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
->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_cleaning_up
&& !rand_pool_init())
330 CRYPTO_THREAD_lock_free(rand_meth_lock
);
331 rand_meth_lock
= NULL
;
333 #ifndef OPENSSL_NO_ENGINE
334 CRYPTO_THREAD_lock_free(rand_engine_lock
);
335 rand_engine_lock
= NULL
;
340 void rand_cleanup_int(void)
342 const RAND_METHOD
*meth
= default_RAND_meth
;
344 rand_cleaning_up
= 1;
346 if (meth
!= NULL
&& meth
->cleanup
!= NULL
)
348 RAND_set_rand_method(NULL
);
350 #ifndef OPENSSL_NO_ENGINE
351 CRYPTO_THREAD_lock_free(rand_engine_lock
);
352 rand_engine_lock
= NULL
;
354 CRYPTO_THREAD_lock_free(rand_meth_lock
);
355 rand_meth_lock
= NULL
;
356 CRYPTO_THREAD_lock_free(rand_nonce_lock
);
357 rand_nonce_lock
= NULL
;
361 * RAND_close_seed_files() ensures that any seed file decriptors are
364 void RAND_keep_random_devices_open(int keep
)
366 rand_pool_keep_random_devices_open(keep
);
370 * RAND_poll() reseeds the default RNG using random input
372 * The random input is obtained from polling various entropy
373 * sources which depend on the operating system and are
374 * configurable via the --with-rand-seed configure option.
380 RAND_POOL
*pool
= NULL
;
382 const RAND_METHOD
*meth
= RAND_get_rand_method();
384 if (meth
== RAND_OpenSSL()) {
385 /* fill random pool and seed the master DRBG */
386 RAND_DRBG
*drbg
= RAND_DRBG_get0_master();
391 rand_drbg_lock(drbg
);
392 ret
= rand_drbg_restart(drbg
, NULL
, 0, 0);
393 rand_drbg_unlock(drbg
);
398 /* fill random pool and seed the current legacy RNG */
399 pool
= rand_pool_new(RAND_DRBG_STRENGTH
,
400 RAND_DRBG_STRENGTH
/ 8,
401 RAND_POOL_MAX_LENGTH
);
405 if (rand_pool_acquire_entropy(pool
) == 0)
408 if (meth
->add
== NULL
409 || meth
->add(rand_pool_buffer(pool
),
410 rand_pool_length(pool
),
411 (rand_pool_entropy(pool
) / 8.0)) == 0)
418 rand_pool_free(pool
);
423 * Allocate memory and initialize a new random pool
426 RAND_POOL
*rand_pool_new(int entropy_requested
, size_t min_len
, size_t max_len
)
428 RAND_POOL
*pool
= OPENSSL_zalloc(sizeof(*pool
));
431 RANDerr(RAND_F_RAND_POOL_NEW
, ERR_R_MALLOC_FAILURE
);
435 pool
->min_len
= min_len
;
436 pool
->max_len
= (max_len
> RAND_POOL_MAX_LENGTH
) ?
437 RAND_POOL_MAX_LENGTH
: max_len
;
439 pool
->buffer
= OPENSSL_secure_zalloc(pool
->max_len
);
440 if (pool
->buffer
== NULL
) {
441 RANDerr(RAND_F_RAND_POOL_NEW
, ERR_R_MALLOC_FAILURE
);
445 pool
->entropy_requested
= entropy_requested
;
455 * Attach new random pool to the given buffer
457 * This function is intended to be used only for feeding random data
458 * provided by RAND_add() and RAND_seed() into the <master> DRBG.
460 RAND_POOL
*rand_pool_attach(const unsigned char *buffer
, size_t len
,
463 RAND_POOL
*pool
= OPENSSL_zalloc(sizeof(*pool
));
466 RANDerr(RAND_F_RAND_POOL_ATTACH
, ERR_R_MALLOC_FAILURE
);
471 * The const needs to be cast away, but attached buffers will not be
472 * modified (in contrary to allocated buffers which are zeroed and
475 pool
->buffer
= (unsigned char *) buffer
;
480 pool
->min_len
= pool
->max_len
= pool
->len
;
481 pool
->entropy
= entropy
;
487 * Free |pool|, securely erasing its buffer.
489 void rand_pool_free(RAND_POOL
*pool
)
495 * Although it would be advisable from a cryptographical viewpoint,
496 * we are not allowed to clear attached buffers, since they are passed
497 * to rand_pool_attach() as `const unsigned char*`.
498 * (see corresponding comment in rand_pool_attach()).
501 OPENSSL_secure_clear_free(pool
->buffer
, pool
->max_len
);
506 * Return the |pool|'s buffer to the caller (readonly).
508 const unsigned char *rand_pool_buffer(RAND_POOL
*pool
)
514 * Return the |pool|'s entropy to the caller.
516 size_t rand_pool_entropy(RAND_POOL
*pool
)
518 return pool
->entropy
;
522 * Return the |pool|'s buffer length to the caller.
524 size_t rand_pool_length(RAND_POOL
*pool
)
530 * Detach the |pool| buffer and return it to the caller.
531 * It's the responsibility of the caller to free the buffer
532 * using OPENSSL_secure_clear_free() or to re-attach it
533 * again to the pool using rand_pool_reattach().
535 unsigned char *rand_pool_detach(RAND_POOL
*pool
)
537 unsigned char *ret
= pool
->buffer
;
544 * Re-attach the |pool| buffer. It is only allowed to pass
545 * the |buffer| which was previously detached from the same pool.
547 void rand_pool_reattach(RAND_POOL
*pool
, unsigned char *buffer
)
549 pool
->buffer
= buffer
;
550 OPENSSL_cleanse(pool
->buffer
, pool
->len
);
555 * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one
556 * need to obtain at least |bits| bits of entropy?
558 #define ENTROPY_TO_BYTES(bits, entropy_factor) \
559 (((bits) * (entropy_factor) + 7) / 8)
563 * Checks whether the |pool|'s entropy is available to the caller.
564 * This is the case when entropy count and buffer length are high enough.
567 * |entropy| if the entropy count and buffer size is large enough
570 size_t rand_pool_entropy_available(RAND_POOL
*pool
)
572 if (pool
->entropy
< pool
->entropy_requested
)
575 if (pool
->len
< pool
->min_len
)
578 return pool
->entropy
;
582 * Returns the (remaining) amount of entropy needed to fill
586 size_t rand_pool_entropy_needed(RAND_POOL
*pool
)
588 if (pool
->entropy
< pool
->entropy_requested
)
589 return pool
->entropy_requested
- pool
->entropy
;
595 * Returns the number of bytes needed to fill the pool, assuming
596 * the input has 1 / |entropy_factor| entropy bits per data bit.
597 * In case of an error, 0 is returned.
600 size_t rand_pool_bytes_needed(RAND_POOL
*pool
, unsigned int entropy_factor
)
603 size_t entropy_needed
= rand_pool_entropy_needed(pool
);
605 if (entropy_factor
< 1) {
606 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED
, RAND_R_ARGUMENT_OUT_OF_RANGE
);
610 bytes_needed
= ENTROPY_TO_BYTES(entropy_needed
, entropy_factor
);
612 if (bytes_needed
> pool
->max_len
- pool
->len
) {
613 /* not enough space left */
614 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED
, RAND_R_RANDOM_POOL_OVERFLOW
);
618 if (pool
->len
< pool
->min_len
&&
619 bytes_needed
< pool
->min_len
- pool
->len
)
620 /* to meet the min_len requirement */
621 bytes_needed
= pool
->min_len
- pool
->len
;
626 /* Returns the remaining number of bytes available */
627 size_t rand_pool_bytes_remaining(RAND_POOL
*pool
)
629 return pool
->max_len
- pool
->len
;
633 * Add random bytes to the random pool.
635 * It is expected that the |buffer| contains |len| bytes of
636 * random input which contains at least |entropy| bits of
639 * Returns 1 if the added amount is adequate, otherwise 0
641 int rand_pool_add(RAND_POOL
*pool
,
642 const unsigned char *buffer
, size_t len
, size_t entropy
)
644 if (len
> pool
->max_len
- pool
->len
) {
645 RANDerr(RAND_F_RAND_POOL_ADD
, RAND_R_ENTROPY_INPUT_TOO_LONG
);
649 if (pool
->buffer
== NULL
) {
650 RANDerr(RAND_F_RAND_POOL_ADD
, ERR_R_INTERNAL_ERROR
);
655 memcpy(pool
->buffer
+ pool
->len
, buffer
, len
);
657 pool
->entropy
+= entropy
;
664 * Start to add random bytes to the random pool in-place.
666 * Reserves the next |len| bytes for adding random bytes in-place
667 * and returns a pointer to the buffer.
668 * The caller is allowed to copy up to |len| bytes into the buffer.
669 * If |len| == 0 this is considered a no-op and a NULL pointer
670 * is returned without producing an error message.
672 * After updating the buffer, rand_pool_add_end() needs to be called
673 * to finish the udpate operation (see next comment).
675 unsigned char *rand_pool_add_begin(RAND_POOL
*pool
, size_t len
)
680 if (len
> pool
->max_len
- pool
->len
) {
681 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN
, RAND_R_RANDOM_POOL_OVERFLOW
);
685 if (pool
->buffer
== NULL
) {
686 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN
, ERR_R_INTERNAL_ERROR
);
690 return pool
->buffer
+ pool
->len
;
694 * Finish to add random bytes to the random pool in-place.
696 * Finishes an in-place update of the random pool started by
697 * rand_pool_add_begin() (see previous comment).
698 * It is expected that |len| bytes of random input have been added
699 * to the buffer which contain at least |entropy| bits of randomness.
700 * It is allowed to add less bytes than originally reserved.
702 int rand_pool_add_end(RAND_POOL
*pool
, size_t len
, size_t entropy
)
704 if (len
> pool
->max_len
- pool
->len
) {
705 RANDerr(RAND_F_RAND_POOL_ADD_END
, RAND_R_RANDOM_POOL_OVERFLOW
);
711 pool
->entropy
+= entropy
;
717 int RAND_set_rand_method(const RAND_METHOD
*meth
)
719 if (!RUN_ONCE(&rand_init
, do_rand_init
))
722 CRYPTO_THREAD_write_lock(rand_meth_lock
);
723 #ifndef OPENSSL_NO_ENGINE
724 ENGINE_finish(funct_ref
);
727 default_RAND_meth
= meth
;
728 CRYPTO_THREAD_unlock(rand_meth_lock
);
732 const RAND_METHOD
*RAND_get_rand_method(void)
734 const RAND_METHOD
*tmp_meth
= NULL
;
736 if (!RUN_ONCE(&rand_init
, do_rand_init
))
739 CRYPTO_THREAD_write_lock(rand_meth_lock
);
740 if (default_RAND_meth
== NULL
) {
741 #ifndef OPENSSL_NO_ENGINE
744 /* If we have an engine that can do RAND, use it. */
745 if ((e
= ENGINE_get_default_RAND()) != NULL
746 && (tmp_meth
= ENGINE_get_RAND(e
)) != NULL
) {
748 default_RAND_meth
= tmp_meth
;
751 default_RAND_meth
= &rand_meth
;
754 default_RAND_meth
= &rand_meth
;
757 tmp_meth
= default_RAND_meth
;
758 CRYPTO_THREAD_unlock(rand_meth_lock
);
762 #ifndef OPENSSL_NO_ENGINE
763 int RAND_set_rand_engine(ENGINE
*engine
)
765 const RAND_METHOD
*tmp_meth
= NULL
;
767 if (!RUN_ONCE(&rand_init
, do_rand_init
))
770 if (engine
!= NULL
) {
771 if (!ENGINE_init(engine
))
773 tmp_meth
= ENGINE_get_RAND(engine
);
774 if (tmp_meth
== NULL
) {
775 ENGINE_finish(engine
);
779 CRYPTO_THREAD_write_lock(rand_engine_lock
);
780 /* This function releases any prior ENGINE so call it first */
781 RAND_set_rand_method(tmp_meth
);
783 CRYPTO_THREAD_unlock(rand_engine_lock
);
788 void RAND_seed(const void *buf
, int num
)
790 const RAND_METHOD
*meth
= RAND_get_rand_method();
792 if (meth
->seed
!= NULL
)
793 meth
->seed(buf
, num
);
796 void RAND_add(const void *buf
, int num
, double randomness
)
798 const RAND_METHOD
*meth
= RAND_get_rand_method();
800 if (meth
->add
!= NULL
)
801 meth
->add(buf
, num
, randomness
);
805 * This function is not part of RAND_METHOD, so if we're not using
806 * the default method, then just call RAND_bytes(). Otherwise make
807 * sure we're instantiated and use the private DRBG.
809 int RAND_priv_bytes(unsigned char *buf
, int num
)
811 const RAND_METHOD
*meth
= RAND_get_rand_method();
815 if (meth
!= RAND_OpenSSL())
816 return RAND_bytes(buf
, num
);
818 drbg
= RAND_DRBG_get0_private();
822 ret
= RAND_DRBG_bytes(drbg
, buf
, num
);
826 int RAND_bytes(unsigned char *buf
, int num
)
828 const RAND_METHOD
*meth
= RAND_get_rand_method();
830 if (meth
->bytes
!= NULL
)
831 return meth
->bytes(buf
, num
);
832 RANDerr(RAND_F_RAND_BYTES
, RAND_R_FUNC_NOT_IMPLEMENTED
);
836 #if OPENSSL_API_COMPAT < 0x10100000L
837 int RAND_pseudo_bytes(unsigned char *buf
, int num
)
839 const RAND_METHOD
*meth
= RAND_get_rand_method();
841 if (meth
->pseudorand
!= NULL
)
842 return meth
->pseudorand(buf
, num
);
847 int RAND_status(void)
849 const RAND_METHOD
*meth
= RAND_get_rand_method();
851 if (meth
->status
!= NULL
)
852 return meth
->status();