2 * Copyright 1995-2016 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"
19 #ifndef OPENSSL_NO_ENGINE
20 /* non-NULL if default_RAND_meth is ENGINE-provided */
21 static ENGINE *funct_ref;
22 static CRYPTO_RWLOCK *rand_engine_lock;
24 static CRYPTO_RWLOCK *rand_meth_lock;
25 static const RAND_METHOD *default_RAND_meth;
26 static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT;
27 RAND_BYTES_BUFFER rand_bytes;
30 #ifdef OPENSSL_RAND_SEED_RDTSC
32 * IMPORTANT NOTE: It is not currently possible to use this code
33 * because we are not sure about the amount of randomness. Some
34 * SP900 tests have been run, but there is internal skepticism.
35 * So for now this code is not used.
37 # error "RDTSC enabled? Should not be possible!"
40 * Since we get some randomness from the low-order bits of the
41 * high-speec clock, it can help. But don't return a status since
42 * it's not sufficient to indicate whether or not the seeding was
45 void rand_read_tsc(RAND_poll_fn cb, void *arg)
50 for (i = 0; i < 10; i++) {
51 c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
57 #ifdef OPENSSL_RAND_SEED_RDCPU
58 size_t OPENSSL_ia32_rdseed(void);
59 size_t OPENSSL_ia32_rdrand(void);
61 extern unsigned int OPENSSL_ia32cap_P[];
63 int rand_read_cpu(RAND_poll_fn cb, void *arg)
67 /* If RDSEED is available, use that. */
68 if ((OPENSSL_ia32cap_P[1] & (1 << 18)) != 0) {
69 for (i = 0; i < RANDOMNESS_NEEDED; i += sizeof(s)) {
70 s = OPENSSL_ia32_rdseed();
73 cb(arg, &s, (int)sizeof(s), sizeof(s));
75 if (i >= RANDOMNESS_NEEDED)
79 /* Second choice is RDRAND. */
80 if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
81 for (i = 0; i < RANDOMNESS_NEEDED; i += sizeof(s)) {
82 s = OPENSSL_ia32_rdrand();
85 cb(arg, &s, (int)sizeof(s), sizeof(s));
87 if (i >= RANDOMNESS_NEEDED)
97 * DRBG has two sets of callbacks; we only discuss the "entropy" one
98 * here. When the DRBG needs additional randomness bits (called entropy
99 * in the NIST document), it calls the get_entropy callback which fills in
100 * a pointer and returns the number of bytes. When the DRBG is finished with
101 * the buffer, it calls the cleanup_entropy callback, with the value of
102 * the buffer that the get_entropy callback filled in.
104 * Get entropy from the system, via RAND_poll if needed. The |entropy|
105 * is the bits of randomness required, and is expected to fit into a buffer
106 * of |min_len|..|max__len| size. We assume we're getting high-quality
107 * randomness from the system, and that |min_len| bytes will do.
109 size_t drbg_entropy_from_system(RAND_DRBG *drbg,
110 unsigned char **pout,
111 int entropy, size_t min_len, size_t max_len)
116 if (min_len > (size_t)drbg->size) {
117 /* Should not happen. See comment near RANDOMNESS_NEEDED. */
118 min_len = drbg->size;
122 /* Re-use what we have. */
123 *pout = drbg->randomness;
127 /* If we don't have enough, try to get more. */
128 CRYPTO_THREAD_write_lock(rand_bytes.lock);
129 for (i = RAND_POLL_RETRIES; rand_bytes.curr < min_len && --i >= 0; ) {
130 CRYPTO_THREAD_unlock(rand_bytes.lock);
132 CRYPTO_THREAD_write_lock(rand_bytes.lock);
135 /* Get desired amount, but no more than we have. */
136 if (min_len > rand_bytes.curr)
137 min_len = rand_bytes.curr;
139 memcpy(drbg->randomness, rand_bytes.buff, min_len);
141 /* Update amount left and shift it down. */
142 rand_bytes.curr -= min_len;
143 if (rand_bytes.curr != 0)
144 memmove(rand_bytes.buff, &rand_bytes.buff[min_len], rand_bytes.curr);
146 CRYPTO_THREAD_unlock(rand_bytes.lock);
147 *pout = drbg->randomness;
151 size_t drbg_entropy_from_parent(RAND_DRBG *drbg,
152 unsigned char **pout,
153 int entropy, size_t min_len, size_t max_len)
157 if (min_len > (size_t)drbg->size) {
158 /* Should not happen. See comment near RANDOMNESS_NEEDED. */
159 min_len = drbg->size;
162 /* Get random from parent, include our state as additional input. */
163 st = RAND_DRBG_generate(drbg->parent, drbg->randomness, min_len, 0,
164 (unsigned char *)drbg, sizeof(*drbg));
168 *pout = drbg->randomness;
172 void drbg_release_entropy(RAND_DRBG *drbg, unsigned char *out)
175 OPENSSL_cleanse(drbg->randomness, drbg->size);
180 * Set up a global DRBG.
182 static int setup_drbg(RAND_DRBG *drbg)
186 drbg->lock = CRYPTO_THREAD_lock_new();
187 ret &= drbg->lock != NULL;
188 drbg->size = RANDOMNESS_NEEDED;
189 drbg->randomness = OPENSSL_malloc(drbg->size);
190 ret &= drbg->randomness != NULL;
191 /* If you change these parameters, see RANDOMNESS_NEEDED */
192 ret &= RAND_DRBG_set(drbg,
193 NID_aes_128_ctr, RAND_DRBG_FLAG_CTR_USE_DF) == 1;
194 ret &= RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_system,
195 drbg_release_entropy, NULL, NULL) == 1;
199 static void free_drbg(RAND_DRBG *drbg)
201 CRYPTO_THREAD_lock_free(drbg->lock);
202 OPENSSL_clear_free(drbg->randomness, drbg->size);
203 RAND_DRBG_uninstantiate(drbg);
211 DEFINE_RUN_ONCE_STATIC(do_rand_init)
215 #ifndef OPENSSL_NO_ENGINE
216 rand_engine_lock = CRYPTO_THREAD_lock_new();
217 ret &= rand_engine_lock != NULL;
219 rand_meth_lock = CRYPTO_THREAD_lock_new();
220 ret &= rand_meth_lock != NULL;
222 rand_bytes.lock = CRYPTO_THREAD_lock_new();
223 ret &= rand_bytes.lock != NULL;
225 rand_bytes.size = MAX_RANDOMNESS_HELD;
226 /* TODO: Should this be secure malloc? */
227 rand_bytes.buff = malloc(rand_bytes.size);
229 ret &= rand_bytes.buff != NULL;
230 ret &= setup_drbg(&rand_drbg);
231 ret &= setup_drbg(&priv_drbg);
235 void rand_cleanup_int(void)
237 const RAND_METHOD *meth = default_RAND_meth;
239 if (meth != NULL && meth->cleanup != NULL)
241 RAND_set_rand_method(NULL);
242 #ifndef OPENSSL_NO_ENGINE
243 CRYPTO_THREAD_lock_free(rand_engine_lock);
245 CRYPTO_THREAD_lock_free(rand_meth_lock);
246 CRYPTO_THREAD_lock_free(rand_bytes.lock);
247 OPENSSL_clear_free(rand_bytes.buff, rand_bytes.size);
248 free_drbg(&rand_drbg);
249 free_drbg(&priv_drbg);
253 * RAND_poll_ex() gets a function pointer to call when it has random bytes.
254 * RAND_poll() sets the function pointer to be a wrapper that calls RAND_add().
256 static void call_rand_add(void* arg, const void *buf, int num, double r)
258 RAND_add(buf, num, r);
263 return RAND_poll_ex(call_rand_add, NULL);
266 int RAND_set_rand_method(const RAND_METHOD *meth)
268 if (!RUN_ONCE(&rand_init, do_rand_init))
271 CRYPTO_THREAD_write_lock(rand_meth_lock);
272 #ifndef OPENSSL_NO_ENGINE
273 ENGINE_finish(funct_ref);
276 default_RAND_meth = meth;
277 CRYPTO_THREAD_unlock(rand_meth_lock);
281 const RAND_METHOD *RAND_get_rand_method(void)
283 const RAND_METHOD *tmp_meth = NULL;
285 if (!RUN_ONCE(&rand_init, do_rand_init))
288 CRYPTO_THREAD_write_lock(rand_meth_lock);
289 if (default_RAND_meth == NULL) {
290 #ifndef OPENSSL_NO_ENGINE
293 /* If we have an engine that can do RAND, use it. */
294 if ((e = ENGINE_get_default_RAND()) != NULL
295 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
297 default_RAND_meth = tmp_meth;
300 default_RAND_meth = &rand_meth;
303 default_RAND_meth = &rand_meth;
306 tmp_meth = default_RAND_meth;
307 CRYPTO_THREAD_unlock(rand_meth_lock);
311 #ifndef OPENSSL_NO_ENGINE
312 int RAND_set_rand_engine(ENGINE *engine)
314 const RAND_METHOD *tmp_meth = NULL;
316 if (!RUN_ONCE(&rand_init, do_rand_init))
319 if (engine != NULL) {
320 if (!ENGINE_init(engine))
322 tmp_meth = ENGINE_get_RAND(engine);
323 if (tmp_meth == NULL) {
324 ENGINE_finish(engine);
328 CRYPTO_THREAD_write_lock(rand_engine_lock);
329 /* This function releases any prior ENGINE so call it first */
330 RAND_set_rand_method(tmp_meth);
332 CRYPTO_THREAD_unlock(rand_engine_lock);
337 void RAND_seed(const void *buf, int num)
339 const RAND_METHOD *meth = RAND_get_rand_method();
341 if (meth->seed != NULL)
342 meth->seed(buf, num);
345 void RAND_add(const void *buf, int num, double randomness)
347 const RAND_METHOD *meth = RAND_get_rand_method();
349 if (meth->add != NULL)
350 meth->add(buf, num, randomness);
354 * This function is not part of RAND_METHOD, so if we're not using
355 * the default method, then just call RAND_bytes(). Otherwise make
356 * sure we're instantiated and use the private DRBG.
358 int RAND_priv_bytes(unsigned char *buf, int num)
360 const RAND_METHOD *meth = RAND_get_rand_method();
362 if (meth != RAND_OpenSSL())
363 return RAND_bytes(buf, num);
365 if (priv_drbg.state == DRBG_UNINITIALISED
366 && RAND_DRBG_instantiate(&priv_drbg, NULL, 0) == 0)
368 return RAND_DRBG_generate(&priv_drbg, buf, num, 0, NULL, 0);
372 int RAND_bytes(unsigned char *buf, int num)
374 const RAND_METHOD *meth = RAND_get_rand_method();
376 if (meth->bytes != NULL)
377 return meth->bytes(buf, num);
378 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
382 #if OPENSSL_API_COMPAT < 0x10100000L
383 int RAND_pseudo_bytes(unsigned char *buf, int num)
385 const RAND_METHOD *meth = RAND_get_rand_method();
387 if (meth->pseudorand != NULL)
388 return meth->pseudorand(buf, num);
393 int RAND_status(void)
395 const RAND_METHOD *meth = RAND_get_rand_method();
397 if (meth->status != NULL)
398 return meth->status();