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->pool != NULL) {
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 /* we need to reset drbg->pool in the error case */
208 if (ret == 0 && drbg->pool != NULL)
211 rand_pool_free(pool);
216 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
219 void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
220 unsigned char *out, size_t outlen)
222 if (drbg->pool == NULL)
223 OPENSSL_secure_clear_free(out, outlen);
230 * Implements the get_nonce() callback (see RAND_DRBG_set_callbacks())
233 size_t rand_drbg_get_nonce(RAND_DRBG *drbg,
234 unsigned char **pout,
235 int entropy, size_t min_len, size_t max_len)
245 pool = rand_pool_new(0, min_len, max_len);
249 if (rand_pool_add_nonce_data(pool) == 0)
252 data.instance = drbg;
253 CRYPTO_atomic_add(&rand_nonce_count, 1, &data.count, rand_nonce_lock);
255 if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)
258 ret = rand_pool_length(pool);
259 *pout = rand_pool_detach(pool);
262 rand_pool_free(pool);
268 * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())
271 void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,
272 unsigned char *out, size_t outlen)
274 OPENSSL_secure_clear_free(out, outlen);
278 * Generate additional data that can be used for the drbg. The data does
279 * not need to contain entropy, but it's useful if it contains at least
280 * some bits that are unpredictable.
282 * Returns 0 on failure.
284 * On success it allocates a buffer at |*pout| and returns the length of
285 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
287 size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len)
292 pool = rand_pool_new(0, 0, max_len);
296 if (rand_pool_add_additional_data(pool) == 0)
299 ret = rand_pool_length(pool);
300 *pout = rand_pool_detach(pool);
303 rand_pool_free(pool);
308 void rand_drbg_cleanup_additional_data(unsigned char *out, size_t outlen)
310 OPENSSL_secure_clear_free(out, outlen);
318 DEFINE_RUN_ONCE_STATIC(do_rand_init)
320 #ifndef OPENSSL_NO_ENGINE
321 rand_engine_lock = CRYPTO_THREAD_lock_new();
322 if (rand_engine_lock == NULL)
326 rand_meth_lock = CRYPTO_THREAD_lock_new();
327 if (rand_meth_lock == NULL)
330 rand_nonce_lock = CRYPTO_THREAD_lock_new();
331 if (rand_nonce_lock == NULL)
334 if (!rand_cleaning_up && !rand_pool_init())
342 CRYPTO_THREAD_lock_free(rand_meth_lock);
343 rand_meth_lock = NULL;
345 #ifndef OPENSSL_NO_ENGINE
346 CRYPTO_THREAD_lock_free(rand_engine_lock);
347 rand_engine_lock = NULL;
352 void rand_cleanup_int(void)
354 const RAND_METHOD *meth = default_RAND_meth;
356 rand_cleaning_up = 1;
358 if (meth != NULL && meth->cleanup != NULL)
360 RAND_set_rand_method(NULL);
362 #ifndef OPENSSL_NO_ENGINE
363 CRYPTO_THREAD_lock_free(rand_engine_lock);
364 rand_engine_lock = NULL;
366 CRYPTO_THREAD_lock_free(rand_meth_lock);
367 rand_meth_lock = NULL;
368 CRYPTO_THREAD_lock_free(rand_nonce_lock);
369 rand_nonce_lock = NULL;
373 * RAND_close_seed_files() ensures that any seed file decriptors are
376 void RAND_keep_random_devices_open(int keep)
378 rand_pool_keep_random_devices_open(keep);
382 * RAND_poll() reseeds the default RNG using random input
384 * The random input is obtained from polling various entropy
385 * sources which depend on the operating system and are
386 * configurable via the --with-rand-seed configure option.
392 RAND_POOL *pool = NULL;
394 const RAND_METHOD *meth = RAND_get_rand_method();
396 if (meth == RAND_OpenSSL()) {
397 /* fill random pool and seed the master DRBG */
398 RAND_DRBG *drbg = RAND_DRBG_get0_master();
403 rand_drbg_lock(drbg);
404 ret = rand_drbg_restart(drbg, NULL, 0, 0);
405 rand_drbg_unlock(drbg);
410 /* fill random pool and seed the current legacy RNG */
411 pool = rand_pool_new(RAND_DRBG_STRENGTH,
412 RAND_DRBG_STRENGTH / 8,
413 RAND_POOL_MAX_LENGTH);
417 if (rand_pool_acquire_entropy(pool) == 0)
420 if (meth->add == NULL
421 || meth->add(rand_pool_buffer(pool),
422 rand_pool_length(pool),
423 (rand_pool_entropy(pool) / 8.0)) == 0)
430 rand_pool_free(pool);
435 * Allocate memory and initialize a new random pool
438 RAND_POOL *rand_pool_new(int entropy_requested, size_t min_len, size_t max_len)
440 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
443 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
447 pool->min_len = min_len;
448 pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ?
449 RAND_POOL_MAX_LENGTH : max_len;
451 pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
452 if (pool->buffer == NULL) {
453 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
457 pool->entropy_requested = entropy_requested;
467 * Attach new random pool to the given buffer
469 * This function is intended to be used only for feeding random data
470 * provided by RAND_add() and RAND_seed() into the <master> DRBG.
472 RAND_POOL *rand_pool_attach(const unsigned char *buffer, size_t len,
475 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
478 RANDerr(RAND_F_RAND_POOL_ATTACH, ERR_R_MALLOC_FAILURE);
483 * The const needs to be cast away, but attached buffers will not be
484 * modified (in contrary to allocated buffers which are zeroed and
487 pool->buffer = (unsigned char *) buffer;
492 pool->min_len = pool->max_len = pool->len;
493 pool->entropy = entropy;
499 * Free |pool|, securely erasing its buffer.
501 void rand_pool_free(RAND_POOL *pool)
507 * Although it would be advisable from a cryptographical viewpoint,
508 * we are not allowed to clear attached buffers, since they are passed
509 * to rand_pool_attach() as `const unsigned char*`.
510 * (see corresponding comment in rand_pool_attach()).
513 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
518 * Return the |pool|'s buffer to the caller (readonly).
520 const unsigned char *rand_pool_buffer(RAND_POOL *pool)
526 * Return the |pool|'s entropy to the caller.
528 size_t rand_pool_entropy(RAND_POOL *pool)
530 return pool->entropy;
534 * Return the |pool|'s buffer length to the caller.
536 size_t rand_pool_length(RAND_POOL *pool)
542 * Detach the |pool| buffer and return it to the caller.
543 * It's the responsibility of the caller to free the buffer
544 * using OPENSSL_secure_clear_free().
546 unsigned char *rand_pool_detach(RAND_POOL *pool)
548 unsigned char *ret = pool->buffer;
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);
650 memcpy(pool->buffer + pool->len, buffer, len);
652 pool->entropy += entropy;
659 * Start to add random bytes to the random pool in-place.
661 * Reserves the next |len| bytes for adding random bytes in-place
662 * and returns a pointer to the buffer.
663 * The caller is allowed to copy up to |len| bytes into the buffer.
664 * If |len| == 0 this is considered a no-op and a NULL pointer
665 * is returned without producing an error message.
667 * After updating the buffer, rand_pool_add_end() needs to be called
668 * to finish the udpate operation (see next comment).
670 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
675 if (len > pool->max_len - pool->len) {
676 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
680 return pool->buffer + pool->len;
684 * Finish to add random bytes to the random pool in-place.
686 * Finishes an in-place update of the random pool started by
687 * rand_pool_add_begin() (see previous comment).
688 * It is expected that |len| bytes of random input have been added
689 * to the buffer which contain at least |entropy| bits of randomness.
690 * It is allowed to add less bytes than originally reserved.
692 int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
694 if (len > pool->max_len - pool->len) {
695 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
701 pool->entropy += entropy;
707 int RAND_set_rand_method(const RAND_METHOD *meth)
709 if (!RUN_ONCE(&rand_init, do_rand_init))
712 CRYPTO_THREAD_write_lock(rand_meth_lock);
713 #ifndef OPENSSL_NO_ENGINE
714 ENGINE_finish(funct_ref);
717 default_RAND_meth = meth;
718 CRYPTO_THREAD_unlock(rand_meth_lock);
722 const RAND_METHOD *RAND_get_rand_method(void)
724 const RAND_METHOD *tmp_meth = NULL;
726 if (!RUN_ONCE(&rand_init, do_rand_init))
729 CRYPTO_THREAD_write_lock(rand_meth_lock);
730 if (default_RAND_meth == NULL) {
731 #ifndef OPENSSL_NO_ENGINE
734 /* If we have an engine that can do RAND, use it. */
735 if ((e = ENGINE_get_default_RAND()) != NULL
736 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
738 default_RAND_meth = tmp_meth;
741 default_RAND_meth = &rand_meth;
744 default_RAND_meth = &rand_meth;
747 tmp_meth = default_RAND_meth;
748 CRYPTO_THREAD_unlock(rand_meth_lock);
752 #ifndef OPENSSL_NO_ENGINE
753 int RAND_set_rand_engine(ENGINE *engine)
755 const RAND_METHOD *tmp_meth = NULL;
757 if (!RUN_ONCE(&rand_init, do_rand_init))
760 if (engine != NULL) {
761 if (!ENGINE_init(engine))
763 tmp_meth = ENGINE_get_RAND(engine);
764 if (tmp_meth == NULL) {
765 ENGINE_finish(engine);
769 CRYPTO_THREAD_write_lock(rand_engine_lock);
770 /* This function releases any prior ENGINE so call it first */
771 RAND_set_rand_method(tmp_meth);
773 CRYPTO_THREAD_unlock(rand_engine_lock);
778 void RAND_seed(const void *buf, int num)
780 const RAND_METHOD *meth = RAND_get_rand_method();
782 if (meth->seed != NULL)
783 meth->seed(buf, num);
786 void RAND_add(const void *buf, int num, double randomness)
788 const RAND_METHOD *meth = RAND_get_rand_method();
790 if (meth->add != NULL)
791 meth->add(buf, num, randomness);
795 * This function is not part of RAND_METHOD, so if we're not using
796 * the default method, then just call RAND_bytes(). Otherwise make
797 * sure we're instantiated and use the private DRBG.
799 int RAND_priv_bytes(unsigned char *buf, int num)
801 const RAND_METHOD *meth = RAND_get_rand_method();
805 if (meth != RAND_OpenSSL())
806 return RAND_bytes(buf, num);
808 drbg = RAND_DRBG_get0_private();
812 ret = RAND_DRBG_bytes(drbg, buf, num);
816 int RAND_bytes(unsigned char *buf, int num)
818 const RAND_METHOD *meth = RAND_get_rand_method();
820 if (meth->bytes != NULL)
821 return meth->bytes(buf, num);
822 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
826 #if OPENSSL_API_COMPAT < 0x10100000L
827 int RAND_pseudo_bytes(unsigned char *buf, int num)
829 const RAND_METHOD *meth = RAND_get_rand_method();
831 if (meth->pseudorand != NULL)
832 return meth->pseudorand(buf, num);
837 int RAND_status(void)
839 const RAND_METHOD *meth = RAND_get_rand_method();
841 if (meth->status != NULL)
842 return meth->status();