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;
179 RAND_POOL *pool = RAND_POOL_new(entropy, min_len, max_len);
186 RAND_POOL_buffer(drbg->pool),
187 RAND_POOL_length(drbg->pool),
188 RAND_POOL_entropy(drbg->pool));
189 RAND_POOL_free(drbg->pool);
194 size_t bytes_needed = RAND_POOL_bytes_needed(pool, 8);
195 unsigned char *buffer = RAND_POOL_add_begin(pool, bytes_needed);
197 if (buffer != NULL) {
201 * Get random from parent, include our state as additional input.
202 * Our lock is already held, but we need to lock our parent before
203 * generating bits from it. (Note: taking the lock will be a no-op
204 * if locking if drbg->parent->lock == NULL.)
206 rand_drbg_lock(drbg->parent);
207 if (RAND_DRBG_generate(drbg->parent,
208 buffer, bytes_needed,
210 (unsigned char *)drbg, sizeof(*drbg)) != 0)
211 bytes = bytes_needed;
212 rand_drbg_unlock(drbg->parent);
214 entropy_available = RAND_POOL_add_end(pool, bytes, 8 * bytes);
218 /* Get entropy by polling system entropy sources. */
219 entropy_available = RAND_POOL_acquire_entropy(pool);
222 if (entropy_available > 0) {
223 ret = RAND_POOL_length(pool);
224 *pout = RAND_POOL_detach(pool);
227 RAND_POOL_free(pool);
232 * Find a suitable system time. Start with the highest resolution source
233 * and work down to the slower ones. This is added as additional data and
234 * isn't counted as randomness, so any result is acceptable.
236 static uint64_t get_timer_bits(void)
238 uint64_t res = OPENSSL_rdtsc();
247 if (QueryPerformanceCounter(&t) != 0)
249 GetSystemTimeAsFileTime(&ft);
250 return TWO32TO64(ft.dwHighDateTime, ft.dwLowDateTime);
252 #elif defined(__sun) || defined(__hpux)
258 read_wall_time(&t, TIMEBASE_SZ);
259 return TWO32TO64(t.tb_high, t.tb_low);
263 #if defined(OSSL_POSIX_TIMER_OKAY)
268 # ifdef CLOCK_BOOTTIME
269 cid = CLOCK_BOOTTIME;
270 # elif defined(_POSIX_MONOTONIC_CLOCK)
271 cid = CLOCK_MONOTONIC;
273 cid = CLOCK_REALTIME;
276 if (clock_gettime(cid, &ts) == 0)
277 return TWO32TO64(ts.tv_sec, ts.tv_nsec);
280 # if defined(__unix__) \
281 || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
285 if (gettimeofday(&tv, NULL) == 0)
286 return TWO32TO64(tv.tv_sec, tv.tv_usec);
294 * Generate additional data that can be used for the drbg. The data does
295 * not need to contain entropy, but it's useful if it contains at least
296 * some bits that are unpredictable.
298 * Returns 0 on failure.
300 * On success it allocates a buffer at |*pout| and returns the length of
301 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
303 size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len)
306 CRYPTO_THREAD_ID thread_id;
308 #ifdef OPENSSL_SYS_UNIX
310 #elif defined(OPENSSL_SYS_WIN32)
315 pool = RAND_POOL_new(0, 0, max_len);
319 #ifdef OPENSSL_SYS_UNIX
321 RAND_POOL_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
322 #elif defined(OPENSSL_SYS_WIN32)
323 pid = GetCurrentProcessId();
324 RAND_POOL_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
327 thread_id = CRYPTO_THREAD_get_current_id();
329 RAND_POOL_add(pool, (unsigned char *)&thread_id, sizeof(thread_id), 0);
331 tbits = get_timer_bits();
332 RAND_POOL_add(pool, (unsigned char *)&tbits, sizeof(tbits), 0);
334 /* TODO: Use RDSEED? */
336 len = RAND_POOL_length(pool);
338 *pout = RAND_POOL_detach(pool);
339 RAND_POOL_free(pool);
345 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
348 void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
349 unsigned char *out, size_t outlen)
351 OPENSSL_secure_clear_free(out, outlen);
359 DEFINE_RUN_ONCE_STATIC(do_rand_init)
363 #ifndef OPENSSL_NO_ENGINE
364 rand_engine_lock = CRYPTO_THREAD_lock_new();
365 ret &= rand_engine_lock != NULL;
367 rand_meth_lock = CRYPTO_THREAD_lock_new();
368 ret &= rand_meth_lock != NULL;
373 void rand_cleanup_int(void)
375 const RAND_METHOD *meth = default_RAND_meth;
377 if (meth != NULL && meth->cleanup != NULL)
379 RAND_set_rand_method(NULL);
380 #ifndef OPENSSL_NO_ENGINE
381 CRYPTO_THREAD_lock_free(rand_engine_lock);
383 CRYPTO_THREAD_lock_free(rand_meth_lock);
387 * RAND_poll() reseeds the default RNG using random input
389 * The random input is obtained from polling various entropy
390 * sources which depend on the operating system and are
391 * configurable via the --with-rand-seed configure option.
397 RAND_POOL *pool = NULL;
399 const RAND_METHOD *meth = RAND_get_rand_method();
401 if (meth == RAND_OpenSSL()) {
402 /* fill random pool and seed the master DRBG */
403 RAND_DRBG *drbg = RAND_DRBG_get0_master();
408 rand_drbg_lock(drbg);
409 ret = rand_drbg_restart(drbg, NULL, 0, 0);
410 rand_drbg_unlock(drbg);
415 /* fill random pool and seed the current legacy RNG */
416 pool = RAND_POOL_new(RAND_DRBG_STRENGTH,
417 RAND_DRBG_STRENGTH / 8,
418 DRBG_MINMAX_FACTOR * (RAND_DRBG_STRENGTH / 8));
422 if (RAND_POOL_acquire_entropy(pool) == 0)
425 if (meth->add == NULL
426 || meth->add(RAND_POOL_buffer(pool),
427 RAND_POOL_length(pool),
428 (RAND_POOL_entropy(pool) / 8.0)) == 0)
435 RAND_POOL_free(pool);
440 * The 'random pool' acts as a dumb container for collecting random
441 * input from various entropy sources. The pool has no knowledge about
442 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
443 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
444 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
445 * 4) cleanup the random pool again.
447 * The random pool contains no locking mechanism because its scope and
448 * lifetime is intended to be restricted to a single stack frame.
450 struct rand_pool_st {
451 unsigned char *buffer; /* points to the beginning of the random pool */
452 size_t len; /* current number of random bytes contained in the pool */
454 size_t min_len; /* minimum number of random bytes requested */
455 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
456 size_t entropy; /* current entropy count in bits */
457 size_t requested_entropy; /* requested entropy count in bits */
461 * Allocate memory and initialize a new random pool
464 RAND_POOL *RAND_POOL_new(int entropy, size_t min_len, size_t max_len)
466 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
469 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
473 pool->min_len = min_len;
474 pool->max_len = max_len;
476 pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
477 if (pool->buffer == NULL) {
478 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
482 pool->requested_entropy = entropy;
492 * Free |pool|, securely erasing its buffer.
494 void RAND_POOL_free(RAND_POOL *pool)
499 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
504 * Return the |pool|'s buffer to the caller (readonly).
506 const unsigned char *RAND_POOL_buffer(RAND_POOL *pool)
512 * Return the |pool|'s entropy to the caller.
514 size_t RAND_POOL_entropy(RAND_POOL *pool)
516 return pool->entropy;
520 * Return the |pool|'s buffer length to the caller.
522 size_t RAND_POOL_length(RAND_POOL *pool)
528 * Detach the |pool| buffer and return it to the caller.
529 * It's the responsibility of the caller to free the buffer
530 * using OPENSSL_secure_clear_free().
532 unsigned char *RAND_POOL_detach(RAND_POOL *pool)
534 unsigned char *ret = pool->buffer;
541 * If every byte of the input contains |entropy_per_bytes| bits of entropy,
542 * how many bytes does one need to obtain at least |bits| bits of entropy?
544 #define ENTROPY_TO_BYTES(bits, entropy_per_bytes) \
545 (((bits) + ((entropy_per_bytes) - 1))/(entropy_per_bytes))
549 * Checks whether the |pool|'s entropy is available to the caller.
550 * This is the case when entropy count and buffer length are high enough.
553 * |entropy| if the entropy count and buffer size is large enough
556 size_t RAND_POOL_entropy_available(RAND_POOL *pool)
558 if (pool->entropy < pool->requested_entropy)
561 if (pool->len < pool->min_len)
564 return pool->entropy;
568 * Returns the (remaining) amount of entropy needed to fill
572 size_t RAND_POOL_entropy_needed(RAND_POOL *pool)
574 if (pool->entropy < pool->requested_entropy)
575 return pool->requested_entropy - pool->entropy;
581 * Returns the number of bytes needed to fill the pool, assuming
582 * the input has 'entropy_per_byte' entropy bits per byte.
583 * In case of an error, 0 is returned.
586 size_t RAND_POOL_bytes_needed(RAND_POOL *pool, unsigned int entropy_per_byte)
589 size_t entropy_needed = RAND_POOL_entropy_needed(pool);
591 if (entropy_per_byte < 1 || entropy_per_byte > 8) {
592 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
596 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_per_byte);
598 if (bytes_needed > pool->max_len - pool->len) {
599 /* not enough space left */
600 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
604 if (pool->len < pool->min_len &&
605 bytes_needed < pool->min_len - pool->len)
606 /* to meet the min_len requirement */
607 bytes_needed = pool->min_len - pool->len;
612 /* Returns the remaining number of bytes available */
613 size_t RAND_POOL_bytes_remaining(RAND_POOL *pool)
615 return pool->max_len - pool->len;
619 * Add random bytes to the random pool.
621 * It is expected that the |buffer| contains |len| bytes of
622 * random input which contains at least |entropy| bits of
625 * Return available amount of entropy after this operation.
626 * (see RAND_POOL_entropy_available(pool))
628 size_t RAND_POOL_add(RAND_POOL *pool,
629 const unsigned char *buffer, size_t len, size_t entropy)
631 if (len > pool->max_len - pool->len) {
632 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
637 memcpy(pool->buffer + pool->len, buffer, len);
639 pool->entropy += entropy;
642 return RAND_POOL_entropy_available(pool);
646 * Start to add random bytes to the random pool in-place.
648 * Reserves the next |len| bytes for adding random bytes in-place
649 * and returns a pointer to the buffer.
650 * The caller is allowed to copy up to |len| bytes into the buffer.
651 * If |len| == 0 this is considered a no-op and a NULL pointer
652 * is returned without producing an error message.
654 * After updating the buffer, RAND_POOL_add_end() needs to be called
655 * to finish the udpate operation (see next comment).
657 unsigned char *RAND_POOL_add_begin(RAND_POOL *pool, size_t len)
662 if (len > pool->max_len - pool->len) {
663 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
667 return pool->buffer + pool->len;
671 * Finish to add random bytes to the random pool in-place.
673 * Finishes an in-place update of the random pool started by
674 * RAND_POOL_add_begin() (see previous comment).
675 * It is expected that |len| bytes of random input have been added
676 * to the buffer which contain at least |entropy| bits of randomness.
677 * It is allowed to add less bytes than originally reserved.
679 size_t RAND_POOL_add_end(RAND_POOL *pool, size_t len, size_t entropy)
681 if (len > pool->max_len - pool->len) {
682 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
688 pool->entropy += entropy;
691 return RAND_POOL_entropy_available(pool);
694 int RAND_set_rand_method(const RAND_METHOD *meth)
696 if (!RUN_ONCE(&rand_init, do_rand_init))
699 CRYPTO_THREAD_write_lock(rand_meth_lock);
700 #ifndef OPENSSL_NO_ENGINE
701 ENGINE_finish(funct_ref);
704 default_RAND_meth = meth;
705 CRYPTO_THREAD_unlock(rand_meth_lock);
709 const RAND_METHOD *RAND_get_rand_method(void)
711 const RAND_METHOD *tmp_meth = NULL;
713 if (!RUN_ONCE(&rand_init, do_rand_init))
716 CRYPTO_THREAD_write_lock(rand_meth_lock);
717 if (default_RAND_meth == NULL) {
718 #ifndef OPENSSL_NO_ENGINE
721 /* If we have an engine that can do RAND, use it. */
722 if ((e = ENGINE_get_default_RAND()) != NULL
723 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
725 default_RAND_meth = tmp_meth;
728 default_RAND_meth = &rand_meth;
731 default_RAND_meth = &rand_meth;
734 tmp_meth = default_RAND_meth;
735 CRYPTO_THREAD_unlock(rand_meth_lock);
739 #ifndef OPENSSL_NO_ENGINE
740 int RAND_set_rand_engine(ENGINE *engine)
742 const RAND_METHOD *tmp_meth = NULL;
744 if (!RUN_ONCE(&rand_init, do_rand_init))
747 if (engine != NULL) {
748 if (!ENGINE_init(engine))
750 tmp_meth = ENGINE_get_RAND(engine);
751 if (tmp_meth == NULL) {
752 ENGINE_finish(engine);
756 CRYPTO_THREAD_write_lock(rand_engine_lock);
757 /* This function releases any prior ENGINE so call it first */
758 RAND_set_rand_method(tmp_meth);
760 CRYPTO_THREAD_unlock(rand_engine_lock);
765 void RAND_seed(const void *buf, int num)
767 const RAND_METHOD *meth = RAND_get_rand_method();
769 if (meth->seed != NULL)
770 meth->seed(buf, num);
773 void RAND_add(const void *buf, int num, double randomness)
775 const RAND_METHOD *meth = RAND_get_rand_method();
777 if (meth->add != NULL)
778 meth->add(buf, num, randomness);
782 * This function is not part of RAND_METHOD, so if we're not using
783 * the default method, then just call RAND_bytes(). Otherwise make
784 * sure we're instantiated and use the private DRBG.
786 int RAND_priv_bytes(unsigned char *buf, int num)
788 const RAND_METHOD *meth = RAND_get_rand_method();
792 if (meth != RAND_OpenSSL())
793 return RAND_bytes(buf, num);
795 drbg = RAND_DRBG_get0_private();
799 /* We have to lock the DRBG before generating bits from it. */
800 rand_drbg_lock(drbg);
801 ret = RAND_DRBG_bytes(drbg, buf, num);
802 rand_drbg_unlock(drbg);
806 int RAND_bytes(unsigned char *buf, int num)
808 const RAND_METHOD *meth = RAND_get_rand_method();
810 if (meth->bytes != NULL)
811 return meth->bytes(buf, num);
812 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
816 #if OPENSSL_API_COMPAT < 0x10100000L
817 int RAND_pseudo_bytes(unsigned char *buf, int num)
819 const RAND_METHOD *meth = RAND_get_rand_method();
821 if (meth->pseudorand != NULL)
822 return meth->pseudorand(buf, num);
827 int RAND_status(void)
829 const RAND_METHOD *meth = RAND_get_rand_method();
831 if (meth->status != NULL)
832 return meth->status();