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))
28 #ifndef OPENSSL_NO_ENGINE
29 /* non-NULL if default_RAND_meth is ENGINE-provided */
30 static ENGINE *funct_ref;
31 static CRYPTO_RWLOCK *rand_engine_lock;
33 static CRYPTO_RWLOCK *rand_meth_lock;
34 static const RAND_METHOD *default_RAND_meth;
35 static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT;
39 #ifdef OPENSSL_RAND_SEED_RDTSC
41 * IMPORTANT NOTE: It is not currently possible to use this code
42 * because we are not sure about the amount of randomness it provides.
43 * Some SP900 tests have been run, but there is internal skepticism.
44 * So for now this code is not used.
46 # error "RDTSC enabled? Should not be possible!"
49 * Acquire entropy from high-speed clock
51 * Since we get some randomness from the low-order bits of the
52 * high-speed clock, it can help.
54 * Returns the total entropy count, if it exceeds the requested
55 * entropy count. Otherwise, returns an entropy count of 0.
57 size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool)
62 if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) {
63 for (i = 0; i < TSC_READ_COUNT; i++) {
64 c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
65 RAND_POOL_add(pool, &c, 1, 4);
68 return RAND_POOL_entropy_available(pool);
72 #ifdef OPENSSL_RAND_SEED_RDCPU
73 size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf, size_t len);
74 size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf, size_t len);
76 extern unsigned int OPENSSL_ia32cap_P[];
79 * Acquire entropy using Intel-specific cpu instructions
81 * Uses the RDSEED instruction if available, otherwise uses
82 * RDRAND if available.
84 * For the differences between RDSEED and RDRAND, and why RDSEED
85 * is the preferred choice, see https://goo.gl/oK3KcN
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_cpu(RAND_POOL *pool)
93 unsigned char *buffer;
95 bytes_needed = RAND_POOL_bytes_needed(pool, 8 /*entropy_per_byte*/);
96 if (bytes_needed > 0) {
97 buffer = RAND_POOL_add_begin(pool, bytes_needed);
101 /* If RDSEED is available, use that. */
102 if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) {
103 if (OPENSSL_ia32_rdseed_bytes(buffer, bytes_needed)
105 return RAND_POOL_add_end(pool,
110 /* Second choice is RDRAND. */
111 if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
112 if (OPENSSL_ia32_rdrand_bytes(buffer, bytes_needed)
114 return RAND_POOL_add_end(pool,
119 return RAND_POOL_add_end(pool, 0, 0);
123 return RAND_POOL_entropy_available(pool);
129 * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())
131 * If the DRBG has a parent, then the required amount of entropy input
132 * is fetched using the parent's RAND_DRBG_generate().
134 * Otherwise, the entropy is polled from the system entropy sources
135 * using RAND_POOL_acquire_entropy().
137 * If a random pool has been added to the DRBG using RAND_add(), then
138 * its entropy will be used up first.
140 size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
141 unsigned char **pout,
142 int entropy, size_t min_len, size_t max_len)
145 size_t entropy_available = 0;
146 RAND_POOL *pool = RAND_POOL_new(entropy, min_len, max_len);
153 RAND_POOL_buffer(drbg->pool),
154 RAND_POOL_length(drbg->pool),
155 RAND_POOL_entropy(drbg->pool));
156 RAND_POOL_free(drbg->pool);
161 size_t bytes_needed = RAND_POOL_bytes_needed(pool, 8);
162 unsigned char *buffer = RAND_POOL_add_begin(pool, bytes_needed);
164 if (buffer != NULL) {
168 * Get random from parent, include our state as additional input.
169 * Our lock is already held, but we need to lock our parent before
170 * generating bits from it.
172 if (drbg->parent->lock)
173 CRYPTO_THREAD_write_lock(drbg->parent->lock);
174 if (RAND_DRBG_generate(drbg->parent,
175 buffer, bytes_needed,
177 (unsigned char *)drbg, sizeof(*drbg)) != 0)
178 bytes = bytes_needed;
179 if (drbg->parent->lock)
180 CRYPTO_THREAD_unlock(drbg->parent->lock);
182 entropy_available = RAND_POOL_add_end(pool, bytes, 8 * bytes);
186 /* Get entropy by polling system entropy sources. */
187 entropy_available = RAND_POOL_acquire_entropy(pool);
190 if (entropy_available > 0) {
191 ret = RAND_POOL_length(pool);
192 *pout = RAND_POOL_detach(pool);
195 RAND_POOL_free(pool);
200 * Find a suitable system time. Start with the highest resolution source
201 * and work down to the slower ones. This is added as additional data and
202 * isn't counted as randomness, so any result is acceptable.
204 static uint64_t get_timer_bits(void)
206 uint64_t res = OPENSSL_rdtsc();
215 if (QueryPerformanceCounter(&t) != 0)
217 GetSystemTimeAsFileTime(&ft);
218 return TWO32TO64(ft.dwHighDateTime, ft.dwLowDateTime);
220 #elif defined(__sun) || defined(__hpux)
226 read_wall_time(&t, TIMEBASE_SZ);
227 return TWO32TO64(t.tb_high, t.tb_low);
231 # if defined(_POSIX_C_SOURCE) \
232 && defined(_POSIX_TIMERS) \
233 && _POSIX_C_SOURCE >= 199309L \
234 && (!defined(__GLIBC__) || __GLIBC_PREREQ(2, 17))
239 # ifdef CLOCK_BOOTTIME
240 cid = CLOCK_BOOTTIME;
241 # elif defined(_POSIX_MONOTONIC_CLOCK)
242 cid = CLOCK_MONOTONIC;
244 cid = CLOCK_REALTIME;
247 if (clock_gettime(cid, &ts) == 0)
248 return TWO32TO64(ts.tv_sec, ts.tv_nsec);
251 # if defined(__unix__) \
252 || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
256 if (gettimeofday(&tv, NULL) == 0)
257 return TWO32TO64(tv.tv_sec, tv.tv_usec);
265 * Generate additional data that can be used for the drbg. The data does
266 * not need to contain entropy, but it's useful if it contains at least
267 * some bits that are unpredictable.
269 * Returns 0 on failure.
271 * On success it allocates a buffer at |*pout| and returns the length of
272 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
274 size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len)
277 CRYPTO_THREAD_ID thread_id;
279 #ifdef OPENSSL_SYS_UNIX
281 #elif defined(OPENSSL_SYS_WIN32)
286 pool = RAND_POOL_new(0, 0, max_len);
290 #ifdef OPENSSL_SYS_UNIX
292 RAND_POOL_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
293 #elif defined(OPENSSL_SYS_WIN32)
294 pid = GetCurrentProcessId();
295 RAND_POOL_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
298 thread_id = CRYPTO_THREAD_get_current_id();
300 RAND_POOL_add(pool, (unsigned char *)&thread_id, sizeof(thread_id), 0);
302 tbits = get_timer_bits();
303 RAND_POOL_add(pool, (unsigned char *)&tbits, sizeof(tbits), 0);
305 /* TODO: Use RDSEED? */
307 len = RAND_POOL_length(pool);
309 *pout = RAND_POOL_detach(pool);
310 RAND_POOL_free(pool);
316 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
319 void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
320 unsigned char *out, size_t outlen)
322 OPENSSL_secure_clear_free(out, outlen);
330 DEFINE_RUN_ONCE_STATIC(do_rand_init)
334 #ifndef OPENSSL_NO_ENGINE
335 rand_engine_lock = CRYPTO_THREAD_lock_new();
336 ret &= rand_engine_lock != NULL;
338 rand_meth_lock = CRYPTO_THREAD_lock_new();
339 ret &= rand_meth_lock != NULL;
344 void rand_cleanup_int(void)
346 const RAND_METHOD *meth = default_RAND_meth;
348 if (meth != NULL && meth->cleanup != NULL)
350 RAND_set_rand_method(NULL);
351 #ifndef OPENSSL_NO_ENGINE
352 CRYPTO_THREAD_lock_free(rand_engine_lock);
354 CRYPTO_THREAD_lock_free(rand_meth_lock);
358 * RAND_poll() reseeds the default RNG using random input
360 * The random input is obtained from polling various entropy
361 * sources which depend on the operating system and are
362 * configurable via the --with-rand-seed configure option.
368 RAND_POOL *pool = NULL;
370 const RAND_METHOD *meth = RAND_get_rand_method();
372 if (meth == RAND_OpenSSL()) {
373 /* fill random pool and seed the master DRBG */
374 RAND_DRBG *drbg = RAND_DRBG_get0_master();
379 CRYPTO_THREAD_write_lock(drbg->lock);
380 ret = rand_drbg_restart(drbg, NULL, 0, 0);
381 CRYPTO_THREAD_unlock(drbg->lock);
386 /* fill random pool and seed the current legacy RNG */
387 pool = RAND_POOL_new(RAND_DRBG_STRENGTH,
388 RAND_DRBG_STRENGTH / 8,
389 DRBG_MINMAX_FACTOR * (RAND_DRBG_STRENGTH / 8));
393 if (RAND_POOL_acquire_entropy(pool) == 0)
396 if (meth->add == NULL
397 || meth->add(RAND_POOL_buffer(pool),
398 RAND_POOL_length(pool),
399 (RAND_POOL_entropy(pool) / 8.0)) == 0)
406 RAND_POOL_free(pool);
411 * The 'random pool' acts as a dumb container for collecting random
412 * input from various entropy sources. The pool has no knowledge about
413 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
414 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
415 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
416 * 4) cleanup the random pool again.
418 * The random pool contains no locking mechanism because its scope and
419 * lifetime is intended to be restricted to a single stack frame.
421 struct rand_pool_st {
422 unsigned char *buffer; /* points to the beginning of the random pool */
423 size_t len; /* current number of random bytes contained in the pool */
425 size_t min_len; /* minimum number of random bytes requested */
426 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
427 size_t entropy; /* current entropy count in bits */
428 size_t requested_entropy; /* requested entropy count in bits */
432 * Allocate memory and initialize a new random pool
435 RAND_POOL *RAND_POOL_new(int entropy, size_t min_len, size_t max_len)
437 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
440 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
444 pool->min_len = min_len;
445 pool->max_len = 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->requested_entropy = entropy;
463 * Free |pool|, securely erasing its buffer.
465 void RAND_POOL_free(RAND_POOL *pool)
470 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
475 * Return the |pool|'s buffer to the caller (readonly).
477 const unsigned char *RAND_POOL_buffer(RAND_POOL *pool)
483 * Return the |pool|'s entropy to the caller.
485 size_t RAND_POOL_entropy(RAND_POOL *pool)
487 return pool->entropy;
491 * Return the |pool|'s buffer length to the caller.
493 size_t RAND_POOL_length(RAND_POOL *pool)
499 * Detach the |pool| buffer and return it to the caller.
500 * It's the responsibility of the caller to free the buffer
501 * using OPENSSL_secure_clear_free().
503 unsigned char *RAND_POOL_detach(RAND_POOL *pool)
505 unsigned char *ret = pool->buffer;
512 * If every byte of the input contains |entropy_per_bytes| bits of entropy,
513 * how many bytes does one need to obtain at least |bits| bits of entropy?
515 #define ENTROPY_TO_BYTES(bits, entropy_per_bytes) \
516 (((bits) + ((entropy_per_bytes) - 1))/(entropy_per_bytes))
520 * Checks whether the |pool|'s entropy is available to the caller.
521 * This is the case when entropy count and buffer length are high enough.
524 * |entropy| if the entropy count and buffer size is large enough
527 size_t RAND_POOL_entropy_available(RAND_POOL *pool)
529 if (pool->entropy < pool->requested_entropy)
532 if (pool->len < pool->min_len)
535 return pool->entropy;
539 * Returns the (remaining) amount of entropy needed to fill
543 size_t RAND_POOL_entropy_needed(RAND_POOL *pool)
545 if (pool->entropy < pool->requested_entropy)
546 return pool->requested_entropy - pool->entropy;
552 * Returns the number of bytes needed to fill the pool, assuming
553 * the input has 'entropy_per_byte' entropy bits per byte.
554 * In case of an error, 0 is returned.
557 size_t RAND_POOL_bytes_needed(RAND_POOL *pool, unsigned int entropy_per_byte)
560 size_t entropy_needed = RAND_POOL_entropy_needed(pool);
562 if (entropy_per_byte < 1 || entropy_per_byte > 8) {
563 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
567 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_per_byte);
569 if (bytes_needed > pool->max_len - pool->len) {
570 /* not enough space left */
571 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
575 if (pool->len < pool->min_len &&
576 bytes_needed < pool->min_len - pool->len)
577 /* to meet the min_len requirement */
578 bytes_needed = pool->min_len - pool->len;
583 /* Returns the remaining number of bytes available */
584 size_t RAND_POOL_bytes_remaining(RAND_POOL *pool)
586 return pool->max_len - pool->len;
590 * Add random bytes to the random pool.
592 * It is expected that the |buffer| contains |len| bytes of
593 * random input which contains at least |entropy| bits of
596 * Return available amount of entropy after this operation.
597 * (see RAND_POOL_entropy_available(pool))
599 size_t RAND_POOL_add(RAND_POOL *pool,
600 const unsigned char *buffer, size_t len, size_t entropy)
602 if (len > pool->max_len - pool->len) {
603 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
608 memcpy(pool->buffer + pool->len, buffer, len);
610 pool->entropy += entropy;
613 return RAND_POOL_entropy_available(pool);
617 * Start to add random bytes to the random pool in-place.
619 * Reserves the next |len| bytes for adding random bytes in-place
620 * and returns a pointer to the buffer.
621 * The caller is allowed to copy up to |len| bytes into the buffer.
622 * If |len| == 0 this is considered a no-op and a NULL pointer
623 * is returned without producing an error message.
625 * After updating the buffer, RAND_POOL_add_end() needs to be called
626 * to finish the udpate operation (see next comment).
628 unsigned char *RAND_POOL_add_begin(RAND_POOL *pool, size_t len)
633 if (len > pool->max_len - pool->len) {
634 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
638 return pool->buffer + pool->len;
642 * Finish to add random bytes to the random pool in-place.
644 * Finishes an in-place update of the random pool started by
645 * RAND_POOL_add_begin() (see previous comment).
646 * It is expected that |len| bytes of random input have been added
647 * to the buffer which contain at least |entropy| bits of randomness.
648 * It is allowed to add less bytes than originally reserved.
650 size_t RAND_POOL_add_end(RAND_POOL *pool, size_t len, size_t entropy)
652 if (len > pool->max_len - pool->len) {
653 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
659 pool->entropy += entropy;
662 return RAND_POOL_entropy_available(pool);
665 int RAND_set_rand_method(const RAND_METHOD *meth)
667 if (!RUN_ONCE(&rand_init, do_rand_init))
670 CRYPTO_THREAD_write_lock(rand_meth_lock);
671 #ifndef OPENSSL_NO_ENGINE
672 ENGINE_finish(funct_ref);
675 default_RAND_meth = meth;
676 CRYPTO_THREAD_unlock(rand_meth_lock);
680 const RAND_METHOD *RAND_get_rand_method(void)
682 const RAND_METHOD *tmp_meth = NULL;
684 if (!RUN_ONCE(&rand_init, do_rand_init))
687 CRYPTO_THREAD_write_lock(rand_meth_lock);
688 if (default_RAND_meth == NULL) {
689 #ifndef OPENSSL_NO_ENGINE
692 /* If we have an engine that can do RAND, use it. */
693 if ((e = ENGINE_get_default_RAND()) != NULL
694 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
696 default_RAND_meth = tmp_meth;
699 default_RAND_meth = &rand_meth;
702 default_RAND_meth = &rand_meth;
705 tmp_meth = default_RAND_meth;
706 CRYPTO_THREAD_unlock(rand_meth_lock);
710 #ifndef OPENSSL_NO_ENGINE
711 int RAND_set_rand_engine(ENGINE *engine)
713 const RAND_METHOD *tmp_meth = NULL;
715 if (!RUN_ONCE(&rand_init, do_rand_init))
718 if (engine != NULL) {
719 if (!ENGINE_init(engine))
721 tmp_meth = ENGINE_get_RAND(engine);
722 if (tmp_meth == NULL) {
723 ENGINE_finish(engine);
727 CRYPTO_THREAD_write_lock(rand_engine_lock);
728 /* This function releases any prior ENGINE so call it first */
729 RAND_set_rand_method(tmp_meth);
731 CRYPTO_THREAD_unlock(rand_engine_lock);
736 void RAND_seed(const void *buf, int num)
738 const RAND_METHOD *meth = RAND_get_rand_method();
740 if (meth->seed != NULL)
741 meth->seed(buf, num);
744 void RAND_add(const void *buf, int num, double randomness)
746 const RAND_METHOD *meth = RAND_get_rand_method();
748 if (meth->add != NULL)
749 meth->add(buf, num, randomness);
753 * This function is not part of RAND_METHOD, so if we're not using
754 * the default method, then just call RAND_bytes(). Otherwise make
755 * sure we're instantiated and use the private DRBG.
757 int RAND_priv_bytes(unsigned char *buf, int num)
759 const RAND_METHOD *meth = RAND_get_rand_method();
763 if (meth != RAND_OpenSSL())
764 return RAND_bytes(buf, num);
766 drbg = RAND_DRBG_get0_private();
770 /* We have to lock the DRBG before generating bits from it. */
771 CRYPTO_THREAD_write_lock(drbg->lock);
772 ret = RAND_DRBG_bytes(drbg, buf, num);
773 CRYPTO_THREAD_unlock(drbg->lock);
777 int RAND_bytes(unsigned char *buf, int num)
779 const RAND_METHOD *meth = RAND_get_rand_method();
781 if (meth->bytes != NULL)
782 return meth->bytes(buf, num);
783 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
787 #if OPENSSL_API_COMPAT < 0x10100000L
788 int RAND_pseudo_bytes(unsigned char *buf, int num)
790 const RAND_METHOD *meth = RAND_get_rand_method();
792 if (meth->pseudorand != NULL)
793 return meth->pseudorand(buf, num);
798 int RAND_status(void)
800 const RAND_METHOD *meth = RAND_get_rand_method();
802 if (meth->status != NULL)
803 return meth->status();