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 #ifdef OPENSSL_RAND_SEED_RDTSC
36 * IMPORTANT NOTE: It is not currently possible to use this code
37 * because we are not sure about the amount of randomness it provides.
38 * Some SP900 tests have been run, but there is internal skepticism.
39 * So for now this code is not used.
41 # error "RDTSC enabled? Should not be possible!"
44 * Acquire entropy from high-speed clock
46 * Since we get some randomness from the low-order bits of the
47 * high-speed clock, it can help.
49 * Returns the total entropy count, if it exceeds the requested
50 * entropy count. Otherwise, returns an entropy count of 0.
52 size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool)
57 if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) {
58 for (i = 0; i < TSC_READ_COUNT; i++) {
59 c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
60 rand_pool_add(pool, &c, 1, 4);
63 return rand_pool_entropy_available(pool);
67 #ifdef OPENSSL_RAND_SEED_RDCPU
68 size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf, size_t len);
69 size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf, size_t len);
71 extern unsigned int OPENSSL_ia32cap_P[];
74 * Acquire entropy using Intel-specific cpu instructions
76 * Uses the RDSEED instruction if available, otherwise uses
77 * RDRAND if available.
79 * For the differences between RDSEED and RDRAND, and why RDSEED
80 * is the preferred choice, see https://goo.gl/oK3KcN
82 * Returns the total entropy count, if it exceeds the requested
83 * entropy count. Otherwise, returns an entropy count of 0.
85 size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool)
88 unsigned char *buffer;
90 bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
91 if (bytes_needed > 0) {
92 buffer = rand_pool_add_begin(pool, bytes_needed);
95 /* Whichever comes first, use RDSEED, RDRAND or nothing */
96 if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) {
97 if (OPENSSL_ia32_rdseed_bytes(buffer, bytes_needed)
99 rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
101 } else if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
102 if (OPENSSL_ia32_rdrand_bytes(buffer, bytes_needed)
104 rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
107 rand_pool_add_end(pool, 0, 0);
112 return rand_pool_entropy_available(pool);
118 * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())
120 * If the DRBG has a parent, then the required amount of entropy input
121 * is fetched using the parent's RAND_DRBG_generate().
123 * Otherwise, the entropy is polled from the system entropy sources
124 * using rand_pool_acquire_entropy().
126 * If a random pool has been added to the DRBG using RAND_add(), then
127 * its entropy will be used up first.
129 size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
130 unsigned char **pout,
131 int entropy, size_t min_len, size_t max_len,
132 int prediction_resistance)
135 size_t entropy_available = 0;
138 if (drbg->parent && drbg->strength > drbg->parent->strength) {
140 * We currently don't support the algorithm from NIST SP 800-90C
141 * 10.1.2 to use a weaker DRBG as source
143 RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY, RAND_R_PARENT_STRENGTH_TOO_WEAK);
147 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, 1 /*entropy_factor*/);
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. (Note: taking the lock will be a no-op
171 * if locking if drbg->parent->lock == NULL.)
173 rand_drbg_lock(drbg->parent);
174 if (RAND_DRBG_generate(drbg->parent,
175 buffer, bytes_needed,
176 prediction_resistance,
177 (unsigned char *)drbg, sizeof(*drbg)) != 0)
178 bytes = bytes_needed;
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 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 OPENSSL_secure_clear_free(out, outlen);
223 * Implements the get_nonce() callback (see RAND_DRBG_set_callbacks())
226 size_t rand_drbg_get_nonce(RAND_DRBG *drbg,
227 unsigned char **pout,
228 int entropy, size_t min_len, size_t max_len)
238 pool = rand_pool_new(0, min_len, max_len);
242 if (rand_pool_add_nonce_data(pool) == 0)
245 data.instance = drbg;
246 CRYPTO_atomic_add(&rand_nonce_count, 1, &data.count, rand_nonce_lock);
248 if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)
251 ret = rand_pool_length(pool);
252 *pout = rand_pool_detach(pool);
255 rand_pool_free(pool);
261 * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())
264 void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,
265 unsigned char *out, size_t outlen)
267 OPENSSL_secure_clear_free(out, outlen);
271 * Generate additional data that can be used for the drbg. The data does
272 * not need to contain entropy, but it's useful if it contains at least
273 * some bits that are unpredictable.
275 * Returns 0 on failure.
277 * On success it allocates a buffer at |*pout| and returns the length of
278 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
280 size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len)
285 pool = rand_pool_new(0, 0, max_len);
289 if (rand_pool_add_additional_data(pool) == 0)
292 ret = rand_pool_length(pool);
293 *pout = rand_pool_detach(pool);
296 rand_pool_free(pool);
301 void rand_drbg_cleanup_additional_data(unsigned char *out, size_t outlen)
303 OPENSSL_secure_clear_free(out, outlen);
311 DEFINE_RUN_ONCE_STATIC(do_rand_init)
313 #ifndef OPENSSL_NO_ENGINE
314 rand_engine_lock = CRYPTO_THREAD_lock_new();
315 if (rand_engine_lock == NULL)
319 rand_meth_lock = CRYPTO_THREAD_lock_new();
320 if (rand_meth_lock == NULL)
323 rand_nonce_lock = CRYPTO_THREAD_lock_new();
324 if (rand_nonce_lock == NULL)
327 if (!rand_pool_init())
335 CRYPTO_THREAD_lock_free(rand_meth_lock);
336 rand_meth_lock = NULL;
338 #ifndef OPENSSL_NO_ENGINE
339 CRYPTO_THREAD_lock_free(rand_engine_lock);
340 rand_engine_lock = NULL;
345 void rand_cleanup_int(void)
347 const RAND_METHOD *meth = default_RAND_meth;
349 if (meth != NULL && meth->cleanup != NULL)
352 RAND_set_rand_method(NULL);
353 #ifndef OPENSSL_NO_ENGINE
354 CRYPTO_THREAD_lock_free(rand_engine_lock);
355 rand_engine_lock = NULL;
357 CRYPTO_THREAD_lock_free(rand_meth_lock);
358 rand_meth_lock = NULL;
359 CRYPTO_THREAD_lock_free(rand_nonce_lock);
360 rand_nonce_lock = NULL;
364 * RAND_close_seed_files() ensures that any seed file decriptors are
367 void RAND_keep_random_devices_open(int keep)
369 rand_pool_keep_random_devices_open(keep);
373 * RAND_poll() reseeds the default RNG using random input
375 * The random input is obtained from polling various entropy
376 * sources which depend on the operating system and are
377 * configurable via the --with-rand-seed configure option.
383 RAND_POOL *pool = NULL;
385 const RAND_METHOD *meth = RAND_get_rand_method();
387 if (meth == RAND_OpenSSL()) {
388 /* fill random pool and seed the master DRBG */
389 RAND_DRBG *drbg = RAND_DRBG_get0_master();
394 rand_drbg_lock(drbg);
395 ret = rand_drbg_restart(drbg, NULL, 0, 0);
396 rand_drbg_unlock(drbg);
401 /* fill random pool and seed the current legacy RNG */
402 pool = rand_pool_new(RAND_DRBG_STRENGTH,
403 RAND_DRBG_STRENGTH / 8,
404 DRBG_MINMAX_FACTOR * (RAND_DRBG_STRENGTH / 8));
408 if (rand_pool_acquire_entropy(pool) == 0)
411 if (meth->add == NULL
412 || meth->add(rand_pool_buffer(pool),
413 rand_pool_length(pool),
414 (rand_pool_entropy(pool) / 8.0)) == 0)
421 rand_pool_free(pool);
426 * Allocate memory and initialize a new random pool
429 RAND_POOL *rand_pool_new(int entropy, size_t min_len, size_t max_len)
431 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
434 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
438 pool->min_len = min_len;
439 pool->max_len = max_len;
441 pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
442 if (pool->buffer == NULL) {
443 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
447 pool->requested_entropy = entropy;
457 * Free |pool|, securely erasing its buffer.
459 void rand_pool_free(RAND_POOL *pool)
464 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
469 * Return the |pool|'s buffer to the caller (readonly).
471 const unsigned char *rand_pool_buffer(RAND_POOL *pool)
477 * Return the |pool|'s entropy to the caller.
479 size_t rand_pool_entropy(RAND_POOL *pool)
481 return pool->entropy;
485 * Return the |pool|'s buffer length to the caller.
487 size_t rand_pool_length(RAND_POOL *pool)
493 * Detach the |pool| buffer and return it to the caller.
494 * It's the responsibility of the caller to free the buffer
495 * using OPENSSL_secure_clear_free().
497 unsigned char *rand_pool_detach(RAND_POOL *pool)
499 unsigned char *ret = pool->buffer;
506 * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one
507 * need to obtain at least |bits| bits of entropy?
509 #define ENTROPY_TO_BYTES(bits, entropy_factor) \
510 (((bits) * (entropy_factor) + 7) / 8)
514 * Checks whether the |pool|'s entropy is available to the caller.
515 * This is the case when entropy count and buffer length are high enough.
518 * |entropy| if the entropy count and buffer size is large enough
521 size_t rand_pool_entropy_available(RAND_POOL *pool)
523 if (pool->entropy < pool->requested_entropy)
526 if (pool->len < pool->min_len)
529 return pool->entropy;
533 * Returns the (remaining) amount of entropy needed to fill
537 size_t rand_pool_entropy_needed(RAND_POOL *pool)
539 if (pool->entropy < pool->requested_entropy)
540 return pool->requested_entropy - pool->entropy;
546 * Returns the number of bytes needed to fill the pool, assuming
547 * the input has 1 / |entropy_factor| entropy bits per data bit.
548 * In case of an error, 0 is returned.
551 size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)
554 size_t entropy_needed = rand_pool_entropy_needed(pool);
556 if (entropy_factor < 1) {
557 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
561 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor);
563 if (bytes_needed > pool->max_len - pool->len) {
564 /* not enough space left */
565 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
569 if (pool->len < pool->min_len &&
570 bytes_needed < pool->min_len - pool->len)
571 /* to meet the min_len requirement */
572 bytes_needed = pool->min_len - pool->len;
577 /* Returns the remaining number of bytes available */
578 size_t rand_pool_bytes_remaining(RAND_POOL *pool)
580 return pool->max_len - pool->len;
584 * Add random bytes to the random pool.
586 * It is expected that the |buffer| contains |len| bytes of
587 * random input which contains at least |entropy| bits of
590 * Returns 1 if the added amount is adequate, otherwise 0
592 int rand_pool_add(RAND_POOL *pool,
593 const unsigned char *buffer, size_t len, size_t entropy)
595 if (len > pool->max_len - pool->len) {
596 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
601 memcpy(pool->buffer + pool->len, buffer, len);
603 pool->entropy += entropy;
610 * Start to add random bytes to the random pool in-place.
612 * Reserves the next |len| bytes for adding random bytes in-place
613 * and returns a pointer to the buffer.
614 * The caller is allowed to copy up to |len| bytes into the buffer.
615 * If |len| == 0 this is considered a no-op and a NULL pointer
616 * is returned without producing an error message.
618 * After updating the buffer, rand_pool_add_end() needs to be called
619 * to finish the udpate operation (see next comment).
621 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
626 if (len > pool->max_len - pool->len) {
627 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
631 return pool->buffer + pool->len;
635 * Finish to add random bytes to the random pool in-place.
637 * Finishes an in-place update of the random pool started by
638 * rand_pool_add_begin() (see previous comment).
639 * It is expected that |len| bytes of random input have been added
640 * to the buffer which contain at least |entropy| bits of randomness.
641 * It is allowed to add less bytes than originally reserved.
643 int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
645 if (len > pool->max_len - pool->len) {
646 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
652 pool->entropy += entropy;
658 int RAND_set_rand_method(const RAND_METHOD *meth)
660 if (!RUN_ONCE(&rand_init, do_rand_init))
663 CRYPTO_THREAD_write_lock(rand_meth_lock);
664 #ifndef OPENSSL_NO_ENGINE
665 ENGINE_finish(funct_ref);
668 default_RAND_meth = meth;
669 CRYPTO_THREAD_unlock(rand_meth_lock);
673 const RAND_METHOD *RAND_get_rand_method(void)
675 const RAND_METHOD *tmp_meth = NULL;
677 if (!RUN_ONCE(&rand_init, do_rand_init))
680 CRYPTO_THREAD_write_lock(rand_meth_lock);
681 if (default_RAND_meth == NULL) {
682 #ifndef OPENSSL_NO_ENGINE
685 /* If we have an engine that can do RAND, use it. */
686 if ((e = ENGINE_get_default_RAND()) != NULL
687 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
689 default_RAND_meth = tmp_meth;
692 default_RAND_meth = &rand_meth;
695 default_RAND_meth = &rand_meth;
698 tmp_meth = default_RAND_meth;
699 CRYPTO_THREAD_unlock(rand_meth_lock);
703 #ifndef OPENSSL_NO_ENGINE
704 int RAND_set_rand_engine(ENGINE *engine)
706 const RAND_METHOD *tmp_meth = NULL;
708 if (!RUN_ONCE(&rand_init, do_rand_init))
711 if (engine != NULL) {
712 if (!ENGINE_init(engine))
714 tmp_meth = ENGINE_get_RAND(engine);
715 if (tmp_meth == NULL) {
716 ENGINE_finish(engine);
720 CRYPTO_THREAD_write_lock(rand_engine_lock);
721 /* This function releases any prior ENGINE so call it first */
722 RAND_set_rand_method(tmp_meth);
724 CRYPTO_THREAD_unlock(rand_engine_lock);
729 void RAND_seed(const void *buf, int num)
731 const RAND_METHOD *meth = RAND_get_rand_method();
733 if (meth->seed != NULL)
734 meth->seed(buf, num);
737 void RAND_add(const void *buf, int num, double randomness)
739 const RAND_METHOD *meth = RAND_get_rand_method();
741 if (meth->add != NULL)
742 meth->add(buf, num, randomness);
746 * This function is not part of RAND_METHOD, so if we're not using
747 * the default method, then just call RAND_bytes(). Otherwise make
748 * sure we're instantiated and use the private DRBG.
750 int RAND_priv_bytes(unsigned char *buf, int num)
752 const RAND_METHOD *meth = RAND_get_rand_method();
756 if (meth != RAND_OpenSSL())
757 return RAND_bytes(buf, num);
759 drbg = RAND_DRBG_get0_private();
763 ret = RAND_DRBG_bytes(drbg, buf, num);
767 int RAND_bytes(unsigned char *buf, int num)
769 const RAND_METHOD *meth = RAND_get_rand_method();
771 if (meth->bytes != NULL)
772 return meth->bytes(buf, num);
773 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
777 #if OPENSSL_API_COMPAT < 0x10100000L
778 int RAND_pseudo_bytes(unsigned char *buf, int num)
780 const RAND_METHOD *meth = RAND_get_rand_method();
782 if (meth->pseudorand != NULL)
783 return meth->pseudorand(buf, num);
788 int RAND_status(void)
790 const RAND_METHOD *meth = RAND_get_rand_method();
792 if (meth->status != NULL)
793 return meth->status();