2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (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_inited = 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 != NULL && 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);
158 if (drbg->parent != NULL) {
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 memset(&data, 0, sizeof(data));
241 pool = rand_pool_new(0, min_len, max_len);
245 if (rand_pool_add_nonce_data(pool) == 0)
248 data.instance = drbg;
249 CRYPTO_atomic_add(&rand_nonce_count, 1, &data.count, rand_nonce_lock);
251 if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)
254 ret = rand_pool_length(pool);
255 *pout = rand_pool_detach(pool);
258 rand_pool_free(pool);
264 * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())
267 void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,
268 unsigned char *out, size_t outlen)
270 OPENSSL_secure_clear_free(out, outlen);
274 * Generate additional data that can be used for the drbg. The data does
275 * not need to contain entropy, but it's useful if it contains at least
276 * some bits that are unpredictable.
278 * Returns 0 on failure.
280 * On success it allocates a buffer at |*pout| and returns the length of
281 * the data. The buffer should get freed using OPENSSL_secure_clear_free().
283 size_t rand_drbg_get_additional_data(RAND_POOL *pool, unsigned char **pout)
287 if (rand_pool_add_additional_data(pool) == 0)
290 ret = rand_pool_length(pool);
291 *pout = rand_pool_detach(pool);
297 void rand_drbg_cleanup_additional_data(RAND_POOL *pool, unsigned char *out)
299 rand_pool_reattach(pool, out);
307 DEFINE_RUN_ONCE_STATIC(do_rand_init)
309 #ifndef OPENSSL_NO_ENGINE
310 rand_engine_lock = CRYPTO_THREAD_lock_new();
311 if (rand_engine_lock == NULL)
315 rand_meth_lock = CRYPTO_THREAD_lock_new();
316 if (rand_meth_lock == NULL)
319 rand_nonce_lock = CRYPTO_THREAD_lock_new();
320 if (rand_nonce_lock == NULL)
323 if (!rand_pool_init())
330 CRYPTO_THREAD_lock_free(rand_nonce_lock);
331 rand_nonce_lock = NULL;
333 CRYPTO_THREAD_lock_free(rand_meth_lock);
334 rand_meth_lock = NULL;
336 #ifndef OPENSSL_NO_ENGINE
337 CRYPTO_THREAD_lock_free(rand_engine_lock);
338 rand_engine_lock = NULL;
343 void rand_cleanup_int(void)
345 const RAND_METHOD *meth = default_RAND_meth;
350 if (meth != NULL && meth->cleanup != NULL)
352 RAND_set_rand_method(NULL);
354 #ifndef OPENSSL_NO_ENGINE
355 CRYPTO_THREAD_lock_free(rand_engine_lock);
356 rand_engine_lock = NULL;
358 CRYPTO_THREAD_lock_free(rand_meth_lock);
359 rand_meth_lock = NULL;
360 CRYPTO_THREAD_lock_free(rand_nonce_lock);
361 rand_nonce_lock = NULL;
366 * RAND_close_seed_files() ensures that any seed file decriptors are
369 void RAND_keep_random_devices_open(int keep)
371 if (RUN_ONCE(&rand_init, do_rand_init))
372 rand_pool_keep_random_devices_open(keep);
376 * RAND_poll() reseeds the default RNG using random input
378 * The random input is obtained from polling various entropy
379 * sources which depend on the operating system and are
380 * configurable via the --with-rand-seed configure option.
386 RAND_POOL *pool = NULL;
388 const RAND_METHOD *meth = RAND_get_rand_method();
390 if (meth == RAND_OpenSSL()) {
391 /* fill random pool and seed the master DRBG */
392 RAND_DRBG *drbg = RAND_DRBG_get0_master();
397 rand_drbg_lock(drbg);
398 ret = rand_drbg_restart(drbg, NULL, 0, 0);
399 rand_drbg_unlock(drbg);
404 /* fill random pool and seed the current legacy RNG */
405 pool = rand_pool_new(RAND_DRBG_STRENGTH,
406 (RAND_DRBG_STRENGTH + 7) / 8,
407 RAND_POOL_MAX_LENGTH);
411 if (rand_pool_acquire_entropy(pool) == 0)
414 if (meth->add == NULL
415 || meth->add(rand_pool_buffer(pool),
416 rand_pool_length(pool),
417 (rand_pool_entropy(pool) / 8.0)) == 0)
424 rand_pool_free(pool);
429 * Allocate memory and initialize a new random pool
432 RAND_POOL *rand_pool_new(int entropy_requested, size_t min_len, size_t max_len)
434 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
437 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
441 pool->min_len = min_len;
442 pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ?
443 RAND_POOL_MAX_LENGTH : max_len;
445 pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
446 if (pool->buffer == NULL) {
447 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
451 pool->entropy_requested = entropy_requested;
461 * Attach new random pool to the given buffer
463 * This function is intended to be used only for feeding random data
464 * provided by RAND_add() and RAND_seed() into the <master> DRBG.
466 RAND_POOL *rand_pool_attach(const unsigned char *buffer, size_t len,
469 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
472 RANDerr(RAND_F_RAND_POOL_ATTACH, ERR_R_MALLOC_FAILURE);
477 * The const needs to be cast away, but attached buffers will not be
478 * modified (in contrary to allocated buffers which are zeroed and
481 pool->buffer = (unsigned char *) buffer;
486 pool->min_len = pool->max_len = pool->len;
487 pool->entropy = entropy;
493 * Free |pool|, securely erasing its buffer.
495 void rand_pool_free(RAND_POOL *pool)
501 * Although it would be advisable from a cryptographical viewpoint,
502 * we are not allowed to clear attached buffers, since they are passed
503 * to rand_pool_attach() as `const unsigned char*`.
504 * (see corresponding comment in rand_pool_attach()).
507 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
512 * Return the |pool|'s buffer to the caller (readonly).
514 const unsigned char *rand_pool_buffer(RAND_POOL *pool)
520 * Return the |pool|'s entropy to the caller.
522 size_t rand_pool_entropy(RAND_POOL *pool)
524 return pool->entropy;
528 * Return the |pool|'s buffer length to the caller.
530 size_t rand_pool_length(RAND_POOL *pool)
536 * Detach the |pool| buffer and return it to the caller.
537 * It's the responsibility of the caller to free the buffer
538 * using OPENSSL_secure_clear_free() or to re-attach it
539 * again to the pool using rand_pool_reattach().
541 unsigned char *rand_pool_detach(RAND_POOL *pool)
543 unsigned char *ret = pool->buffer;
550 * Re-attach the |pool| buffer. It is only allowed to pass
551 * the |buffer| which was previously detached from the same pool.
553 void rand_pool_reattach(RAND_POOL *pool, unsigned char *buffer)
555 pool->buffer = buffer;
556 OPENSSL_cleanse(pool->buffer, pool->len);
561 * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one
562 * need to obtain at least |bits| bits of entropy?
564 #define ENTROPY_TO_BYTES(bits, entropy_factor) \
565 (((bits) * (entropy_factor) + 7) / 8)
569 * Checks whether the |pool|'s entropy is available to the caller.
570 * This is the case when entropy count and buffer length are high enough.
573 * |entropy| if the entropy count and buffer size is large enough
576 size_t rand_pool_entropy_available(RAND_POOL *pool)
578 if (pool->entropy < pool->entropy_requested)
581 if (pool->len < pool->min_len)
584 return pool->entropy;
588 * Returns the (remaining) amount of entropy needed to fill
592 size_t rand_pool_entropy_needed(RAND_POOL *pool)
594 if (pool->entropy < pool->entropy_requested)
595 return pool->entropy_requested - pool->entropy;
601 * Returns the number of bytes needed to fill the pool, assuming
602 * the input has 1 / |entropy_factor| entropy bits per data bit.
603 * In case of an error, 0 is returned.
606 size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)
609 size_t entropy_needed = rand_pool_entropy_needed(pool);
611 if (entropy_factor < 1) {
612 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
616 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor);
618 if (bytes_needed > pool->max_len - pool->len) {
619 /* not enough space left */
620 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
624 if (pool->len < pool->min_len &&
625 bytes_needed < pool->min_len - pool->len)
626 /* to meet the min_len requirement */
627 bytes_needed = pool->min_len - pool->len;
632 /* Returns the remaining number of bytes available */
633 size_t rand_pool_bytes_remaining(RAND_POOL *pool)
635 return pool->max_len - pool->len;
639 * Add random bytes to the random pool.
641 * It is expected that the |buffer| contains |len| bytes of
642 * random input which contains at least |entropy| bits of
645 * Returns 1 if the added amount is adequate, otherwise 0
647 int rand_pool_add(RAND_POOL *pool,
648 const unsigned char *buffer, size_t len, size_t entropy)
650 if (len > pool->max_len - pool->len) {
651 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
655 if (pool->buffer == NULL) {
656 RANDerr(RAND_F_RAND_POOL_ADD, ERR_R_INTERNAL_ERROR);
661 memcpy(pool->buffer + pool->len, buffer, len);
663 pool->entropy += entropy;
670 * Start to add random bytes to the random pool in-place.
672 * Reserves the next |len| bytes for adding random bytes in-place
673 * and returns a pointer to the buffer.
674 * The caller is allowed to copy up to |len| bytes into the buffer.
675 * If |len| == 0 this is considered a no-op and a NULL pointer
676 * is returned without producing an error message.
678 * After updating the buffer, rand_pool_add_end() needs to be called
679 * to finish the udpate operation (see next comment).
681 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
686 if (len > pool->max_len - pool->len) {
687 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
691 if (pool->buffer == NULL) {
692 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, ERR_R_INTERNAL_ERROR);
696 return pool->buffer + pool->len;
700 * Finish to add random bytes to the random pool in-place.
702 * Finishes an in-place update of the random pool started by
703 * rand_pool_add_begin() (see previous comment).
704 * It is expected that |len| bytes of random input have been added
705 * to the buffer which contain at least |entropy| bits of randomness.
706 * It is allowed to add less bytes than originally reserved.
708 int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
710 if (len > pool->max_len - pool->len) {
711 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
717 pool->entropy += entropy;
723 int RAND_set_rand_method(const RAND_METHOD *meth)
725 if (!RUN_ONCE(&rand_init, do_rand_init))
728 CRYPTO_THREAD_write_lock(rand_meth_lock);
729 #ifndef OPENSSL_NO_ENGINE
730 ENGINE_finish(funct_ref);
733 default_RAND_meth = meth;
734 CRYPTO_THREAD_unlock(rand_meth_lock);
738 const RAND_METHOD *RAND_get_rand_method(void)
740 const RAND_METHOD *tmp_meth = NULL;
742 if (!RUN_ONCE(&rand_init, do_rand_init))
745 CRYPTO_THREAD_write_lock(rand_meth_lock);
746 if (default_RAND_meth == NULL) {
747 #ifndef OPENSSL_NO_ENGINE
750 /* If we have an engine that can do RAND, use it. */
751 if ((e = ENGINE_get_default_RAND()) != NULL
752 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
754 default_RAND_meth = tmp_meth;
757 default_RAND_meth = &rand_meth;
760 default_RAND_meth = &rand_meth;
763 tmp_meth = default_RAND_meth;
764 CRYPTO_THREAD_unlock(rand_meth_lock);
768 #ifndef OPENSSL_NO_ENGINE
769 int RAND_set_rand_engine(ENGINE *engine)
771 const RAND_METHOD *tmp_meth = NULL;
773 if (!RUN_ONCE(&rand_init, do_rand_init))
776 if (engine != NULL) {
777 if (!ENGINE_init(engine))
779 tmp_meth = ENGINE_get_RAND(engine);
780 if (tmp_meth == NULL) {
781 ENGINE_finish(engine);
785 CRYPTO_THREAD_write_lock(rand_engine_lock);
786 /* This function releases any prior ENGINE so call it first */
787 RAND_set_rand_method(tmp_meth);
789 CRYPTO_THREAD_unlock(rand_engine_lock);
794 void RAND_seed(const void *buf, int num)
796 const RAND_METHOD *meth = RAND_get_rand_method();
798 if (meth->seed != NULL)
799 meth->seed(buf, num);
802 void RAND_add(const void *buf, int num, double randomness)
804 const RAND_METHOD *meth = RAND_get_rand_method();
806 if (meth->add != NULL)
807 meth->add(buf, num, randomness);
811 * This function is not part of RAND_METHOD, so if we're not using
812 * the default method, then just call RAND_bytes(). Otherwise make
813 * sure we're instantiated and use the private DRBG.
815 int RAND_priv_bytes(unsigned char *buf, int num)
817 const RAND_METHOD *meth = RAND_get_rand_method();
821 if (meth != RAND_OpenSSL())
822 return RAND_bytes(buf, num);
824 drbg = RAND_DRBG_get0_private();
828 ret = RAND_DRBG_bytes(drbg, buf, num);
832 int RAND_bytes(unsigned char *buf, int num)
834 const RAND_METHOD *meth = RAND_get_rand_method();
836 if (meth->bytes != NULL)
837 return meth->bytes(buf, num);
838 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
842 #if !OPENSSL_API_1_1_0
843 int RAND_pseudo_bytes(unsigned char *buf, int num)
845 const RAND_METHOD *meth = RAND_get_rand_method();
847 if (meth->pseudorand != NULL)
848 return meth->pseudorand(buf, num);
853 int RAND_status(void)
855 const RAND_METHOD *meth = RAND_get_rand_method();
857 if (meth->status != NULL)
858 return meth->status();