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->seed_pool != NULL) {
150 pool = drbg->seed_pool;
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 if (drbg->seed_pool == NULL)
208 rand_pool_free(pool);
213 * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
216 void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
217 unsigned char *out, size_t outlen)
219 if (drbg->seed_pool == NULL)
220 OPENSSL_secure_clear_free(out, outlen);
225 * Implements the get_nonce() callback (see RAND_DRBG_set_callbacks())
228 size_t rand_drbg_get_nonce(RAND_DRBG *drbg,
229 unsigned char **pout,
230 int entropy, size_t min_len, size_t max_len)
240 pool = rand_pool_new(0, min_len, max_len);
244 if (rand_pool_add_nonce_data(pool) == 0)
247 data.instance = drbg;
248 CRYPTO_atomic_add(&rand_nonce_count, 1, &data.count, rand_nonce_lock);
250 if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)
253 ret = rand_pool_length(pool);
254 *pout = rand_pool_detach(pool);
257 rand_pool_free(pool);
263 * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())
266 void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,
267 unsigned char *out, size_t outlen)
269 OPENSSL_secure_clear_free(out, outlen);
273 * Generate additional data that can be used for the drbg. The data does
274 * not need to contain entropy, but it's useful if it contains at least
275 * some bits that are unpredictable.
277 * Returns 0 on failure.
279 * On success it allocates a buffer at |*pout| and returns the length of
280 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
282 size_t rand_drbg_get_additional_data(RAND_POOL *pool, unsigned char **pout)
286 if (rand_pool_add_additional_data(pool) == 0)
289 ret = rand_pool_length(pool);
290 *pout = rand_pool_detach(pool);
296 void rand_drbg_cleanup_additional_data(RAND_POOL *pool, unsigned char *out)
298 rand_pool_reattach(pool, out);
306 DEFINE_RUN_ONCE_STATIC(do_rand_init)
308 #ifndef OPENSSL_NO_ENGINE
309 rand_engine_lock = CRYPTO_THREAD_lock_new();
310 if (rand_engine_lock == NULL)
314 rand_meth_lock = CRYPTO_THREAD_lock_new();
315 if (rand_meth_lock == NULL)
318 rand_nonce_lock = CRYPTO_THREAD_lock_new();
319 if (rand_nonce_lock == NULL)
322 if (!rand_cleaning_up && !rand_pool_init())
330 CRYPTO_THREAD_lock_free(rand_meth_lock);
331 rand_meth_lock = NULL;
333 #ifndef OPENSSL_NO_ENGINE
334 CRYPTO_THREAD_lock_free(rand_engine_lock);
335 rand_engine_lock = NULL;
340 void rand_cleanup_int(void)
342 const RAND_METHOD *meth = default_RAND_meth;
344 rand_cleaning_up = 1;
346 if (meth != NULL && meth->cleanup != NULL)
348 RAND_set_rand_method(NULL);
350 #ifndef OPENSSL_NO_ENGINE
351 CRYPTO_THREAD_lock_free(rand_engine_lock);
352 rand_engine_lock = NULL;
354 CRYPTO_THREAD_lock_free(rand_meth_lock);
355 rand_meth_lock = NULL;
356 CRYPTO_THREAD_lock_free(rand_nonce_lock);
357 rand_nonce_lock = NULL;
361 * RAND_close_seed_files() ensures that any seed file decriptors are
364 void RAND_keep_random_devices_open(int keep)
366 if (RUN_ONCE(&rand_init, do_rand_init))
367 rand_pool_keep_random_devices_open(keep);
371 * RAND_poll() reseeds the default RNG using random input
373 * The random input is obtained from polling various entropy
374 * sources which depend on the operating system and are
375 * configurable via the --with-rand-seed configure option.
381 RAND_POOL *pool = NULL;
383 const RAND_METHOD *meth = RAND_get_rand_method();
385 if (meth == RAND_OpenSSL()) {
386 /* fill random pool and seed the master DRBG */
387 RAND_DRBG *drbg = RAND_DRBG_get0_master();
392 rand_drbg_lock(drbg);
393 ret = rand_drbg_restart(drbg, NULL, 0, 0);
394 rand_drbg_unlock(drbg);
399 /* fill random pool and seed the current legacy RNG */
400 pool = rand_pool_new(RAND_DRBG_STRENGTH,
401 RAND_DRBG_STRENGTH / 8,
402 RAND_POOL_MAX_LENGTH);
406 if (rand_pool_acquire_entropy(pool) == 0)
409 if (meth->add == NULL
410 || meth->add(rand_pool_buffer(pool),
411 rand_pool_length(pool),
412 (rand_pool_entropy(pool) / 8.0)) == 0)
419 rand_pool_free(pool);
424 * Allocate memory and initialize a new random pool
427 RAND_POOL *rand_pool_new(int entropy_requested, size_t min_len, size_t max_len)
429 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
432 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
436 pool->min_len = min_len;
437 pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ?
438 RAND_POOL_MAX_LENGTH : max_len;
440 pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
441 if (pool->buffer == NULL) {
442 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
446 pool->entropy_requested = entropy_requested;
456 * Attach new random pool to the given buffer
458 * This function is intended to be used only for feeding random data
459 * provided by RAND_add() and RAND_seed() into the <master> DRBG.
461 RAND_POOL *rand_pool_attach(const unsigned char *buffer, size_t len,
464 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
467 RANDerr(RAND_F_RAND_POOL_ATTACH, ERR_R_MALLOC_FAILURE);
472 * The const needs to be cast away, but attached buffers will not be
473 * modified (in contrary to allocated buffers which are zeroed and
476 pool->buffer = (unsigned char *) buffer;
481 pool->min_len = pool->max_len = pool->len;
482 pool->entropy = entropy;
488 * Free |pool|, securely erasing its buffer.
490 void rand_pool_free(RAND_POOL *pool)
496 * Although it would be advisable from a cryptographical viewpoint,
497 * we are not allowed to clear attached buffers, since they are passed
498 * to rand_pool_attach() as `const unsigned char*`.
499 * (see corresponding comment in rand_pool_attach()).
502 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
507 * Return the |pool|'s buffer to the caller (readonly).
509 const unsigned char *rand_pool_buffer(RAND_POOL *pool)
515 * Return the |pool|'s entropy to the caller.
517 size_t rand_pool_entropy(RAND_POOL *pool)
519 return pool->entropy;
523 * Return the |pool|'s buffer length to the caller.
525 size_t rand_pool_length(RAND_POOL *pool)
531 * Detach the |pool| buffer and return it to the caller.
532 * It's the responsibility of the caller to free the buffer
533 * using OPENSSL_secure_clear_free() or to re-attach it
534 * again to the pool using rand_pool_reattach().
536 unsigned char *rand_pool_detach(RAND_POOL *pool)
538 unsigned char *ret = pool->buffer;
545 * Re-attach the |pool| buffer. It is only allowed to pass
546 * the |buffer| which was previously detached from the same pool.
548 void rand_pool_reattach(RAND_POOL *pool, unsigned char *buffer)
550 pool->buffer = buffer;
551 OPENSSL_cleanse(pool->buffer, pool->len);
556 * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one
557 * need to obtain at least |bits| bits of entropy?
559 #define ENTROPY_TO_BYTES(bits, entropy_factor) \
560 (((bits) * (entropy_factor) + 7) / 8)
564 * Checks whether the |pool|'s entropy is available to the caller.
565 * This is the case when entropy count and buffer length are high enough.
568 * |entropy| if the entropy count and buffer size is large enough
571 size_t rand_pool_entropy_available(RAND_POOL *pool)
573 if (pool->entropy < pool->entropy_requested)
576 if (pool->len < pool->min_len)
579 return pool->entropy;
583 * Returns the (remaining) amount of entropy needed to fill
587 size_t rand_pool_entropy_needed(RAND_POOL *pool)
589 if (pool->entropy < pool->entropy_requested)
590 return pool->entropy_requested - pool->entropy;
596 * Returns the number of bytes needed to fill the pool, assuming
597 * the input has 1 / |entropy_factor| entropy bits per data bit.
598 * In case of an error, 0 is returned.
601 size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)
604 size_t entropy_needed = rand_pool_entropy_needed(pool);
606 if (entropy_factor < 1) {
607 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
611 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor);
613 if (bytes_needed > pool->max_len - pool->len) {
614 /* not enough space left */
615 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
619 if (pool->len < pool->min_len &&
620 bytes_needed < pool->min_len - pool->len)
621 /* to meet the min_len requirement */
622 bytes_needed = pool->min_len - pool->len;
627 /* Returns the remaining number of bytes available */
628 size_t rand_pool_bytes_remaining(RAND_POOL *pool)
630 return pool->max_len - pool->len;
634 * Add random bytes to the random pool.
636 * It is expected that the |buffer| contains |len| bytes of
637 * random input which contains at least |entropy| bits of
640 * Returns 1 if the added amount is adequate, otherwise 0
642 int rand_pool_add(RAND_POOL *pool,
643 const unsigned char *buffer, size_t len, size_t entropy)
645 if (len > pool->max_len - pool->len) {
646 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
650 if (pool->buffer == NULL) {
651 RANDerr(RAND_F_RAND_POOL_ADD, ERR_R_INTERNAL_ERROR);
656 memcpy(pool->buffer + pool->len, buffer, len);
658 pool->entropy += entropy;
665 * Start to add random bytes to the random pool in-place.
667 * Reserves the next |len| bytes for adding random bytes in-place
668 * and returns a pointer to the buffer.
669 * The caller is allowed to copy up to |len| bytes into the buffer.
670 * If |len| == 0 this is considered a no-op and a NULL pointer
671 * is returned without producing an error message.
673 * After updating the buffer, rand_pool_add_end() needs to be called
674 * to finish the udpate operation (see next comment).
676 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
681 if (len > pool->max_len - pool->len) {
682 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
686 if (pool->buffer == NULL) {
687 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, ERR_R_INTERNAL_ERROR);
691 return pool->buffer + pool->len;
695 * Finish to add random bytes to the random pool in-place.
697 * Finishes an in-place update of the random pool started by
698 * rand_pool_add_begin() (see previous comment).
699 * It is expected that |len| bytes of random input have been added
700 * to the buffer which contain at least |entropy| bits of randomness.
701 * It is allowed to add less bytes than originally reserved.
703 int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
705 if (len > pool->max_len - pool->len) {
706 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
712 pool->entropy += entropy;
718 int RAND_set_rand_method(const RAND_METHOD *meth)
720 if (!RUN_ONCE(&rand_init, do_rand_init))
723 CRYPTO_THREAD_write_lock(rand_meth_lock);
724 #ifndef OPENSSL_NO_ENGINE
725 ENGINE_finish(funct_ref);
728 default_RAND_meth = meth;
729 CRYPTO_THREAD_unlock(rand_meth_lock);
733 const RAND_METHOD *RAND_get_rand_method(void)
735 const RAND_METHOD *tmp_meth = NULL;
737 if (!RUN_ONCE(&rand_init, do_rand_init))
740 CRYPTO_THREAD_write_lock(rand_meth_lock);
741 if (default_RAND_meth == NULL) {
742 #ifndef OPENSSL_NO_ENGINE
745 /* If we have an engine that can do RAND, use it. */
746 if ((e = ENGINE_get_default_RAND()) != NULL
747 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
749 default_RAND_meth = tmp_meth;
752 default_RAND_meth = &rand_meth;
755 default_RAND_meth = &rand_meth;
758 tmp_meth = default_RAND_meth;
759 CRYPTO_THREAD_unlock(rand_meth_lock);
763 #ifndef OPENSSL_NO_ENGINE
764 int RAND_set_rand_engine(ENGINE *engine)
766 const RAND_METHOD *tmp_meth = NULL;
768 if (!RUN_ONCE(&rand_init, do_rand_init))
771 if (engine != NULL) {
772 if (!ENGINE_init(engine))
774 tmp_meth = ENGINE_get_RAND(engine);
775 if (tmp_meth == NULL) {
776 ENGINE_finish(engine);
780 CRYPTO_THREAD_write_lock(rand_engine_lock);
781 /* This function releases any prior ENGINE so call it first */
782 RAND_set_rand_method(tmp_meth);
784 CRYPTO_THREAD_unlock(rand_engine_lock);
789 void RAND_seed(const void *buf, int num)
791 const RAND_METHOD *meth = RAND_get_rand_method();
793 if (meth->seed != NULL)
794 meth->seed(buf, num);
797 void RAND_add(const void *buf, int num, double randomness)
799 const RAND_METHOD *meth = RAND_get_rand_method();
801 if (meth->add != NULL)
802 meth->add(buf, num, randomness);
806 * This function is not part of RAND_METHOD, so if we're not using
807 * the default method, then just call RAND_bytes(). Otherwise make
808 * sure we're instantiated and use the private DRBG.
810 int RAND_priv_bytes(unsigned char *buf, int num)
812 const RAND_METHOD *meth = RAND_get_rand_method();
816 if (meth != RAND_OpenSSL())
817 return RAND_bytes(buf, num);
819 drbg = RAND_DRBG_get0_private();
823 ret = RAND_DRBG_bytes(drbg, buf, num);
827 int RAND_bytes(unsigned char *buf, int num)
829 const RAND_METHOD *meth = RAND_get_rand_method();
831 if (meth->bytes != NULL)
832 return meth->bytes(buf, num);
833 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
837 #if OPENSSL_API_COMPAT < 0x10100000L
838 int RAND_pseudo_bytes(unsigned char *buf, int num)
840 const RAND_METHOD *meth = RAND_get_rand_method();
842 if (meth->pseudorand != NULL)
843 return meth->pseudorand(buf, num);
848 int RAND_status(void)
850 const RAND_METHOD *meth = RAND_get_rand_method();
852 if (meth->status != NULL)
853 return meth->status();