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, 8 /*entropy_per_byte*/);
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, 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. (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)
315 #ifndef OPENSSL_NO_ENGINE
316 rand_engine_lock = CRYPTO_THREAD_lock_new();
317 ret &= rand_engine_lock != NULL;
319 rand_meth_lock = CRYPTO_THREAD_lock_new();
320 ret &= rand_meth_lock != NULL;
322 rand_nonce_lock = CRYPTO_THREAD_lock_new();
323 ret &= rand_meth_lock != NULL;
328 void rand_cleanup_int(void)
330 const RAND_METHOD *meth = default_RAND_meth;
332 if (meth != NULL && meth->cleanup != NULL)
334 RAND_set_rand_method(NULL);
335 #ifndef OPENSSL_NO_ENGINE
336 CRYPTO_THREAD_lock_free(rand_engine_lock);
338 CRYPTO_THREAD_lock_free(rand_meth_lock);
339 CRYPTO_THREAD_lock_free(rand_nonce_lock);
343 * RAND_poll() reseeds the default RNG using random input
345 * The random input is obtained from polling various entropy
346 * sources which depend on the operating system and are
347 * configurable via the --with-rand-seed configure option.
353 RAND_POOL *pool = NULL;
355 const RAND_METHOD *meth = RAND_get_rand_method();
357 if (meth == RAND_OpenSSL()) {
358 /* fill random pool and seed the master DRBG */
359 RAND_DRBG *drbg = RAND_DRBG_get0_master();
364 rand_drbg_lock(drbg);
365 ret = rand_drbg_restart(drbg, NULL, 0, 0);
366 rand_drbg_unlock(drbg);
371 /* fill random pool and seed the current legacy RNG */
372 pool = rand_pool_new(RAND_DRBG_STRENGTH,
373 RAND_DRBG_STRENGTH / 8,
374 DRBG_MINMAX_FACTOR * (RAND_DRBG_STRENGTH / 8));
378 if (rand_pool_acquire_entropy(pool) == 0)
381 if (meth->add == NULL
382 || meth->add(rand_pool_buffer(pool),
383 rand_pool_length(pool),
384 (rand_pool_entropy(pool) / 8.0)) == 0)
391 rand_pool_free(pool);
396 * Allocate memory and initialize a new random pool
399 RAND_POOL *rand_pool_new(int entropy, size_t min_len, size_t max_len)
401 RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
404 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
408 pool->min_len = min_len;
409 pool->max_len = max_len;
411 pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
412 if (pool->buffer == NULL) {
413 RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
417 pool->requested_entropy = entropy;
427 * Free |pool|, securely erasing its buffer.
429 void rand_pool_free(RAND_POOL *pool)
434 OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
439 * Return the |pool|'s buffer to the caller (readonly).
441 const unsigned char *rand_pool_buffer(RAND_POOL *pool)
447 * Return the |pool|'s entropy to the caller.
449 size_t rand_pool_entropy(RAND_POOL *pool)
451 return pool->entropy;
455 * Return the |pool|'s buffer length to the caller.
457 size_t rand_pool_length(RAND_POOL *pool)
463 * Detach the |pool| buffer and return it to the caller.
464 * It's the responsibility of the caller to free the buffer
465 * using OPENSSL_secure_clear_free().
467 unsigned char *rand_pool_detach(RAND_POOL *pool)
469 unsigned char *ret = pool->buffer;
476 * If every byte of the input contains |entropy_per_bytes| bits of entropy,
477 * how many bytes does one need to obtain at least |bits| bits of entropy?
479 #define ENTROPY_TO_BYTES(bits, entropy_per_bytes) \
480 (((bits) + ((entropy_per_bytes) - 1))/(entropy_per_bytes))
484 * Checks whether the |pool|'s entropy is available to the caller.
485 * This is the case when entropy count and buffer length are high enough.
488 * |entropy| if the entropy count and buffer size is large enough
491 size_t rand_pool_entropy_available(RAND_POOL *pool)
493 if (pool->entropy < pool->requested_entropy)
496 if (pool->len < pool->min_len)
499 return pool->entropy;
503 * Returns the (remaining) amount of entropy needed to fill
507 size_t rand_pool_entropy_needed(RAND_POOL *pool)
509 if (pool->entropy < pool->requested_entropy)
510 return pool->requested_entropy - pool->entropy;
516 * Returns the number of bytes needed to fill the pool, assuming
517 * the input has 'entropy_per_byte' entropy bits per byte.
518 * In case of an error, 0 is returned.
521 size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_per_byte)
524 size_t entropy_needed = rand_pool_entropy_needed(pool);
526 if (entropy_per_byte < 1 || entropy_per_byte > 8) {
527 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
531 bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_per_byte);
533 if (bytes_needed > pool->max_len - pool->len) {
534 /* not enough space left */
535 RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
539 if (pool->len < pool->min_len &&
540 bytes_needed < pool->min_len - pool->len)
541 /* to meet the min_len requirement */
542 bytes_needed = pool->min_len - pool->len;
547 /* Returns the remaining number of bytes available */
548 size_t rand_pool_bytes_remaining(RAND_POOL *pool)
550 return pool->max_len - pool->len;
554 * Add random bytes to the random pool.
556 * It is expected that the |buffer| contains |len| bytes of
557 * random input which contains at least |entropy| bits of
560 * Returns 1 if the added amount is adequate, otherwise 0
562 int rand_pool_add(RAND_POOL *pool,
563 const unsigned char *buffer, size_t len, size_t entropy)
565 if (len > pool->max_len - pool->len) {
566 RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
571 memcpy(pool->buffer + pool->len, buffer, len);
573 pool->entropy += entropy;
580 * Start to add random bytes to the random pool in-place.
582 * Reserves the next |len| bytes for adding random bytes in-place
583 * and returns a pointer to the buffer.
584 * The caller is allowed to copy up to |len| bytes into the buffer.
585 * If |len| == 0 this is considered a no-op and a NULL pointer
586 * is returned without producing an error message.
588 * After updating the buffer, rand_pool_add_end() needs to be called
589 * to finish the udpate operation (see next comment).
591 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
596 if (len > pool->max_len - pool->len) {
597 RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
601 return pool->buffer + pool->len;
605 * Finish to add random bytes to the random pool in-place.
607 * Finishes an in-place update of the random pool started by
608 * rand_pool_add_begin() (see previous comment).
609 * It is expected that |len| bytes of random input have been added
610 * to the buffer which contain at least |entropy| bits of randomness.
611 * It is allowed to add less bytes than originally reserved.
613 int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
615 if (len > pool->max_len - pool->len) {
616 RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
622 pool->entropy += entropy;
628 int RAND_set_rand_method(const RAND_METHOD *meth)
630 if (!RUN_ONCE(&rand_init, do_rand_init))
633 CRYPTO_THREAD_write_lock(rand_meth_lock);
634 #ifndef OPENSSL_NO_ENGINE
635 ENGINE_finish(funct_ref);
638 default_RAND_meth = meth;
639 CRYPTO_THREAD_unlock(rand_meth_lock);
643 const RAND_METHOD *RAND_get_rand_method(void)
645 const RAND_METHOD *tmp_meth = NULL;
647 if (!RUN_ONCE(&rand_init, do_rand_init))
650 CRYPTO_THREAD_write_lock(rand_meth_lock);
651 if (default_RAND_meth == NULL) {
652 #ifndef OPENSSL_NO_ENGINE
655 /* If we have an engine that can do RAND, use it. */
656 if ((e = ENGINE_get_default_RAND()) != NULL
657 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
659 default_RAND_meth = tmp_meth;
662 default_RAND_meth = &rand_meth;
665 default_RAND_meth = &rand_meth;
668 tmp_meth = default_RAND_meth;
669 CRYPTO_THREAD_unlock(rand_meth_lock);
673 #ifndef OPENSSL_NO_ENGINE
674 int RAND_set_rand_engine(ENGINE *engine)
676 const RAND_METHOD *tmp_meth = NULL;
678 if (!RUN_ONCE(&rand_init, do_rand_init))
681 if (engine != NULL) {
682 if (!ENGINE_init(engine))
684 tmp_meth = ENGINE_get_RAND(engine);
685 if (tmp_meth == NULL) {
686 ENGINE_finish(engine);
690 CRYPTO_THREAD_write_lock(rand_engine_lock);
691 /* This function releases any prior ENGINE so call it first */
692 RAND_set_rand_method(tmp_meth);
694 CRYPTO_THREAD_unlock(rand_engine_lock);
699 void RAND_seed(const void *buf, int num)
701 const RAND_METHOD *meth = RAND_get_rand_method();
703 if (meth->seed != NULL)
704 meth->seed(buf, num);
707 void RAND_add(const void *buf, int num, double randomness)
709 const RAND_METHOD *meth = RAND_get_rand_method();
711 if (meth->add != NULL)
712 meth->add(buf, num, randomness);
716 * This function is not part of RAND_METHOD, so if we're not using
717 * the default method, then just call RAND_bytes(). Otherwise make
718 * sure we're instantiated and use the private DRBG.
720 int RAND_priv_bytes(unsigned char *buf, int num)
722 const RAND_METHOD *meth = RAND_get_rand_method();
726 if (meth != RAND_OpenSSL())
727 return RAND_bytes(buf, num);
729 drbg = RAND_DRBG_get0_private();
733 ret = RAND_DRBG_bytes(drbg, buf, num);
737 int RAND_bytes(unsigned char *buf, int num)
739 const RAND_METHOD *meth = RAND_get_rand_method();
741 if (meth->bytes != NULL)
742 return meth->bytes(buf, num);
743 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
747 #if OPENSSL_API_COMPAT < 0x10100000L
748 int RAND_pseudo_bytes(unsigned char *buf, int num)
750 const RAND_METHOD *meth = RAND_get_rand_method();
752 if (meth->pseudorand != NULL)
753 return meth->pseudorand(buf, num);
758 int RAND_status(void)
760 const RAND_METHOD *meth = RAND_get_rand_method();
762 if (meth->status != NULL)
763 return meth->status();