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_cleaning_up
= 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
->pool
!= NULL
) {
151 pool
->entropy_requested
= entropy
;
153 pool
= rand_pool_new(entropy
, min_len
, max_len
);
157 size_t bytes_needed
= rand_pool_bytes_needed(pool
, 1 /*entropy_factor*/);
158 unsigned char *buffer
= rand_pool_add_begin(pool
, bytes_needed
);
160 if (buffer
!= NULL
) {
164 * Get random from parent, include our state as additional input.
165 * Our lock is already held, but we need to lock our parent before
166 * generating bits from it. (Note: taking the lock will be a no-op
167 * if locking if drbg->parent->lock == NULL.)
169 rand_drbg_lock(drbg
->parent
);
170 if (RAND_DRBG_generate(drbg
->parent
,
171 buffer
, bytes_needed
,
172 prediction_resistance
,
174 bytes
= bytes_needed
;
175 rand_drbg_unlock(drbg
->parent
);
177 rand_pool_add_end(pool
, bytes
, 8 * bytes
);
178 entropy_available
= rand_pool_entropy_available(pool
);
182 if (prediction_resistance
) {
184 * We don't have any entropy sources that comply with the NIST
185 * standard to provide prediction resistance (see NIST SP 800-90C,
188 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY
,
189 RAND_R_PREDICTION_RESISTANCE_NOT_SUPPORTED
);
193 /* Get entropy by polling system entropy sources. */
194 entropy_available
= rand_pool_acquire_entropy(pool
);
197 if (entropy_available
> 0) {
198 ret
= rand_pool_length(pool
);
199 *pout
= rand_pool_detach(pool
);
203 /* we need to reset drbg->pool in the error case */
204 if (ret
== 0 && drbg
->pool
!= NULL
)
207 rand_pool_free(pool
);
212 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
215 void rand_drbg_cleanup_entropy(RAND_DRBG
*drbg
,
216 unsigned char *out
, size_t outlen
)
218 if (drbg
->pool
== NULL
)
219 OPENSSL_secure_clear_free(out
, outlen
);
226 * Implements the get_nonce() callback (see RAND_DRBG_set_callbacks())
229 size_t rand_drbg_get_nonce(RAND_DRBG
*drbg
,
230 unsigned char **pout
,
231 int entropy
, size_t min_len
, size_t max_len
)
241 pool
= rand_pool_new(0, min_len
, max_len
);
245 if (rand_pool_add_nonce_data(pool
) == 0)
248 data
.instance
= drbg
;
249 CRYPTO_atomic_add(&rand_nonce_count
, 1, &data
.count
, rand_nonce_lock
);
251 if (rand_pool_add(pool
, (unsigned char *)&data
, sizeof(data
), 0) == 0)
254 ret
= rand_pool_length(pool
);
255 *pout
= rand_pool_detach(pool
);
258 rand_pool_free(pool
);
264 * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())
267 void rand_drbg_cleanup_nonce(RAND_DRBG
*drbg
,
268 unsigned char *out
, size_t outlen
)
270 OPENSSL_secure_clear_free(out
, outlen
);
274 * Generate additional data that can be used for the drbg. The data does
275 * not need to contain entropy, but it's useful if it contains at least
276 * some bits that are unpredictable.
278 * Returns 0 on failure.
280 * On success it allocates a buffer at |*pout| and returns the length of
281 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
283 size_t rand_drbg_get_additional_data(unsigned char **pout
, size_t max_len
)
288 pool
= rand_pool_new(0, 0, max_len
);
292 if (rand_pool_add_additional_data(pool
) == 0)
295 ret
= rand_pool_length(pool
);
296 *pout
= rand_pool_detach(pool
);
299 rand_pool_free(pool
);
304 void rand_drbg_cleanup_additional_data(unsigned char *out
, size_t outlen
)
306 OPENSSL_secure_clear_free(out
, outlen
);
314 DEFINE_RUN_ONCE_STATIC(do_rand_init
)
316 #ifndef OPENSSL_NO_ENGINE
317 rand_engine_lock
= CRYPTO_THREAD_lock_new();
318 if (rand_engine_lock
== NULL
)
322 rand_meth_lock
= CRYPTO_THREAD_lock_new();
323 if (rand_meth_lock
== NULL
)
326 rand_nonce_lock
= CRYPTO_THREAD_lock_new();
327 if (rand_nonce_lock
== NULL
)
330 if (!rand_cleaning_up
&& !rand_pool_init())
338 CRYPTO_THREAD_lock_free(rand_meth_lock
);
339 rand_meth_lock
= NULL
;
341 #ifndef OPENSSL_NO_ENGINE
342 CRYPTO_THREAD_lock_free(rand_engine_lock
);
343 rand_engine_lock
= NULL
;
348 void rand_cleanup_int(void)
350 const RAND_METHOD
*meth
= default_RAND_meth
;
352 rand_cleaning_up
= 1;
354 if (meth
!= NULL
&& meth
->cleanup
!= NULL
)
356 RAND_set_rand_method(NULL
);
358 #ifndef OPENSSL_NO_ENGINE
359 CRYPTO_THREAD_lock_free(rand_engine_lock
);
360 rand_engine_lock
= NULL
;
362 CRYPTO_THREAD_lock_free(rand_meth_lock
);
363 rand_meth_lock
= NULL
;
364 CRYPTO_THREAD_lock_free(rand_nonce_lock
);
365 rand_nonce_lock
= NULL
;
369 * RAND_close_seed_files() ensures that any seed file decriptors are
372 void RAND_keep_random_devices_open(int keep
)
374 rand_pool_keep_random_devices_open(keep
);
378 * RAND_poll() reseeds the default RNG using random input
380 * The random input is obtained from polling various entropy
381 * sources which depend on the operating system and are
382 * configurable via the --with-rand-seed configure option.
388 RAND_POOL
*pool
= NULL
;
390 const RAND_METHOD
*meth
= RAND_get_rand_method();
392 if (meth
== RAND_OpenSSL()) {
393 /* fill random pool and seed the master DRBG */
394 RAND_DRBG
*drbg
= RAND_DRBG_get0_master();
399 rand_drbg_lock(drbg
);
400 ret
= rand_drbg_restart(drbg
, NULL
, 0, 0);
401 rand_drbg_unlock(drbg
);
406 /* fill random pool and seed the current legacy RNG */
407 pool
= rand_pool_new(RAND_DRBG_STRENGTH
,
408 RAND_DRBG_STRENGTH
/ 8,
409 RAND_POOL_MAX_LENGTH
);
413 if (rand_pool_acquire_entropy(pool
) == 0)
416 if (meth
->add
== NULL
417 || meth
->add(rand_pool_buffer(pool
),
418 rand_pool_length(pool
),
419 (rand_pool_entropy(pool
) / 8.0)) == 0)
426 rand_pool_free(pool
);
431 * Allocate memory and initialize a new random pool
434 RAND_POOL
*rand_pool_new(int entropy_requested
, size_t min_len
, size_t max_len
)
436 RAND_POOL
*pool
= OPENSSL_zalloc(sizeof(*pool
));
439 RANDerr(RAND_F_RAND_POOL_NEW
, ERR_R_MALLOC_FAILURE
);
443 pool
->min_len
= min_len
;
444 pool
->max_len
= (max_len
> RAND_POOL_MAX_LENGTH
) ?
445 RAND_POOL_MAX_LENGTH
: max_len
;
447 pool
->buffer
= OPENSSL_secure_zalloc(pool
->max_len
);
448 if (pool
->buffer
== NULL
) {
449 RANDerr(RAND_F_RAND_POOL_NEW
, ERR_R_MALLOC_FAILURE
);
453 pool
->entropy_requested
= entropy_requested
;
463 * Attach new random pool to the given buffer
465 * This function is intended to be used only for feeding random data
466 * provided by RAND_add() and RAND_seed() into the <master> DRBG.
468 RAND_POOL
*rand_pool_attach(const unsigned char *buffer
, size_t len
,
471 RAND_POOL
*pool
= OPENSSL_zalloc(sizeof(*pool
));
474 RANDerr(RAND_F_RAND_POOL_ATTACH
, ERR_R_MALLOC_FAILURE
);
479 * The const needs to be cast away, but attached buffers will not be
480 * modified (in contrary to allocated buffers which are zeroed and
483 pool
->buffer
= (unsigned char *) buffer
;
488 pool
->min_len
= pool
->max_len
= pool
->len
;
489 pool
->entropy
= entropy
;
495 * Free |pool|, securely erasing its buffer.
497 void rand_pool_free(RAND_POOL
*pool
)
503 * Although it would be advisable from a cryptographical viewpoint,
504 * we are not allowed to clear attached buffers, since they are passed
505 * to rand_pool_attach() as `const unsigned char*`.
506 * (see corresponding comment in rand_pool_attach()).
509 OPENSSL_secure_clear_free(pool
->buffer
, pool
->max_len
);
514 * Return the |pool|'s buffer to the caller (readonly).
516 const unsigned char *rand_pool_buffer(RAND_POOL
*pool
)
522 * Return the |pool|'s entropy to the caller.
524 size_t rand_pool_entropy(RAND_POOL
*pool
)
526 return pool
->entropy
;
530 * Return the |pool|'s buffer length to the caller.
532 size_t rand_pool_length(RAND_POOL
*pool
)
538 * Detach the |pool| buffer and return it to the caller.
539 * It's the responsibility of the caller to free the buffer
540 * using OPENSSL_secure_clear_free().
542 unsigned char *rand_pool_detach(RAND_POOL
*pool
)
544 unsigned char *ret
= pool
->buffer
;
551 * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one
552 * need to obtain at least |bits| bits of entropy?
554 #define ENTROPY_TO_BYTES(bits, entropy_factor) \
555 (((bits) * (entropy_factor) + 7) / 8)
559 * Checks whether the |pool|'s entropy is available to the caller.
560 * This is the case when entropy count and buffer length are high enough.
563 * |entropy| if the entropy count and buffer size is large enough
566 size_t rand_pool_entropy_available(RAND_POOL
*pool
)
568 if (pool
->entropy
< pool
->entropy_requested
)
571 if (pool
->len
< pool
->min_len
)
574 return pool
->entropy
;
578 * Returns the (remaining) amount of entropy needed to fill
582 size_t rand_pool_entropy_needed(RAND_POOL
*pool
)
584 if (pool
->entropy
< pool
->entropy_requested
)
585 return pool
->entropy_requested
- pool
->entropy
;
591 * Returns the number of bytes needed to fill the pool, assuming
592 * the input has 1 / |entropy_factor| entropy bits per data bit.
593 * In case of an error, 0 is returned.
596 size_t rand_pool_bytes_needed(RAND_POOL
*pool
, unsigned int entropy_factor
)
599 size_t entropy_needed
= rand_pool_entropy_needed(pool
);
601 if (entropy_factor
< 1) {
602 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED
, RAND_R_ARGUMENT_OUT_OF_RANGE
);
606 bytes_needed
= ENTROPY_TO_BYTES(entropy_needed
, entropy_factor
);
608 if (bytes_needed
> pool
->max_len
- pool
->len
) {
609 /* not enough space left */
610 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED
, RAND_R_RANDOM_POOL_OVERFLOW
);
614 if (pool
->len
< pool
->min_len
&&
615 bytes_needed
< pool
->min_len
- pool
->len
)
616 /* to meet the min_len requirement */
617 bytes_needed
= pool
->min_len
- pool
->len
;
622 /* Returns the remaining number of bytes available */
623 size_t rand_pool_bytes_remaining(RAND_POOL
*pool
)
625 return pool
->max_len
- pool
->len
;
629 * Add random bytes to the random pool.
631 * It is expected that the |buffer| contains |len| bytes of
632 * random input which contains at least |entropy| bits of
635 * Returns 1 if the added amount is adequate, otherwise 0
637 int rand_pool_add(RAND_POOL
*pool
,
638 const unsigned char *buffer
, size_t len
, size_t entropy
)
640 if (len
> pool
->max_len
- pool
->len
) {
641 RANDerr(RAND_F_RAND_POOL_ADD
, RAND_R_ENTROPY_INPUT_TOO_LONG
);
646 memcpy(pool
->buffer
+ pool
->len
, buffer
, len
);
648 pool
->entropy
+= entropy
;
655 * Start to add random bytes to the random pool in-place.
657 * Reserves the next |len| bytes for adding random bytes in-place
658 * and returns a pointer to the buffer.
659 * The caller is allowed to copy up to |len| bytes into the buffer.
660 * If |len| == 0 this is considered a no-op and a NULL pointer
661 * is returned without producing an error message.
663 * After updating the buffer, rand_pool_add_end() needs to be called
664 * to finish the udpate operation (see next comment).
666 unsigned char *rand_pool_add_begin(RAND_POOL
*pool
, size_t len
)
671 if (len
> pool
->max_len
- pool
->len
) {
672 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN
, RAND_R_RANDOM_POOL_OVERFLOW
);
676 return pool
->buffer
+ pool
->len
;
680 * Finish to add random bytes to the random pool in-place.
682 * Finishes an in-place update of the random pool started by
683 * rand_pool_add_begin() (see previous comment).
684 * It is expected that |len| bytes of random input have been added
685 * to the buffer which contain at least |entropy| bits of randomness.
686 * It is allowed to add less bytes than originally reserved.
688 int rand_pool_add_end(RAND_POOL
*pool
, size_t len
, size_t entropy
)
690 if (len
> pool
->max_len
- pool
->len
) {
691 RANDerr(RAND_F_RAND_POOL_ADD_END
, RAND_R_RANDOM_POOL_OVERFLOW
);
697 pool
->entropy
+= entropy
;
703 int RAND_set_rand_method(const RAND_METHOD
*meth
)
705 if (!RUN_ONCE(&rand_init
, do_rand_init
))
708 CRYPTO_THREAD_write_lock(rand_meth_lock
);
709 #ifndef OPENSSL_NO_ENGINE
710 ENGINE_finish(funct_ref
);
713 default_RAND_meth
= meth
;
714 CRYPTO_THREAD_unlock(rand_meth_lock
);
718 const RAND_METHOD
*RAND_get_rand_method(void)
720 const RAND_METHOD
*tmp_meth
= NULL
;
722 if (!RUN_ONCE(&rand_init
, do_rand_init
))
725 CRYPTO_THREAD_write_lock(rand_meth_lock
);
726 if (default_RAND_meth
== NULL
) {
727 #ifndef OPENSSL_NO_ENGINE
730 /* If we have an engine that can do RAND, use it. */
731 if ((e
= ENGINE_get_default_RAND()) != NULL
732 && (tmp_meth
= ENGINE_get_RAND(e
)) != NULL
) {
734 default_RAND_meth
= tmp_meth
;
737 default_RAND_meth
= &rand_meth
;
740 default_RAND_meth
= &rand_meth
;
743 tmp_meth
= default_RAND_meth
;
744 CRYPTO_THREAD_unlock(rand_meth_lock
);
748 #ifndef OPENSSL_NO_ENGINE
749 int RAND_set_rand_engine(ENGINE
*engine
)
751 const RAND_METHOD
*tmp_meth
= NULL
;
753 if (!RUN_ONCE(&rand_init
, do_rand_init
))
756 if (engine
!= NULL
) {
757 if (!ENGINE_init(engine
))
759 tmp_meth
= ENGINE_get_RAND(engine
);
760 if (tmp_meth
== NULL
) {
761 ENGINE_finish(engine
);
765 CRYPTO_THREAD_write_lock(rand_engine_lock
);
766 /* This function releases any prior ENGINE so call it first */
767 RAND_set_rand_method(tmp_meth
);
769 CRYPTO_THREAD_unlock(rand_engine_lock
);
774 void RAND_seed(const void *buf
, int num
)
776 const RAND_METHOD
*meth
= RAND_get_rand_method();
778 if (meth
->seed
!= NULL
)
779 meth
->seed(buf
, num
);
782 void RAND_add(const void *buf
, int num
, double randomness
)
784 const RAND_METHOD
*meth
= RAND_get_rand_method();
786 if (meth
->add
!= NULL
)
787 meth
->add(buf
, num
, randomness
);
791 * This function is not part of RAND_METHOD, so if we're not using
792 * the default method, then just call RAND_bytes(). Otherwise make
793 * sure we're instantiated and use the private DRBG.
795 int RAND_priv_bytes(unsigned char *buf
, int num
)
797 const RAND_METHOD
*meth
= RAND_get_rand_method();
801 if (meth
!= RAND_OpenSSL())
802 return RAND_bytes(buf
, num
);
804 drbg
= RAND_DRBG_get0_private();
808 ret
= RAND_DRBG_bytes(drbg
, buf
, num
);
812 int RAND_bytes(unsigned char *buf
, int num
)
814 const RAND_METHOD
*meth
= RAND_get_rand_method();
816 if (meth
->bytes
!= NULL
)
817 return meth
->bytes(buf
, num
);
818 RANDerr(RAND_F_RAND_BYTES
, RAND_R_FUNC_NOT_IMPLEMENTED
);
822 #if OPENSSL_API_COMPAT < 0x10100000L
823 int RAND_pseudo_bytes(unsigned char *buf
, int num
)
825 const RAND_METHOD
*meth
= RAND_get_rand_method();
827 if (meth
->pseudorand
!= NULL
)
828 return meth
->pseudorand(buf
, num
);
833 int RAND_status(void)
835 const RAND_METHOD
*meth
= RAND_get_rand_method();
837 if (meth
->status
!= NULL
)
838 return meth
->status();