy count and buffer length are high enough.
572 * |entropy| if the entropy count and buffer size is large enough
575 size_t rand_pool_entropy_available(RAND_POOL *pool)
577 if (pool->entropy < pool->entropy_requested)
580 if (pool->len < pool->min_len)
583 return pool->entropy;
587 * Returns the (remaining) amount of entropy needed to fill
591 size_t rand_pool_entropy_needed(RAND_POOL *pool)
593 if (pool->entropy < pool->entropy_requested)
594 return pool->entropy_requested - pool->entropy;
600 * Returns the number of bytes needed to fill the pool, assuming
601 * the input has 1 / |entropy_factor| entropy bits per data bit.
602 * In case of an error, 0 is returned.
605 size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)
608 size_t entropy_needed = rand_pool_entropy_needed(pool);
610 if (entropy_factor < 1) {
611 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
615 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor);
617 if (bytes_needed > pool->max_len - pool->len) {
618 /* not enough space left */
619 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
623 if (pool->len < pool->min_len &&
624 bytes_needed < pool->min_len - pool->len)
625 /* to meet the min_len requirement */
626 bytes_needed = pool->min_len - pool->len;
631 /* Returns the remaining number of bytes available */
632 size_t rand_pool_bytes_remaining(RAND_POOL *pool)
634 return pool->max_len - pool->len;
638 * Add random bytes to the random pool.
640 * It is expected that the |buffer| contains |len| bytes of
641 * random input which contains at least |entropy| bits of
644 * Returns 1 if the added amount is adequate, otherwise 0
646 int rand_pool_add(RAND_POOL *pool,
647 const unsigned char *buffer, size_t len, size_t entropy)
649 if (len > pool->max_len - pool->len) {
650 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
654 if (pool->buffer == NULL) {
655 RANDerr(RAND_F_RAND_POOL_ADD, ERR_R_INTERNAL_ERROR);
660 memcpy(pool->buffer + pool->len, buffer, len);
662 pool->entropy += entropy;
669 * Start to add random bytes to the random pool in-place.
671 * Reserves the next |len| bytes for adding random bytes in-place
672 * and returns a pointer to the buffer.
673 * The caller is allowed to copy up to |len| bytes into the buffer.
674 * If |len| == 0 this is considered a no-op and a NULL pointer
675 * is returned without producing an error message.
677 * After updating the buffer, rand_pool_add_end() needs to be called
678 * to finish the udpate operation (see next comment).
680 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
685 if (len > pool->max_len - pool->len) {
686 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
690 if (pool->buffer == NULL) {
691 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, ERR_R_INTERNAL_ERROR);
695 return pool->buffer + pool->len;
699 * Finish to add random bytes to the random pool in-place.
701 * Finishes an in-place update of the random pool started by
702 * rand_pool_add_begin() (see previous comment).
703 * It is expected that |len| bytes of random input have been added
704 * to the buffer which contain at least |entropy| bits of randomness.
705 * It is allowed to add less bytes than originally reserved.
707 int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
709 if (len > pool->max_len - pool->len) {
710 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
716 pool->entropy += entropy;
722 int RAND_set_rand_method(const RAND_METHOD *meth)
724 if (!RUN_ONCE(&rand_init, do_rand_init))
727 CRYPTO_THREAD_write_lock(rand_meth_lock);
728 #ifndef OPENSSL_NO_ENGINE
729 ENGINE_finish(funct_ref);
732 default_RAND_meth = meth;
733 CRYPTO_THREAD_unlock(rand_meth_lock);
737 const RAND_METHOD *RAND_get_rand_method(void)
739 const RAND_METHOD *tmp_meth = NULL;
741 if (!RUN_ONCE(&rand_init, do_rand_init))
744 CRYPTO_THREAD_write_lock(rand_meth_lock);
745 if (default_RAND_meth == NULL) {
746 #ifndef OPENSSL_NO_ENGINE
749 /* If we have an engine that can do RAND, use it. */
750 if ((e = ENGINE_get_default_RAND()) != NULL
751 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
753 default_RAND_meth = tmp_meth;
756 default_RAND_meth = &rand_meth;
759 default_RAND_meth = &rand_meth;
762 tmp_meth = default_RAND_meth;
763 CRYPTO_THREAD_unlock(rand_meth_lock);
767 #ifndef OPENSSL_NO_ENGINE
768 int RAND_set_rand_engine(ENGINE *engine)
770 const RAND_METHOD *tmp_meth = NULL;
772 if (!RUN_ONCE(&rand_init, do_rand_init))
775 if (engine != NULL) {
776 if (!ENGINE_init(engine))
778 tmp_meth = ENGINE_get_RAND(engine);
779 if (tmp_meth == NULL) {
780 ENGINE_finish(engine);
784 CRYPTO_THREAD_write_lock(rand_engine_lock);
785 /* This function releases any prior ENGINE so call it first */
786 RAND_set_rand_method(tmp_meth);
788 CRYPTO_THREAD_unlock(rand_engine_lock);
793 void RAND_seed(const void *buf, int num)
795 const RAND_METHOD *meth = RAND_get_rand_method();
797 if (meth->seed != NULL)
798 meth->seed(buf, num);
801 void RAND_add(const void *buf, int num, double randomness)
803 const RAND_METHOD *meth = RAND_get_rand_method();
805 if (meth->add != NULL)
806 meth->add(buf, num, randomness);
810 * This function is not part of RAND_METHOD, so if we're not using
811 * the default method, then just call RAND_bytes(). Otherwise make
812 * sure we're instantiated and use the private DRBG.
814 int RAND_priv_bytes(unsigned char *buf, int num)
816 const RAND_METHOD *meth = RAND_get_rand_method();
820 if (meth != RAND_OpenSSL())
821 return RAND_bytes(buf, num);
823 drbg = RAND_DRBG_get0_private();
827 ret = RAND_DRBG_bytes(drbg, buf, num);
831 int RAND_bytes(unsigned char *buf, int num)
833 const RAND_METHOD *meth = RAND_get_rand_method();
835 if (meth->bytes != NULL)
836 return meth->bytes(buf, num);
837 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
841 #if !OPENSSL_API_1_1_0
842 int RAND_pseudo_bytes(unsigned char *buf, int num)
844 const RAND_METHOD *meth = RAND_get_rand_method();
846 if (meth->pseudorand != NULL)
847 return meth->pseudorand(buf, num);
852 int RAND_status(void)
854 const RAND_METHOD *meth = RAND_get_rand_method();
856 if (meth->status != NULL)
857 return meth->status();