2 * Copyright 2011-2017 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
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"
18 static RAND_DRBG rand_drbg; /* The default global DRBG. */
19 static RAND_DRBG priv_drbg; /* The global private-key DRBG. */
21 /* NIST SP 800-90A DRBG recommends the use of a personalization string. */
22 static const char ossl_pers_string[] = "OpenSSL NIST SP 800-90A DRBG";
25 * Support framework for NIST SP 800-90A DRBG, AES-CTR mode.
26 * The RAND_DRBG is OpenSSL's pointer to an instance of the DRBG.
28 * The OpenSSL model is to have new and free functions, and that new
29 * does all initialization. That is not the NIST model, which has
30 * instantiation and un-instantiate, and re-use within a new/free
31 * lifecycle. (No doubt this comes from the desire to support hardware
32 * DRBG, where allocation of resources on something like an HSM is
33 * a much bigger deal than just re-setting an allocated resource.)
36 static CRYPTO_ONCE rand_drbg_init = CRYPTO_ONCE_STATIC_INIT;
38 static int drbg_setup(RAND_DRBG *drbg, const char *name);
41 * Set/initialize |drbg| to be of type |nid|, with optional |flags|.
42 * Return -2 if the type is not supported, 1 on success and -1 on
45 int RAND_DRBG_set(RAND_DRBG *drbg, int nid, unsigned int flags)
49 drbg->state = DRBG_UNINITIALISED;
55 RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
58 /* Uninitialized; that's okay. */
68 RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
73 * Allocate memory and initialize a new DRBG. The |parent|, if not
74 * NULL, will be used to auto-seed this RAND_DRBG as needed.
76 RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
78 RAND_DRBG *drbg = OPENSSL_zalloc(sizeof(*drbg));
81 RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
84 drbg->fork_count = rand_fork_count;
85 drbg->parent = parent;
86 if (RAND_DRBG_set(drbg, type, flags) < 0)
90 if (!RAND_DRBG_set_callbacks(drbg, rand_drbg_get_entropy,
91 rand_drbg_cleanup_entropy,
104 * Uninstantiate |drbg| and free all memory.
106 void RAND_DRBG_free(RAND_DRBG *drbg)
111 ctr_uninstantiate(drbg);
112 CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
113 OPENSSL_clear_free(drbg, sizeof(*drbg));
117 * Instantiate |drbg|, after it has been initialized. Use |pers| and
118 * |perslen| as prediction-resistance input.
120 int RAND_DRBG_instantiate(RAND_DRBG *drbg,
121 const unsigned char *pers, size_t perslen)
123 unsigned char *nonce = NULL, *entropy = NULL;
124 size_t noncelen = 0, entropylen = 0;
126 if (perslen > drbg->max_perslen) {
127 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
128 RAND_R_PERSONALISATION_STRING_TOO_LONG);
131 if (drbg->state != DRBG_UNINITIALISED) {
132 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
133 drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
134 : RAND_R_ALREADY_INSTANTIATED);
138 drbg->state = DRBG_ERROR;
139 if (drbg->get_entropy != NULL)
140 entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
141 drbg->min_entropylen, drbg->max_entropylen);
142 if (entropylen < drbg->min_entropylen
143 || entropylen > drbg->max_entropylen) {
144 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
148 if (drbg->max_noncelen > 0 && drbg->get_nonce != NULL) {
149 noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
150 drbg->min_noncelen, drbg->max_noncelen);
151 if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) {
152 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
153 RAND_R_ERROR_RETRIEVING_NONCE);
158 if (!ctr_instantiate(drbg, entropy, entropylen,
159 nonce, noncelen, pers, perslen)) {
160 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
164 drbg->state = DRBG_READY;
165 drbg->reseed_counter = 1;
168 if (entropy != NULL && drbg->cleanup_entropy != NULL)
169 drbg->cleanup_entropy(drbg, entropy, entropylen);
170 if (nonce != NULL && drbg->cleanup_nonce!= NULL )
171 drbg->cleanup_nonce(drbg, nonce, noncelen);
172 if (drbg->pool != NULL) {
173 if (drbg->state == DRBG_READY) {
174 RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
175 RAND_R_ERROR_ENTROPY_POOL_WAS_IGNORED);
176 drbg->state = DRBG_ERROR;
178 RAND_POOL_free(drbg->pool);
181 if (drbg->state == DRBG_READY)
187 * Uninstantiate |drbg|. Must be instantiated before it can be used.
189 int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
191 int ret = ctr_uninstantiate(drbg);
193 OPENSSL_cleanse(&drbg->ctr, sizeof(drbg->ctr));
194 drbg->state = DRBG_UNINITIALISED;
199 * Reseed |drbg|, mixing in the specified data
201 int RAND_DRBG_reseed(RAND_DRBG *drbg,
202 const unsigned char *adin, size_t adinlen)
204 unsigned char *entropy = NULL;
205 size_t entropylen = 0;
207 if (drbg->state == DRBG_ERROR) {
208 RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
211 if (drbg->state == DRBG_UNINITIALISED) {
212 RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
218 else if (adinlen > drbg->max_adinlen) {
219 RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
223 drbg->state = DRBG_ERROR;
224 if (drbg->get_entropy != NULL)
225 entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
226 drbg->min_entropylen, drbg->max_entropylen);
227 if (entropylen < drbg->min_entropylen
228 || entropylen > drbg->max_entropylen) {
229 RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
233 if (!ctr_reseed(drbg, entropy, entropylen, adin, adinlen))
235 drbg->state = DRBG_READY;
236 drbg->reseed_counter = 1;
239 if (entropy != NULL && drbg->cleanup_entropy != NULL)
240 drbg->cleanup_entropy(drbg, entropy, entropylen);
241 if (drbg->state == DRBG_READY)
247 * Restart |drbg|, using the specified entropy or additional input
249 * Tries its best to get the drbg instantiated by all means,
250 * regardless of its current state.
252 * Optionally, a |buffer| of |len| random bytes can be passed,
253 * which is assumed to contain at least |entropy| bits of entropy.
255 * If |entropy| > 0, the buffer content is used as entropy input.
257 * If |entropy| == 0, the buffer content is used as additional input
259 * Returns 1 on success, 0 on failure.
261 * This function is used internally only.
263 int rand_drbg_restart(RAND_DRBG *drbg,
264 const unsigned char *buffer, size_t len, size_t entropy)
267 const unsigned char *adin = NULL;
270 if (drbg->pool != NULL) {
271 RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
272 RAND_POOL_free(drbg->pool);
276 if (buffer != NULL) {
278 if (drbg->max_entropylen < len) {
279 RANDerr(RAND_F_RAND_DRBG_RESTART,
280 RAND_R_ENTROPY_INPUT_TOO_LONG);
284 if (entropy > 8 * len) {
285 RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_OUT_OF_RANGE);
289 /* will be picked up by the rand_drbg_get_entropy() callback */
290 drbg->pool = RAND_POOL_new(entropy, len, len);
291 if (drbg->pool == NULL)
294 RAND_POOL_add(drbg->pool, buffer, len, entropy);
296 if (drbg->max_adinlen < len) {
297 RANDerr(RAND_F_RAND_DRBG_RESTART,
298 RAND_R_ADDITIONAL_INPUT_TOO_LONG);
306 /* repair error state */
307 if (drbg->state == DRBG_ERROR)
308 RAND_DRBG_uninstantiate(drbg);
310 /* repair uninitialized state */
311 if (drbg->state == DRBG_UNINITIALISED) {
312 drbg_setup(drbg, NULL);
313 /* already reseeded. prevent second reseeding below */
314 reseeded = (drbg->state == DRBG_READY);
317 /* refresh current state if entropy or additional input has been provided */
318 if (drbg->state == DRBG_READY) {
321 * mix in additional input without reseeding
323 * Similar to RAND_DRBG_reseed(), but the provided additional
324 * data |adin| is mixed into the current state without pulling
325 * entropy from the trusted entropy source using get_entropy().
326 * This is not a reseeding in the strict sense of NIST SP 800-90A.
328 ctr_reseed(drbg, adin, adinlen, NULL, 0);
329 } else if (reseeded == 0) {
330 /* do a full reseeding if it has not been done yet above */
331 RAND_DRBG_reseed(drbg, NULL, 0);
335 /* check whether a given entropy pool was cleared properly during reseed */
336 if (drbg->pool != NULL) {
337 drbg->state = DRBG_ERROR;
338 RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
339 RAND_POOL_free(drbg->pool);
344 return drbg->state == DRBG_READY;
348 * Generate |outlen| bytes into the buffer at |out|. Reseed if we need
349 * to or if |prediction_resistance| is set. Additional input can be
350 * sent in |adin| and |adinlen|.
352 * Returns 1 on success, 0 on failure.
355 int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
356 int prediction_resistance,
357 const unsigned char *adin, size_t adinlen)
359 int reseed_required = 0;
361 if (drbg->state != DRBG_READY) {
362 /* try to recover from previous errors */
363 rand_drbg_restart(drbg, NULL, 0, 0);
365 if (drbg->state == DRBG_ERROR) {
366 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
369 if (drbg->state == DRBG_UNINITIALISED) {
370 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
375 if (outlen > drbg->max_request) {
376 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
379 if (adinlen > drbg->max_adinlen) {
380 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
384 if (drbg->fork_count != rand_fork_count) {
385 drbg->fork_count = rand_fork_count;
389 if (drbg->reseed_counter >= drbg->reseed_interval)
392 if (reseed_required || prediction_resistance) {
393 if (!RAND_DRBG_reseed(drbg, adin, adinlen)) {
394 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
401 if (!ctr_generate(drbg, out, outlen, adin, adinlen)) {
402 drbg->state = DRBG_ERROR;
403 RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
407 drbg->reseed_counter++;
413 * Set the RAND_DRBG callbacks for obtaining entropy and nonce.
415 * In the following, the signature and the semantics of the
416 * get_entropy() and cleanup_entropy() callbacks are explained.
420 * size_t get_entropy(RAND_DRBG *ctx,
421 * unsigned char **pout,
423 * size_t min_len, size_t max_len);
425 * This is a request to allocate and fill a buffer of size
426 * |min_len| <= size <= |max_len| (in bytes) which contains
427 * at least |entropy| bits of randomness. The buffer's address is
428 * to be returned in |*pout| and the number of collected
429 * randomness bytes (which may be less than the allocated size
430 * of the buffer) as return value.
432 * If the callback fails to acquire at least |entropy| bits of
433 * randomness, it shall return a buffer length of 0.
437 * void cleanup_entropy(RAND_DRBG *ctx,
438 * unsigned char *out, size_t outlen);
440 * A request to clear and free the buffer allocated by get_entropy().
441 * The values |out| and |outlen| are expected to be the random buffer's
442 * address and length, as returned by the get_entropy() callback.
444 * GET_NONCE, CLEANUP_NONCE
446 * Signature and semantics of the get_nonce() and cleanup_nonce()
447 * callbacks are analogous to get_entropy() and cleanup_entropy().
448 * Currently, the nonce is used only for the known answer tests.
450 int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
451 RAND_DRBG_get_entropy_fn get_entropy,
452 RAND_DRBG_cleanup_entropy_fn cleanup_entropy,
453 RAND_DRBG_get_nonce_fn get_nonce,
454 RAND_DRBG_cleanup_nonce_fn cleanup_nonce)
456 if (drbg->state != DRBG_UNINITIALISED)
458 drbg->get_entropy = get_entropy;
459 drbg->cleanup_entropy = cleanup_entropy;
460 drbg->get_nonce = get_nonce;
461 drbg->cleanup_nonce = cleanup_nonce;
466 * Set the reseed interval.
468 int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, int interval)
470 if (interval < 0 || interval > MAX_RESEED)
472 drbg->reseed_interval = interval;
477 * Get and set the EXDATA
479 int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
481 return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
484 void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
486 return CRYPTO_get_ex_data(&drbg->ex_data, idx);
491 * The following functions provide a RAND_METHOD that works on the
492 * global DRBG. They lock.
496 * Initializes the DRBG with default settings.
497 * For global DRBGs a global lock is created with the given name
498 * Returns 1 on success, 0 on failure
500 static int drbg_setup(RAND_DRBG *drbg, const char *name)
505 if (drbg->lock != NULL) {
506 RANDerr(RAND_F_DRBG_SETUP, ERR_R_INTERNAL_ERROR);
510 drbg->lock = CRYPTO_THREAD_glock_new(name);
511 if (drbg->lock == NULL) {
512 RANDerr(RAND_F_DRBG_SETUP, RAND_R_FAILED_TO_CREATE_LOCK);
517 ret &= RAND_DRBG_set(drbg,
518 RAND_DRBG_NID, RAND_DRBG_FLAG_CTR_USE_DF) == 1;
519 ret &= RAND_DRBG_set_callbacks(drbg, rand_drbg_get_entropy,
520 rand_drbg_cleanup_entropy, NULL, NULL) == 1;
522 * Ignore instantiation error so support just-in-time instantiation.
524 * The state of the drbg will be checked in RAND_DRBG_generate() and
525 * an automatic recovery is attempted.
527 RAND_DRBG_instantiate(drbg,
528 (const unsigned char *) ossl_pers_string,
529 sizeof(ossl_pers_string) - 1);
534 * Initialize the global DRBGs on first use.
535 * Returns 1 on success, 0 on failure.
537 DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init)
541 ret &= drbg_setup(&rand_drbg, "rand_drbg");
542 ret &= drbg_setup(&priv_drbg, "priv_drbg");
547 /* Cleans up the given global DRBG */
548 static void drbg_cleanup(RAND_DRBG *drbg)
550 CRYPTO_THREAD_lock_free(drbg->lock);
551 RAND_DRBG_uninstantiate(drbg);
554 /* Clean up the global DRBGs before exit */
555 void rand_drbg_cleanup_int(void)
557 drbg_cleanup(&rand_drbg);
558 drbg_cleanup(&priv_drbg);
561 /* Implements the default OpenSSL RAND_bytes() method */
562 static int drbg_bytes(unsigned char *out, int count)
566 RAND_DRBG *drbg = RAND_DRBG_get0_global();
571 CRYPTO_THREAD_write_lock(drbg->lock);
572 if (drbg->state == DRBG_UNINITIALISED)
575 for ( ; count > 0; count -= chunk, out += chunk) {
577 if (chunk > drbg->max_request)
578 chunk = drbg->max_request;
579 ret = RAND_DRBG_generate(drbg, out, chunk, 0, NULL, 0);
586 CRYPTO_THREAD_unlock(drbg->lock);
590 /* Implements the default OpenSSL RAND_add() method */
591 static int drbg_add(const void *buf, int num, double randomness)
594 RAND_DRBG *drbg = RAND_DRBG_get0_global();
599 if (num < 0 || randomness < 0.0)
602 if (randomness > (double)drbg->max_entropylen) {
604 * The purpose of this check is to bound |randomness| by a
605 * relatively small value in order to prevent an integer
606 * overflow when multiplying by 8 in the rand_drbg_restart()
612 CRYPTO_THREAD_write_lock(drbg->lock);
613 ret = rand_drbg_restart(drbg, buf,
614 (size_t)(unsigned int)num,
615 (size_t)(8*randomness));
616 CRYPTO_THREAD_unlock(drbg->lock);
621 /* Implements the default OpenSSL RAND_seed() method */
622 static int drbg_seed(const void *buf, int num)
624 return drbg_add(buf, num, num);
627 /* Implements the default OpenSSL RAND_status() method */
628 static int drbg_status(void)
631 RAND_DRBG *drbg = RAND_DRBG_get0_global();
636 CRYPTO_THREAD_write_lock(drbg->lock);
637 ret = drbg->state == DRBG_READY ? 1 : 0;
638 CRYPTO_THREAD_unlock(drbg->lock);
643 * Get the global public DRBG.
644 * Returns pointer to the DRBG on success, NULL on failure.
646 RAND_DRBG *RAND_DRBG_get0_global(void)
648 if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
655 * Get the global private DRBG.
656 * Returns pointer to the DRBG on success, NULL on failure.
658 RAND_DRBG *RAND_DRBG_get0_priv_global(void)
660 if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
666 RAND_METHOD rand_meth = {
675 RAND_METHOD *RAND_OpenSSL(void)