2 * Copyright 2011-2018 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
11 #include <openssl/crypto.h>
12 #include <openssl/err.h>
13 #include <openssl/rand.h>
15 #include "internal/thread_once.h"
16 #include "internal/rand_int.h"
17 #include "internal/cryptlib_int.h"
20 * Support framework for NIST SP 800-90A DRBG
22 * See manual page RAND_DRBG(7) for a general overview.
24 * The OpenSSL model is to have new and free functions, and that new
25 * does all initialization. That is not the NIST model, which has
26 * instantiation and un-instantiate, and re-use within a new/free
27 * lifecycle. (No doubt this comes from the desire to support hardware
28 * DRBG, where allocation of resources on something like an HSM is
29 * a much bigger deal than just re-setting an allocated resource.)
33 * The three shared DRBG instances
35 * There are three shared DRBG instances: <master>, <public>, and <private>.
41 * Not used directly by the application, only for reseeding the two other
42 * DRBGs. It reseeds itself by pulling either randomness from os entropy
43 * sources or by consuming randomness which was added by RAND_add().
45 * The <master> DRBG is a global instance which is accessed concurrently by
46 * all threads. The necessary locking is managed automatically by its child
47 * DRBG instances during reseeding.
49 static RAND_DRBG *master_drbg;
53 * Used by default for generating random bytes using RAND_bytes().
55 * The <public> DRBG is thread-local, i.e., there is one instance per thread.
57 static CRYPTO_THREAD_LOCAL public_drbg;
61 * Used by default for generating private keys using RAND_priv_bytes()
63 * The <private> DRBG is thread-local, i.e., there is one instance per thread.
65 static CRYPTO_THREAD_LOCAL private_drbg;
69 /* NIST SP 800-90A DRBG recommends the use of a personalization string. */
70 static const char ossl_pers_string[] = DRBG_DEFAULT_PERS_STRING;
72 static CRYPTO_ONCE rand_drbg_init = CRYPTO_ONCE_STATIC_INIT;
75 #define RAND_DRBG_TYPE_FLAGS ( \
76 RAND_DRBG_FLAG_MASTER | RAND_DRBG_FLAG_PUBLIC | RAND_DRBG_FLAG_PRIVATE )
78 #define RAND_DRBG_TYPE_MASTER 0
79 #define RAND_DRBG_TYPE_PUBLIC 1
80 #define RAND_DRBG_TYPE_PRIVATE 2
83 static int rand_drbg_type[3] = {
84 RAND_DRBG_TYPE, /* Master */
85 RAND_DRBG_TYPE, /* Public */
86 RAND_DRBG_TYPE /* Private */
88 static unsigned int rand_drbg_flags[3] = {
89 RAND_DRBG_FLAGS | RAND_DRBG_FLAG_MASTER, /* Master */
90 RAND_DRBG_FLAGS | RAND_DRBG_FLAG_PUBLIC, /* Public */
91 RAND_DRBG_FLAGS | RAND_DRBG_FLAG_PRIVATE /* Private */
94 static unsigned int master_reseed_interval = MASTER_RESEED_INTERVAL;
95 static unsigned int slave_reseed_interval = SLAVE_RESEED_INTERVAL;
97 static time_t master_reseed_time_interval = MASTER_RESEED_TIME_INTERVAL;
98 static time_t slave_reseed_time_interval = SLAVE_RESEED_TIME_INTERVAL;
100 /* A logical OR of all used DRBG flag bits (currently there is only one) */
101 static const unsigned int rand_drbg_used_flags =
102 RAND_DRBG_FLAG_CTR_NO_DF | RAND_DRBG_FLAG_HMAC | RAND_DRBG_TYPE_FLAGS;
105 static RAND_DRBG *drbg_setup(RAND_DRBG *parent, int drbg_type);
107 static RAND_DRBG *rand_drbg_new(int secure,
112 static int is_ctr(int type)
115 case NID_aes_128_ctr:
116 case NID_aes_192_ctr:
117 case NID_aes_256_ctr:
124 static int is_digest(int type)
145 * Set/initialize |drbg| to be of type |type|, with optional |flags|.
147 * If |type| and |flags| are zero, use the defaults
149 * Returns 1 on success, 0 on failure.
151 int RAND_DRBG_set(RAND_DRBG *drbg, int type, unsigned int flags)
155 if (type == 0 && flags == 0) {
156 type = rand_drbg_type[RAND_DRBG_TYPE_MASTER];
157 flags = rand_drbg_flags[RAND_DRBG_TYPE_MASTER];
160 /* If set is called multiple times - clear the old one */
161 if (drbg->type != 0 && (type != drbg->type || flags != drbg->flags)) {
162 drbg->meth->uninstantiate(drbg);
163 rand_pool_free(drbg->adin_pool);
164 drbg->adin_pool = NULL;
167 drbg->state = DRBG_UNINITIALISED;
172 /* Uninitialized; that's okay. */
175 } else if (is_ctr(type)) {
176 ret = drbg_ctr_init(drbg);
177 } else if (is_digest(type)) {
178 if (flags & RAND_DRBG_FLAG_HMAC)
179 ret = drbg_hmac_init(drbg);
181 ret = drbg_hash_init(drbg);
186 RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
191 drbg->state = DRBG_ERROR;
192 RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
198 * Set/initialize default |type| and |flag| for new drbg instances.
200 * Returns 1 on success, 0 on failure.
202 int RAND_DRBG_set_defaults(int type, unsigned int flags)
205 if (!(is_digest(type) || is_ctr(type))) {
206 RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_TYPE);
210 if ((flags & ~rand_drbg_used_flags) != 0) {
211 RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_FLAGS);
215 all = ((flags & RAND_DRBG_TYPE_FLAGS) == 0);
216 if (all || (flags & RAND_DRBG_FLAG_MASTER) != 0) {
217 rand_drbg_type[RAND_DRBG_TYPE_MASTER] = type;
218 rand_drbg_flags[RAND_DRBG_TYPE_MASTER] = flags | RAND_DRBG_FLAG_MASTER;
220 if (all || (flags & RAND_DRBG_FLAG_PUBLIC) != 0) {
221 rand_drbg_type[RAND_DRBG_TYPE_PUBLIC] = type;
222 rand_drbg_flags[RAND_DRBG_TYPE_PUBLIC] = flags | RAND_DRBG_FLAG_PUBLIC;
224 if (all || (flags & RAND_DRBG_FLAG_PRIVATE) != 0) {
225 rand_drbg_type[RAND_DRBG_TYPE_PRIVATE] = type;
226 rand_drbg_flags[RAND_DRBG_TYPE_PRIVATE] = flags | RAND_DRBG_FLAG_PRIVATE;
233 * Allocate memory and initialize a new DRBG. The DRBG is allocated on
234 * the secure heap if |secure| is nonzero and the secure heap is enabled.
235 * The |parent|, if not NULL, will be used as random source for reseeding.
237 * Returns a pointer to the new DRBG instance on success, NULL on failure.
239 static RAND_DRBG *rand_drbg_new(int secure,
244 RAND_DRBG *drbg = secure ? OPENSSL_secure_zalloc(sizeof(*drbg))
245 : OPENSSL_zalloc(sizeof(*drbg));
248 RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
252 drbg->secure = secure && CRYPTO_secure_allocated(drbg);
253 drbg->fork_count = rand_fork_count;
254 drbg->parent = parent;
256 if (parent == NULL) {
258 drbg->get_entropy = rand_crngt_get_entropy;
259 drbg->cleanup_entropy = rand_crngt_cleanup_entropy;
261 drbg->get_entropy = rand_drbg_get_entropy;
262 drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
264 #ifndef RAND_DRBG_GET_RANDOM_NONCE
265 drbg->get_nonce = rand_drbg_get_nonce;
266 drbg->cleanup_nonce = rand_drbg_cleanup_nonce;
269 drbg->reseed_interval = master_reseed_interval;
270 drbg->reseed_time_interval = master_reseed_time_interval;
272 drbg->get_entropy = rand_drbg_get_entropy;
273 drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
275 * Do not provide nonce callbacks, the child DRBGs will
276 * obtain their nonce using random bits from the parent.
279 drbg->reseed_interval = slave_reseed_interval;
280 drbg->reseed_time_interval = slave_reseed_time_interval;
283 if (RAND_DRBG_set(drbg, type, flags) == 0)
286 if (parent != NULL) {
287 rand_drbg_lock(parent);
288 if (drbg->strength > parent->strength) {
290 * We currently don't support the algorithm from NIST SP 800-90C
291 * 10.1.2 to use a weaker DRBG as source
293 rand_drbg_unlock(parent);
294 RANDerr(RAND_F_RAND_DRBG_NEW, RAND_R_PARENT_STRENGTH_TOO_WEAK);
297 rand_drbg_unlock(parent);
303 RAND_DRBG_free(drbg);
308 RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
310 return rand_drbg_new(0, type, flags, parent);
313 RAND_DRBG *RAND_DRBG_secure_new(int type, unsigned int flags, RAND_DRBG *parent)
315 return rand_drbg_new(1, type, flags, parent);
319 * Uninstantiate |drbg| and free all memory.
321 void RAND_DRBG_free(RAND_DRBG *drbg)
326 if (drbg->meth != NULL)
327 drbg->meth->uninstantiate(drbg);
328 rand_pool_free(drbg->adin_pool);
329 CRYPTO_THREAD_lock_free(drbg->lock);
330 CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
333 OPENSSL_secure_clear_free(drbg, sizeof(*drbg));
335 OPENSSL_clear_free(drbg, sizeof(*drbg));
339 * Instantiate |drbg|, after it has been initialized. Use |pers| and
340 * |perslen| as prediction-resistance input.
342 * Requires that drbg->lock is already locked for write, if non-null.
344 * Returns 1 on success, 0 on failure.
346 int RAND_DRBG_instantiate(RAND_DRBG *drbg,
347 const unsigned char *pers, size_t perslen)
349 unsigned char *nonce = NULL, *entropy = NULL;
350 size_t noncelen = 0, entropylen = 0;
351 size_t min_entropy = drbg->strength;
352 size_t min_entropylen = drbg->min_entropylen;
353 size_t max_entropylen = drbg->max_entropylen;
355 if (perslen > drbg->max_perslen) {
356 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
357 RAND_R_PERSONALISATION_STRING_TOO_LONG);
361 if (drbg->meth == NULL) {
362 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
363 RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
367 if (drbg->state != DRBG_UNINITIALISED) {
368 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
369 drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
370 : RAND_R_ALREADY_INSTANTIATED);
374 drbg->state = DRBG_ERROR;
377 * NIST SP800-90Ar1 section 9.1 says you can combine getting the entropy
378 * and nonce in 1 call by increasing the entropy with 50% and increasing
379 * the minimum length to accomadate the length of the nonce.
380 * We do this in case a nonce is require and get_nonce is NULL.
382 if (drbg->min_noncelen > 0 && drbg->get_nonce == NULL) {
383 min_entropy += drbg->strength / 2;
384 min_entropylen += drbg->min_noncelen;
385 max_entropylen += drbg->max_noncelen;
388 drbg->reseed_next_counter = tsan_load(&drbg->reseed_prop_counter);
389 if (drbg->reseed_next_counter) {
390 drbg->reseed_next_counter++;
391 if(!drbg->reseed_next_counter)
392 drbg->reseed_next_counter = 1;
395 if (drbg->get_entropy != NULL)
396 entropylen = drbg->get_entropy(drbg, &entropy, min_entropy,
397 min_entropylen, max_entropylen, 0);
398 if (entropylen < min_entropylen
399 || entropylen > max_entropylen) {
400 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
404 if (drbg->min_noncelen > 0 && drbg->get_nonce != NULL) {
405 noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
406 drbg->min_noncelen, drbg->max_noncelen);
407 if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) {
408 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_NONCE);
413 if (!drbg->meth->instantiate(drbg, entropy, entropylen,
414 nonce, noncelen, pers, perslen)) {
415 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
419 drbg->state = DRBG_READY;
420 drbg->reseed_gen_counter = 1;
421 drbg->reseed_time = time(NULL);
422 tsan_store(&drbg->reseed_prop_counter, drbg->reseed_next_counter);
425 if (entropy != NULL && drbg->cleanup_entropy != NULL)
426 drbg->cleanup_entropy(drbg, entropy, entropylen);
427 if (nonce != NULL && drbg->cleanup_nonce != NULL)
428 drbg->cleanup_nonce(drbg, nonce, noncelen);
429 if (drbg->state == DRBG_READY)
435 * Uninstantiate |drbg|. Must be instantiated before it can be used.
437 * Requires that drbg->lock is already locked for write, if non-null.
439 * Returns 1 on success, 0 on failure.
441 int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
443 int index = -1, type, flags;
444 if (drbg->meth == NULL) {
445 drbg->state = DRBG_ERROR;
446 RANDerr(RAND_F_RAND_DRBG_UNINSTANTIATE,
447 RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
451 /* Clear the entire drbg->ctr struct, then reset some important
452 * members of the drbg->ctr struct (e.g. keysize, df_ks) to their
455 drbg->meth->uninstantiate(drbg);
457 /* The reset uses the default values for type and flags */
458 if (drbg->flags & RAND_DRBG_FLAG_MASTER)
459 index = RAND_DRBG_TYPE_MASTER;
460 else if (drbg->flags & RAND_DRBG_FLAG_PRIVATE)
461 index = RAND_DRBG_TYPE_PRIVATE;
462 else if (drbg->flags & RAND_DRBG_FLAG_PUBLIC)
463 index = RAND_DRBG_TYPE_PUBLIC;
466 flags = rand_drbg_flags[index];
467 type = rand_drbg_type[index];
472 return RAND_DRBG_set(drbg, type, flags);
476 * Reseed |drbg|, mixing in the specified data
478 * Requires that drbg->lock is already locked for write, if non-null.
480 * Returns 1 on success, 0 on failure.
482 int RAND_DRBG_reseed(RAND_DRBG *drbg,
483 const unsigned char *adin, size_t adinlen,
484 int prediction_resistance)
486 unsigned char *entropy = NULL;
487 size_t entropylen = 0;
489 if (drbg->state == DRBG_ERROR) {
490 RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
493 if (drbg->state == DRBG_UNINITIALISED) {
494 RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
500 } else if (adinlen > drbg->max_adinlen) {
501 RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
505 drbg->state = DRBG_ERROR;
507 drbg->reseed_next_counter = tsan_load(&drbg->reseed_prop_counter);
508 if (drbg->reseed_next_counter) {
509 drbg->reseed_next_counter++;
510 if(!drbg->reseed_next_counter)
511 drbg->reseed_next_counter = 1;
514 if (drbg->get_entropy != NULL)
515 entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
516 drbg->min_entropylen,
517 drbg->max_entropylen,
518 prediction_resistance);
519 if (entropylen < drbg->min_entropylen
520 || entropylen > drbg->max_entropylen) {
521 RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
525 if (!drbg->meth->reseed(drbg, entropy, entropylen, adin, adinlen))
528 drbg->state = DRBG_READY;
529 drbg->reseed_gen_counter = 1;
530 drbg->reseed_time = time(NULL);
531 tsan_store(&drbg->reseed_prop_counter, drbg->reseed_next_counter);
534 if (entropy != NULL && drbg->cleanup_entropy != NULL)
535 drbg->cleanup_entropy(drbg, entropy, entropylen);
536 if (drbg->state == DRBG_READY)
542 * Restart |drbg|, using the specified entropy or additional input
544 * Tries its best to get the drbg instantiated by all means,
545 * regardless of its current state.
547 * Optionally, a |buffer| of |len| random bytes can be passed,
548 * which is assumed to contain at least |entropy| bits of entropy.
550 * If |entropy| > 0, the buffer content is used as entropy input.
552 * If |entropy| == 0, the buffer content is used as additional input
554 * Returns 1 on success, 0 on failure.
556 * This function is used internally only.
558 int rand_drbg_restart(RAND_DRBG *drbg,
559 const unsigned char *buffer, size_t len, size_t entropy)
562 const unsigned char *adin = NULL;
565 if (drbg->seed_pool != NULL) {
566 RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
567 drbg->state = DRBG_ERROR;
568 rand_pool_free(drbg->seed_pool);
569 drbg->seed_pool = NULL;
573 if (buffer != NULL) {
575 if (drbg->max_entropylen < len) {
576 RANDerr(RAND_F_RAND_DRBG_RESTART,
577 RAND_R_ENTROPY_INPUT_TOO_LONG);
578 drbg->state = DRBG_ERROR;
582 if (entropy > 8 * len) {
583 RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_OUT_OF_RANGE);
584 drbg->state = DRBG_ERROR;
588 /* will be picked up by the rand_drbg_get_entropy() callback */
589 drbg->seed_pool = rand_pool_attach(buffer, len, entropy);
590 if (drbg->seed_pool == NULL)
593 if (drbg->max_adinlen < len) {
594 RANDerr(RAND_F_RAND_DRBG_RESTART,
595 RAND_R_ADDITIONAL_INPUT_TOO_LONG);
596 drbg->state = DRBG_ERROR;
604 /* repair error state */
605 if (drbg->state == DRBG_ERROR)
606 RAND_DRBG_uninstantiate(drbg);
608 /* repair uninitialized state */
609 if (drbg->state == DRBG_UNINITIALISED) {
610 /* reinstantiate drbg */
611 RAND_DRBG_instantiate(drbg,
612 (const unsigned char *) ossl_pers_string,
613 sizeof(ossl_pers_string) - 1);
614 /* already reseeded. prevent second reseeding below */
615 reseeded = (drbg->state == DRBG_READY);
618 /* refresh current state if entropy or additional input has been provided */
619 if (drbg->state == DRBG_READY) {
622 * mix in additional input without reseeding
624 * Similar to RAND_DRBG_reseed(), but the provided additional
625 * data |adin| is mixed into the current state without pulling
626 * entropy from the trusted entropy source using get_entropy().
627 * This is not a reseeding in the strict sense of NIST SP 800-90A.
629 drbg->meth->reseed(drbg, adin, adinlen, NULL, 0);
630 } else if (reseeded == 0) {
631 /* do a full reseeding if it has not been done yet above */
632 RAND_DRBG_reseed(drbg, NULL, 0, 0);
636 rand_pool_free(drbg->seed_pool);
637 drbg->seed_pool = NULL;
639 return drbg->state == DRBG_READY;
643 * Generate |outlen| bytes into the buffer at |out|. Reseed if we need
644 * to or if |prediction_resistance| is set. Additional input can be
645 * sent in |adin| and |adinlen|.
647 * Requires that drbg->lock is already locked for write, if non-null.
649 * Returns 1 on success, 0 on failure.
652 int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
653 int prediction_resistance,
654 const unsigned char *adin, size_t adinlen)
656 int reseed_required = 0;
658 if (drbg->state != DRBG_READY) {
659 /* try to recover from previous errors */
660 rand_drbg_restart(drbg, NULL, 0, 0);
662 if (drbg->state == DRBG_ERROR) {
663 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
666 if (drbg->state == DRBG_UNINITIALISED) {
667 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
672 if (outlen > drbg->max_request) {
673 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
676 if (adinlen > drbg->max_adinlen) {
677 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
681 if (drbg->fork_count != rand_fork_count) {
682 drbg->fork_count = rand_fork_count;
686 if (drbg->reseed_interval > 0) {
687 if (drbg->reseed_gen_counter > drbg->reseed_interval)
690 if (drbg->reseed_time_interval > 0) {
691 time_t now = time(NULL);
692 if (now < drbg->reseed_time
693 || now - drbg->reseed_time >= drbg->reseed_time_interval)
696 if (drbg->parent != NULL) {
697 unsigned int reseed_counter = tsan_load(&drbg->reseed_prop_counter);
698 if (reseed_counter > 0
699 && tsan_load(&drbg->parent->reseed_prop_counter)
704 if (reseed_required || prediction_resistance) {
705 if (!RAND_DRBG_reseed(drbg, adin, adinlen, prediction_resistance)) {
706 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
713 if (!drbg->meth->generate(drbg, out, outlen, adin, adinlen)) {
714 drbg->state = DRBG_ERROR;
715 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
719 drbg->reseed_gen_counter++;
725 * Generates |outlen| random bytes and stores them in |out|. It will
726 * using the given |drbg| to generate the bytes.
728 * Requires that drbg->lock is already locked for write, if non-null.
730 * Returns 1 on success 0 on failure.
732 int RAND_DRBG_bytes(RAND_DRBG *drbg, unsigned char *out, size_t outlen)
734 unsigned char *additional = NULL;
735 size_t additional_len;
739 if (drbg->adin_pool == NULL) {
742 drbg->adin_pool = rand_pool_new(0, 0, drbg->max_adinlen);
743 if (drbg->adin_pool == NULL)
747 additional_len = rand_drbg_get_additional_data(drbg->adin_pool,
750 for ( ; outlen > 0; outlen -= chunk, out += chunk) {
752 if (chunk > drbg->max_request)
753 chunk = drbg->max_request;
754 ret = RAND_DRBG_generate(drbg, out, chunk, 0, additional, additional_len);
761 if (additional != NULL)
762 rand_drbg_cleanup_additional_data(drbg->adin_pool, additional);
768 * Set the RAND_DRBG callbacks for obtaining entropy and nonce.
770 * Setting the callbacks is allowed only if the drbg has not been
771 * initialized yet. Otherwise, the operation will fail.
773 * Returns 1 on success, 0 on failure.
775 int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
776 RAND_DRBG_get_entropy_fn get_entropy,
777 RAND_DRBG_cleanup_entropy_fn cleanup_entropy,
778 RAND_DRBG_get_nonce_fn get_nonce,
779 RAND_DRBG_cleanup_nonce_fn cleanup_nonce)
781 if (drbg->state != DRBG_UNINITIALISED
782 || drbg->parent != NULL)
784 drbg->get_entropy = get_entropy;
785 drbg->cleanup_entropy = cleanup_entropy;
786 drbg->get_nonce = get_nonce;
787 drbg->cleanup_nonce = cleanup_nonce;
792 * Set the reseed interval.
794 * The drbg will reseed automatically whenever the number of generate
795 * requests exceeds the given reseed interval. If the reseed interval
796 * is 0, then this feature is disabled.
798 * Returns 1 on success, 0 on failure.
800 int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, unsigned int interval)
802 if (interval > MAX_RESEED_INTERVAL)
804 drbg->reseed_interval = interval;
809 * Set the reseed time interval.
811 * The drbg will reseed automatically whenever the time elapsed since
812 * the last reseeding exceeds the given reseed time interval. For safety,
813 * a reseeding will also occur if the clock has been reset to a smaller
816 * Returns 1 on success, 0 on failure.
818 int RAND_DRBG_set_reseed_time_interval(RAND_DRBG *drbg, time_t interval)
820 if (interval > MAX_RESEED_TIME_INTERVAL)
822 drbg->reseed_time_interval = interval;
827 * Set the default values for reseed (time) intervals of new DRBG instances
829 * The default values can be set independently for master DRBG instances
830 * (without a parent) and slave DRBG instances (with parent).
832 * Returns 1 on success, 0 on failure.
835 int RAND_DRBG_set_reseed_defaults(
836 unsigned int _master_reseed_interval,
837 unsigned int _slave_reseed_interval,
838 time_t _master_reseed_time_interval,
839 time_t _slave_reseed_time_interval
842 if (_master_reseed_interval > MAX_RESEED_INTERVAL
843 || _slave_reseed_interval > MAX_RESEED_INTERVAL)
846 if (_master_reseed_time_interval > MAX_RESEED_TIME_INTERVAL
847 || _slave_reseed_time_interval > MAX_RESEED_TIME_INTERVAL)
850 master_reseed_interval = _master_reseed_interval;
851 slave_reseed_interval = _slave_reseed_interval;
853 master_reseed_time_interval = _master_reseed_time_interval;
854 slave_reseed_time_interval = _slave_reseed_time_interval;
860 * Locks the given drbg. Locking a drbg which does not have locking
861 * enabled is considered a successful no-op.
863 * Returns 1 on success, 0 on failure.
865 int rand_drbg_lock(RAND_DRBG *drbg)
867 if (drbg->lock != NULL)
868 return CRYPTO_THREAD_write_lock(drbg->lock);
874 * Unlocks the given drbg. Unlocking a drbg which does not have locking
875 * enabled is considered a successful no-op.
877 * Returns 1 on success, 0 on failure.
879 int rand_drbg_unlock(RAND_DRBG *drbg)
881 if (drbg->lock != NULL)
882 return CRYPTO_THREAD_unlock(drbg->lock);
888 * Enables locking for the given drbg
890 * Locking can only be enabled if the random generator
891 * is in the uninitialized state.
893 * Returns 1 on success, 0 on failure.
895 int rand_drbg_enable_locking(RAND_DRBG *drbg)
897 if (drbg->state != DRBG_UNINITIALISED) {
898 RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
899 RAND_R_DRBG_ALREADY_INITIALIZED);
903 if (drbg->lock == NULL) {
904 if (drbg->parent != NULL && drbg->parent->lock == NULL) {
905 RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
906 RAND_R_PARENT_LOCKING_NOT_ENABLED);
910 drbg->lock = CRYPTO_THREAD_lock_new();
911 if (drbg->lock == NULL) {
912 RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
913 RAND_R_FAILED_TO_CREATE_LOCK);
922 * Get and set the EXDATA
924 int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
926 return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
929 void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
931 return CRYPTO_get_ex_data(&drbg->ex_data, idx);
936 * The following functions provide a RAND_METHOD that works on the
937 * global DRBG. They lock.
941 * Allocates a new global DRBG on the secure heap (if enabled) and
942 * initializes it with default settings.
944 * Returns a pointer to the new DRBG instance on success, NULL on failure.
946 static RAND_DRBG *drbg_setup(RAND_DRBG *parent, int drbg_type)
950 drbg = RAND_DRBG_secure_new(rand_drbg_type[drbg_type],
951 rand_drbg_flags[drbg_type], parent);
955 /* Only the master DRBG needs to have a lock */
956 if (parent == NULL && rand_drbg_enable_locking(drbg) == 0)
959 /* enable seed propagation */
960 tsan_store(&drbg->reseed_prop_counter, 1);
963 * Ignore instantiation error to support just-in-time instantiation.
965 * The state of the drbg will be checked in RAND_DRBG_generate() and
966 * an automatic recovery is attempted.
968 (void)RAND_DRBG_instantiate(drbg,
969 (const unsigned char *) ossl_pers_string,
970 sizeof(ossl_pers_string) - 1);
974 RAND_DRBG_free(drbg);
979 * Initialize the global DRBGs on first use.
980 * Returns 1 on success, 0 on failure.
982 DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init)
985 * ensure that libcrypto is initialized, otherwise the
986 * DRBG locks are not cleaned up properly
988 if (!OPENSSL_init_crypto(0, NULL))
991 if (!CRYPTO_THREAD_init_local(&private_drbg, NULL))
994 if (!CRYPTO_THREAD_init_local(&public_drbg, NULL))
997 master_drbg = drbg_setup(NULL, RAND_DRBG_TYPE_MASTER);
998 if (master_drbg == NULL)
1004 CRYPTO_THREAD_cleanup_local(&public_drbg);
1006 CRYPTO_THREAD_cleanup_local(&private_drbg);
1010 /* Clean up the global DRBGs before exit */
1011 void rand_drbg_cleanup_int(void)
1013 if (master_drbg != NULL) {
1014 RAND_DRBG_free(master_drbg);
1017 CRYPTO_THREAD_cleanup_local(&private_drbg);
1018 CRYPTO_THREAD_cleanup_local(&public_drbg);
1022 void drbg_delete_thread_state(void)
1026 drbg = CRYPTO_THREAD_get_local(&public_drbg);
1027 CRYPTO_THREAD_set_local(&public_drbg, NULL);
1028 RAND_DRBG_free(drbg);
1030 drbg = CRYPTO_THREAD_get_local(&private_drbg);
1031 CRYPTO_THREAD_set_local(&private_drbg, NULL);
1032 RAND_DRBG_free(drbg);
1035 /* Implements the default OpenSSL RAND_bytes() method */
1036 static int drbg_bytes(unsigned char *out, int count)
1039 RAND_DRBG *drbg = RAND_DRBG_get0_public();
1044 ret = RAND_DRBG_bytes(drbg, out, count);
1050 * Calculates the minimum length of a full entropy buffer
1051 * which is necessary to seed (i.e. instantiate) the DRBG
1054 size_t rand_drbg_seedlen(RAND_DRBG *drbg)
1057 * If no os entropy source is available then RAND_seed(buffer, bufsize)
1058 * is expected to succeed if and only if the buffer length satisfies
1059 * the following requirements, which follow from the calculations
1060 * in RAND_DRBG_instantiate().
1062 size_t min_entropy = drbg->strength;
1063 size_t min_entropylen = drbg->min_entropylen;
1066 * Extra entropy for the random nonce in the absence of a
1067 * get_nonce callback, see comment in RAND_DRBG_instantiate().
1069 if (drbg->min_noncelen > 0 && drbg->get_nonce == NULL) {
1070 min_entropy += drbg->strength / 2;
1071 min_entropylen += drbg->min_noncelen;
1075 * Convert entropy requirement from bits to bytes
1076 * (dividing by 8 without rounding upwards, because
1077 * all entropy requirements are divisible by 8).
1081 /* Return a value that satisfies both requirements */
1082 return min_entropy > min_entropylen ? min_entropy : min_entropylen;
1085 /* Implements the default OpenSSL RAND_add() method */
1086 static int drbg_add(const void *buf, int num, double randomness)
1089 RAND_DRBG *drbg = RAND_DRBG_get0_master();
1096 if (num < 0 || randomness < 0.0)
1099 rand_drbg_lock(drbg);
1100 seedlen = rand_drbg_seedlen(drbg);
1102 buflen = (size_t)num;
1106 * NIST SP-800-90A mandates that entropy *shall not* be provided
1107 * by the consuming application. By setting the randomness to zero,
1108 * we ensure that the buffer contents will be added to the internal
1109 * state of the DRBG only as additional data.
1111 * (NIST SP-800-90Ar1, Sections 9.1 and 9.2)
1115 if (buflen < seedlen || randomness < (double) seedlen) {
1116 #if defined(OPENSSL_RAND_SEED_NONE)
1118 * If no os entropy source is available, a reseeding will fail
1119 * inevitably. So we use a trick to mix the buffer contents into
1120 * the DRBG state without forcing a reseeding: we generate a
1121 * dummy random byte, using the buffer content as additional data.
1122 * Note: This won't work with RAND_DRBG_FLAG_CTR_NO_DF.
1124 unsigned char dummy[1];
1126 ret = RAND_DRBG_generate(drbg, dummy, sizeof(dummy), 0, buf, buflen);
1127 rand_drbg_unlock(drbg);
1131 * If an os entropy source is available then we declare the buffer content
1132 * as additional data by setting randomness to zero and trigger a regular
1139 if (randomness > (double)seedlen) {
1141 * The purpose of this check is to bound |randomness| by a
1142 * relatively small value in order to prevent an integer
1143 * overflow when multiplying by 8 in the rand_drbg_restart()
1144 * call below. Note that randomness is measured in bytes,
1145 * not bits, so this value corresponds to eight times the
1146 * security strength.
1148 randomness = (double)seedlen;
1151 ret = rand_drbg_restart(drbg, buf, buflen, (size_t)(8 * randomness));
1152 rand_drbg_unlock(drbg);
1157 /* Implements the default OpenSSL RAND_seed() method */
1158 static int drbg_seed(const void *buf, int num)
1160 return drbg_add(buf, num, num);
1163 /* Implements the default OpenSSL RAND_status() method */
1164 static int drbg_status(void)
1167 RAND_DRBG *drbg = RAND_DRBG_get0_master();
1172 rand_drbg_lock(drbg);
1173 ret = drbg->state == DRBG_READY ? 1 : 0;
1174 rand_drbg_unlock(drbg);
1179 * Get the master DRBG.
1180 * Returns pointer to the DRBG on success, NULL on failure.
1183 RAND_DRBG *RAND_DRBG_get0_master(void)
1185 if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1192 * Get the public DRBG.
1193 * Returns pointer to the DRBG on success, NULL on failure.
1195 RAND_DRBG *RAND_DRBG_get0_public(void)
1199 if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1202 drbg = CRYPTO_THREAD_get_local(&public_drbg);
1204 if (!ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND))
1206 drbg = drbg_setup(master_drbg, RAND_DRBG_TYPE_PUBLIC);
1207 CRYPTO_THREAD_set_local(&public_drbg, drbg);
1213 * Get the private DRBG.
1214 * Returns pointer to the DRBG on success, NULL on failure.
1216 RAND_DRBG *RAND_DRBG_get0_private(void)
1220 if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1223 drbg = CRYPTO_THREAD_get_local(&private_drbg);
1225 if (!ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND))
1227 drbg = drbg_setup(master_drbg, RAND_DRBG_TYPE_PRIVATE);
1228 CRYPTO_THREAD_set_local(&private_drbg, drbg);
1233 RAND_METHOD rand_meth = {
1242 RAND_METHOD *RAND_OpenSSL(void)