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"
18 #ifdef OPENSSL_SYS_UNIX
19 # include <sys/types.h>
21 # include <sys/time.h>
25 /* Macro to convert two thirty two bit values into a sixty four bit one */
26 #define TWO32TO64(a, b) ((((uint64_t)(a)) << 32) + (b))
29 * Check for the existence and support of POSIX timers. The standard
30 * says that the _POSIX_TIMERS macro will have a positive value if they
33 * However, we want an additional constraint: that the timer support does
34 * not require an extra library dependency. Early versions of glibc
35 * require -lrt to be specified on the link line to access the timers,
36 * so this needs to be checked for.
38 * It is worse because some libraries define __GLIBC__ but don't
39 * support the version testing macro (e.g. uClibc). This means
40 * an extra check is needed.
42 * The final condition is:
43 * "have posix timers and either not glibc or glibc without -lrt"
45 * The nested #if sequences are required to avoid using a parameterised
46 * macro that might be undefined.
48 #undef OSSL_POSIX_TIMER_OKAY
49 #if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
50 # if defined(__GLIBC__)
51 # if defined(__GLIBC_PREREQ)
52 # if __GLIBC_PREREQ(2, 17)
53 # define OSSL_POSIX_TIMER_OKAY
57 # define OSSL_POSIX_TIMER_OKAY
61 #ifndef OPENSSL_NO_ENGINE
62 /* non-NULL if default_RAND_meth is ENGINE-provided */
63 static ENGINE
*funct_ref
;
64 static CRYPTO_RWLOCK
*rand_engine_lock
;
66 static CRYPTO_RWLOCK
*rand_meth_lock
;
67 static const RAND_METHOD
*default_RAND_meth
;
68 static CRYPTO_ONCE rand_init
= CRYPTO_ONCE_STATIC_INIT
;
72 #ifdef OPENSSL_RAND_SEED_RDTSC
74 * IMPORTANT NOTE: It is not currently possible to use this code
75 * because we are not sure about the amount of randomness it provides.
76 * Some SP900 tests have been run, but there is internal skepticism.
77 * So for now this code is not used.
79 # error "RDTSC enabled? Should not be possible!"
82 * Acquire entropy from high-speed clock
84 * Since we get some randomness from the low-order bits of the
85 * high-speed clock, it can help.
87 * Returns the total entropy count, if it exceeds the requested
88 * entropy count. Otherwise, returns an entropy count of 0.
90 size_t rand_acquire_entropy_from_tsc(RAND_POOL
*pool
)
95 if ((OPENSSL_ia32cap_P
[0] & (1 << 4)) != 0) {
96 for (i
= 0; i
< TSC_READ_COUNT
; i
++) {
97 c
= (unsigned char)(OPENSSL_rdtsc() & 0xFF);
98 RAND_POOL_add(pool
, &c
, 1, 4);
101 return RAND_POOL_entropy_available(pool
);
105 #ifdef OPENSSL_RAND_SEED_RDCPU
106 size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf
, size_t len
);
107 size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf
, size_t len
);
109 extern unsigned int OPENSSL_ia32cap_P
[];
112 * Acquire entropy using Intel-specific cpu instructions
114 * Uses the RDSEED instruction if available, otherwise uses
115 * RDRAND if available.
117 * For the differences between RDSEED and RDRAND, and why RDSEED
118 * is the preferred choice, see https://goo.gl/oK3KcN
120 * Returns the total entropy count, if it exceeds the requested
121 * entropy count. Otherwise, returns an entropy count of 0.
123 size_t rand_acquire_entropy_from_cpu(RAND_POOL
*pool
)
126 unsigned char *buffer
;
128 bytes_needed
= RAND_POOL_bytes_needed(pool
, 8 /*entropy_per_byte*/);
129 if (bytes_needed
> 0) {
130 buffer
= RAND_POOL_add_begin(pool
, bytes_needed
);
132 if (buffer
!= NULL
) {
134 /* If RDSEED is available, use that. */
135 if ((OPENSSL_ia32cap_P
[2] & (1 << 18)) != 0) {
136 if (OPENSSL_ia32_rdseed_bytes(buffer
, bytes_needed
)
138 return RAND_POOL_add_end(pool
,
143 /* Second choice is RDRAND. */
144 if ((OPENSSL_ia32cap_P
[1] & (1 << (62 - 32))) != 0) {
145 if (OPENSSL_ia32_rdrand_bytes(buffer
, bytes_needed
)
147 return RAND_POOL_add_end(pool
,
152 return RAND_POOL_add_end(pool
, 0, 0);
156 return RAND_POOL_entropy_available(pool
);
162 * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())
164 * If the DRBG has a parent, then the required amount of entropy input
165 * is fetched using the parent's RAND_DRBG_generate().
167 * Otherwise, the entropy is polled from the system entropy sources
168 * using RAND_POOL_acquire_entropy().
170 * If a random pool has been added to the DRBG using RAND_add(), then
171 * its entropy will be used up first.
173 size_t rand_drbg_get_entropy(RAND_DRBG
*drbg
,
174 unsigned char **pout
,
175 int entropy
, size_t min_len
, size_t max_len
)
178 size_t entropy_available
= 0;
181 if (drbg
->parent
&& drbg
->strength
> drbg
->parent
->strength
) {
183 * We currently don't support the algorithm from NIST SP 800-90C
184 * 10.1.2 to use a weaker DRBG as source
186 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY
, RAND_R_PARENT_STRENGTH_TOO_WEAK
);
190 pool
= RAND_POOL_new(entropy
, min_len
, max_len
);
196 RAND_POOL_buffer(drbg
->pool
),
197 RAND_POOL_length(drbg
->pool
),
198 RAND_POOL_entropy(drbg
->pool
));
199 RAND_POOL_free(drbg
->pool
);
204 size_t bytes_needed
= RAND_POOL_bytes_needed(pool
, 8);
205 unsigned char *buffer
= RAND_POOL_add_begin(pool
, bytes_needed
);
207 if (buffer
!= NULL
) {
211 * Get random from parent, include our state as additional input.
212 * Our lock is already held, but we need to lock our parent before
213 * generating bits from it. (Note: taking the lock will be a no-op
214 * if locking if drbg->parent->lock == NULL.)
216 rand_drbg_lock(drbg
->parent
);
217 if (RAND_DRBG_generate(drbg
->parent
,
218 buffer
, bytes_needed
,
220 (unsigned char *)drbg
, sizeof(*drbg
)) != 0)
221 bytes
= bytes_needed
;
222 rand_drbg_unlock(drbg
->parent
);
224 entropy_available
= RAND_POOL_add_end(pool
, bytes
, 8 * bytes
);
228 /* Get entropy by polling system entropy sources. */
229 entropy_available
= RAND_POOL_acquire_entropy(pool
);
232 if (entropy_available
> 0) {
233 ret
= RAND_POOL_length(pool
);
234 *pout
= RAND_POOL_detach(pool
);
237 RAND_POOL_free(pool
);
242 * Find a suitable source of time. Start with the highest resolution source
243 * and work down to the slower ones. This is added as additional data and
244 * isn't counted as randomness, so any result is acceptable.
246 * Returns 0 when we weren't able to find any time source
248 static uint64_t get_timer_bits(void)
250 uint64_t res
= OPENSSL_rdtsc();
259 if (QueryPerformanceCounter(&t
) != 0)
261 GetSystemTimeAsFileTime(&ft
);
262 return TWO32TO64(ft
.dwHighDateTime
, ft
.dwLowDateTime
);
264 #elif defined(__sun) || defined(__hpux)
270 read_wall_time(&t
, TIMEBASE_SZ
);
271 return TWO32TO64(t
.tb_high
, t
.tb_low
);
275 # if defined(OSSL_POSIX_TIMER_OKAY)
280 # ifdef CLOCK_BOOTTIME
281 cid
= CLOCK_BOOTTIME
;
282 # elif defined(_POSIX_MONOTONIC_CLOCK)
283 cid
= CLOCK_MONOTONIC
;
285 cid
= CLOCK_REALTIME
;
288 if (clock_gettime(cid
, &ts
) == 0)
289 return TWO32TO64(ts
.tv_sec
, ts
.tv_nsec
);
292 # if defined(__unix__) \
293 || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
297 if (gettimeofday(&tv
, NULL
) == 0)
298 return TWO32TO64(tv
.tv_sec
, tv
.tv_usec
);
302 time_t t
= time(NULL
);
311 * Generate additional data that can be used for the drbg. The data does
312 * not need to contain entropy, but it's useful if it contains at least
313 * some bits that are unpredictable.
315 * Returns 0 on failure.
317 * On success it allocates a buffer at |*pout| and returns the length of
318 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
320 size_t rand_drbg_get_additional_data(unsigned char **pout
, size_t max_len
)
323 CRYPTO_THREAD_ID thread_id
;
325 #ifdef OPENSSL_SYS_UNIX
327 #elif defined(OPENSSL_SYS_WIN32)
332 pool
= RAND_POOL_new(0, 0, max_len
);
336 #ifdef OPENSSL_SYS_UNIX
338 RAND_POOL_add(pool
, (unsigned char *)&pid
, sizeof(pid
), 0);
339 #elif defined(OPENSSL_SYS_WIN32)
340 pid
= GetCurrentProcessId();
341 RAND_POOL_add(pool
, (unsigned char *)&pid
, sizeof(pid
), 0);
344 thread_id
= CRYPTO_THREAD_get_current_id();
346 RAND_POOL_add(pool
, (unsigned char *)&thread_id
, sizeof(thread_id
), 0);
348 tbits
= get_timer_bits();
350 RAND_POOL_add(pool
, (unsigned char *)&tbits
, sizeof(tbits
), 0);
352 /* TODO: Use RDSEED? */
354 len
= RAND_POOL_length(pool
);
356 *pout
= RAND_POOL_detach(pool
);
357 RAND_POOL_free(pool
);
363 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
366 void rand_drbg_cleanup_entropy(RAND_DRBG
*drbg
,
367 unsigned char *out
, size_t outlen
)
369 OPENSSL_secure_clear_free(out
, outlen
);
377 DEFINE_RUN_ONCE_STATIC(do_rand_init
)
381 #ifndef OPENSSL_NO_ENGINE
382 rand_engine_lock
= CRYPTO_THREAD_lock_new();
383 ret
&= rand_engine_lock
!= NULL
;
385 rand_meth_lock
= CRYPTO_THREAD_lock_new();
386 ret
&= rand_meth_lock
!= NULL
;
391 void rand_cleanup_int(void)
393 const RAND_METHOD
*meth
= default_RAND_meth
;
395 if (meth
!= NULL
&& meth
->cleanup
!= NULL
)
397 RAND_set_rand_method(NULL
);
398 #ifndef OPENSSL_NO_ENGINE
399 CRYPTO_THREAD_lock_free(rand_engine_lock
);
401 CRYPTO_THREAD_lock_free(rand_meth_lock
);
405 * RAND_poll() reseeds the default RNG using random input
407 * The random input is obtained from polling various entropy
408 * sources which depend on the operating system and are
409 * configurable via the --with-rand-seed configure option.
415 RAND_POOL
*pool
= NULL
;
417 const RAND_METHOD
*meth
= RAND_get_rand_method();
419 if (meth
== RAND_OpenSSL()) {
420 /* fill random pool and seed the master DRBG */
421 RAND_DRBG
*drbg
= RAND_DRBG_get0_master();
426 rand_drbg_lock(drbg
);
427 ret
= rand_drbg_restart(drbg
, NULL
, 0, 0);
428 rand_drbg_unlock(drbg
);
433 /* fill random pool and seed the current legacy RNG */
434 pool
= RAND_POOL_new(RAND_DRBG_STRENGTH
,
435 RAND_DRBG_STRENGTH
/ 8,
436 DRBG_MINMAX_FACTOR
* (RAND_DRBG_STRENGTH
/ 8));
440 if (RAND_POOL_acquire_entropy(pool
) == 0)
443 if (meth
->add
== NULL
444 || meth
->add(RAND_POOL_buffer(pool
),
445 RAND_POOL_length(pool
),
446 (RAND_POOL_entropy(pool
) / 8.0)) == 0)
453 RAND_POOL_free(pool
);
458 * The 'random pool' acts as a dumb container for collecting random
459 * input from various entropy sources. The pool has no knowledge about
460 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
461 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
462 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
463 * 4) cleanup the random pool again.
465 * The random pool contains no locking mechanism because its scope and
466 * lifetime is intended to be restricted to a single stack frame.
468 struct rand_pool_st
{
469 unsigned char *buffer
; /* points to the beginning of the random pool */
470 size_t len
; /* current number of random bytes contained in the pool */
472 size_t min_len
; /* minimum number of random bytes requested */
473 size_t max_len
; /* maximum number of random bytes (allocated buffer size) */
474 size_t entropy
; /* current entropy count in bits */
475 size_t requested_entropy
; /* requested entropy count in bits */
479 * Allocate memory and initialize a new random pool
482 RAND_POOL
*RAND_POOL_new(int entropy
, size_t min_len
, size_t max_len
)
484 RAND_POOL
*pool
= OPENSSL_zalloc(sizeof(*pool
));
487 RANDerr(RAND_F_RAND_POOL_NEW
, ERR_R_MALLOC_FAILURE
);
491 pool
->min_len
= min_len
;
492 pool
->max_len
= max_len
;
494 pool
->buffer
= OPENSSL_secure_zalloc(pool
->max_len
);
495 if (pool
->buffer
== NULL
) {
496 RANDerr(RAND_F_RAND_POOL_NEW
, ERR_R_MALLOC_FAILURE
);
500 pool
->requested_entropy
= entropy
;
510 * Free |pool|, securely erasing its buffer.
512 void RAND_POOL_free(RAND_POOL
*pool
)
517 OPENSSL_secure_clear_free(pool
->buffer
, pool
->max_len
);
522 * Return the |pool|'s buffer to the caller (readonly).
524 const unsigned char *RAND_POOL_buffer(RAND_POOL
*pool
)
530 * Return the |pool|'s entropy to the caller.
532 size_t RAND_POOL_entropy(RAND_POOL
*pool
)
534 return pool
->entropy
;
538 * Return the |pool|'s buffer length to the caller.
540 size_t RAND_POOL_length(RAND_POOL
*pool
)
546 * Detach the |pool| buffer and return it to the caller.
547 * It's the responsibility of the caller to free the buffer
548 * using OPENSSL_secure_clear_free().
550 unsigned char *RAND_POOL_detach(RAND_POOL
*pool
)
552 unsigned char *ret
= pool
->buffer
;
559 * If every byte of the input contains |entropy_per_bytes| bits of entropy,
560 * how many bytes does one need to obtain at least |bits| bits of entropy?
562 #define ENTROPY_TO_BYTES(bits, entropy_per_bytes) \
563 (((bits) + ((entropy_per_bytes) - 1))/(entropy_per_bytes))
567 * Checks whether the |pool|'s entropy is available to the caller.
568 * This is the case when entropy count and buffer length are high enough.
571 * |entropy| if the entropy count and buffer size is large enough
574 size_t RAND_POOL_entropy_available(RAND_POOL
*pool
)
576 if (pool
->entropy
< pool
->requested_entropy
)
579 if (pool
->len
< pool
->min_len
)
582 return pool
->entropy
;
586 * Returns the (remaining) amount of entropy needed to fill
590 size_t RAND_POOL_entropy_needed(RAND_POOL
*pool
)
592 if (pool
->entropy
< pool
->requested_entropy
)
593 return pool
->requested_entropy
- pool
->entropy
;
599 * Returns the number of bytes needed to fill the pool, assuming
600 * the input has 'entropy_per_byte' entropy bits per byte.
601 * In case of an error, 0 is returned.
604 size_t RAND_POOL_bytes_needed(RAND_POOL
*pool
, unsigned int entropy_per_byte
)
607 size_t entropy_needed
= RAND_POOL_entropy_needed(pool
);
609 if (entropy_per_byte
< 1 || entropy_per_byte
> 8) {
610 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED
, RAND_R_ARGUMENT_OUT_OF_RANGE
);
614 bytes_needed
= ENTROPY_TO_BYTES(entropy_needed
, entropy_per_byte
);
616 if (bytes_needed
> pool
->max_len
- pool
->len
) {
617 /* not enough space left */
618 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED
, RAND_R_RANDOM_POOL_OVERFLOW
);
622 if (pool
->len
< pool
->min_len
&&
623 bytes_needed
< pool
->min_len
- pool
->len
)
624 /* to meet the min_len requirement */
625 bytes_needed
= pool
->min_len
- pool
->len
;
630 /* Returns the remaining number of bytes available */
631 size_t RAND_POOL_bytes_remaining(RAND_POOL
*pool
)
633 return pool
->max_len
- pool
->len
;
637 * Add random bytes to the random pool.
639 * It is expected that the |buffer| contains |len| bytes of
640 * random input which contains at least |entropy| bits of
643 * Return available amount of entropy after this operation.
644 * (see RAND_POOL_entropy_available(pool))
646 size_t 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
);
655 memcpy(pool
->buffer
+ pool
->len
, buffer
, len
);
657 pool
->entropy
+= entropy
;
660 return RAND_POOL_entropy_available(pool
);
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 return pool
->buffer
+ pool
->len
;
689 * Finish to add random bytes to the random pool in-place.
691 * Finishes an in-place update of the random pool started by
692 * RAND_POOL_add_begin() (see previous comment).
693 * It is expected that |len| bytes of random input have been added
694 * to the buffer which contain at least |entropy| bits of randomness.
695 * It is allowed to add less bytes than originally reserved.
697 size_t RAND_POOL_add_end(RAND_POOL
*pool
, size_t len
, size_t entropy
)
699 if (len
> pool
->max_len
- pool
->len
) {
700 RANDerr(RAND_F_RAND_POOL_ADD_END
, RAND_R_RANDOM_POOL_OVERFLOW
);
706 pool
->entropy
+= entropy
;
709 return RAND_POOL_entropy_available(pool
);
712 int RAND_set_rand_method(const RAND_METHOD
*meth
)
714 if (!RUN_ONCE(&rand_init
, do_rand_init
))
717 CRYPTO_THREAD_write_lock(rand_meth_lock
);
718 #ifndef OPENSSL_NO_ENGINE
719 ENGINE_finish(funct_ref
);
722 default_RAND_meth
= meth
;
723 CRYPTO_THREAD_unlock(rand_meth_lock
);
727 const RAND_METHOD
*RAND_get_rand_method(void)
729 const RAND_METHOD
*tmp_meth
= NULL
;
731 if (!RUN_ONCE(&rand_init
, do_rand_init
))
734 CRYPTO_THREAD_write_lock(rand_meth_lock
);
735 if (default_RAND_meth
== NULL
) {
736 #ifndef OPENSSL_NO_ENGINE
739 /* If we have an engine that can do RAND, use it. */
740 if ((e
= ENGINE_get_default_RAND()) != NULL
741 && (tmp_meth
= ENGINE_get_RAND(e
)) != NULL
) {
743 default_RAND_meth
= tmp_meth
;
746 default_RAND_meth
= &rand_meth
;
749 default_RAND_meth
= &rand_meth
;
752 tmp_meth
= default_RAND_meth
;
753 CRYPTO_THREAD_unlock(rand_meth_lock
);
757 #ifndef OPENSSL_NO_ENGINE
758 int RAND_set_rand_engine(ENGINE
*engine
)
760 const RAND_METHOD
*tmp_meth
= NULL
;
762 if (!RUN_ONCE(&rand_init
, do_rand_init
))
765 if (engine
!= NULL
) {
766 if (!ENGINE_init(engine
))
768 tmp_meth
= ENGINE_get_RAND(engine
);
769 if (tmp_meth
== NULL
) {
770 ENGINE_finish(engine
);
774 CRYPTO_THREAD_write_lock(rand_engine_lock
);
775 /* This function releases any prior ENGINE so call it first */
776 RAND_set_rand_method(tmp_meth
);
778 CRYPTO_THREAD_unlock(rand_engine_lock
);
783 void RAND_seed(const void *buf
, int num
)
785 const RAND_METHOD
*meth
= RAND_get_rand_method();
787 if (meth
->seed
!= NULL
)
788 meth
->seed(buf
, num
);
791 void RAND_add(const void *buf
, int num
, double randomness
)
793 const RAND_METHOD
*meth
= RAND_get_rand_method();
795 if (meth
->add
!= NULL
)
796 meth
->add(buf
, num
, randomness
);
800 * This function is not part of RAND_METHOD, so if we're not using
801 * the default method, then just call RAND_bytes(). Otherwise make
802 * sure we're instantiated and use the private DRBG.
804 int RAND_priv_bytes(unsigned char *buf
, int num
)
806 const RAND_METHOD
*meth
= RAND_get_rand_method();
810 if (meth
!= RAND_OpenSSL())
811 return RAND_bytes(buf
, num
);
813 drbg
= RAND_DRBG_get0_private();
817 /* We have to lock the DRBG before generating bits from it. */
818 rand_drbg_lock(drbg
);
819 ret
= RAND_DRBG_bytes(drbg
, buf
, num
);
820 rand_drbg_unlock(drbg
);
824 int RAND_bytes(unsigned char *buf
, int num
)
826 const RAND_METHOD
*meth
= RAND_get_rand_method();
828 if (meth
->bytes
!= NULL
)
829 return meth
->bytes(buf
, num
);
830 RANDerr(RAND_F_RAND_BYTES
, RAND_R_FUNC_NOT_IMPLEMENTED
);
834 #if OPENSSL_API_COMPAT < 0x10100000L
835 int RAND_pseudo_bytes(unsigned char *buf
, int num
)
837 const RAND_METHOD
*meth
= RAND_get_rand_method();
839 if (meth
->pseudorand
!= NULL
)
840 return meth
->pseudorand(buf
, num
);
845 int RAND_status(void)
847 const RAND_METHOD
*meth
= RAND_get_rand_method();
849 if (meth
->status
!= NULL
)
850 return meth
->status();