2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (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();