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;
29 #ifdef OPENSSL_RAND_SEED_RDTSC
31 * IMPORTANT NOTE: It is not currently possible to use this code
32 * because we are not sure about the amount of randomness. Some
33 * SP900 tests have been run, but there is internal skepticism.
34 * So for now this code is not used.
36 # error "RDTSC enabled? Should not be possible!"
39 * Since we get some randomness from the low-order bits of the
40 * high-speec clock, it can help. But don't return a status since
41 * it's not sufficient to indicate whether or not the seeding was
44 void rand_read_tsc(RAND_poll_fn cb, void *arg)
49 for (i = 0; i < 10; i++) {
50 c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
56 #ifdef OPENSSL_RAND_SEED_RDCPU
57 size_t OPENSSL_ia32_rdseed(void);
58 size_t OPENSSL_ia32_rdrand(void);
60 extern unsigned int OPENSSL_ia32cap_P[];
62 int rand_read_cpu(RAND_poll_fn cb, void *arg)
66 /* If RDSEED is available, use that. */
67 if ((OPENSSL_ia32cap_P[1] & (1 << 18)) != 0) {
68 for (i = 0; i < RANDOMNESS_NEEDED; i += sizeof(s)) {
69 s = OPENSSL_ia32_rdseed();
72 cb(arg, &s, (int)sizeof(s), sizeof(s));
74 if (i >= RANDOMNESS_NEEDED)
78 /* Second choice is RDRAND. */
79 if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
80 for (i = 0; i < RANDOMNESS_NEEDED; i += sizeof(s)) {
81 s = OPENSSL_ia32_rdrand();
84 cb(arg, &s, (int)sizeof(s), sizeof(s));
86 if (i >= RANDOMNESS_NEEDED)
96 * DRBG has two sets of callbacks; we only discuss the "entropy" one
97 * here. When the DRBG needs additional randomness bits (called entropy
98 * in the NIST document), it calls the get_entropy callback which fills in
99 * a pointer and returns the number of bytes. When the DRBG is finished with
100 * the buffer, it calls the cleanup_entropy callback, with the value of
101 * the buffer that the get_entropy callback filled in.
103 * Get entropy from the system, via RAND_poll if needed. The |entropy|
104 * is the bits of randomness required, and is expected to fit into a buffer
105 * of |min_len|..|max__len| size. We assume we're getting high-quality
106 * randomness from the system, and that |min_len| bytes will do.
108 size_t drbg_entropy_from_system(RAND_DRBG *drbg,
109 unsigned char **pout,
110 int entropy, size_t min_len, size_t max_len)
115 if (min_len > (size_t)drbg->size) {
116 /* Should not happen. See comment near RANDOMNESS_NEEDED. */
117 min_len = drbg->size;
121 /* Re-use what we have. */
122 *pout = drbg->randomness;
126 /* If we don't have enough, try to get more. */
127 CRYPTO_THREAD_write_lock(rand_bytes.lock);
128 for (i = RAND_POLL_RETRIES; rand_bytes.curr < min_len && --i >= 0; ) {
129 CRYPTO_THREAD_unlock(rand_bytes.lock);
131 CRYPTO_THREAD_write_lock(rand_bytes.lock);
134 /* Get desired amount, but no more than we have. */
135 if (min_len > rand_bytes.curr)
136 min_len = rand_bytes.curr;
138 memcpy(drbg->randomness, rand_bytes.buff, min_len);
140 /* Update amount left and shift it down. */
141 rand_bytes.curr -= min_len;
142 if (rand_bytes.curr != 0)
143 memmove(rand_bytes.buff, &rand_bytes.buff[min_len], rand_bytes.curr);
145 CRYPTO_THREAD_unlock(rand_bytes.lock);
146 *pout = drbg->randomness;
150 size_t drbg_entropy_from_parent(RAND_DRBG *drbg,
151 unsigned char **pout,
152 int entropy, size_t min_len, size_t max_len)
156 if (min_len > (size_t)drbg->size) {
157 /* Should not happen. See comment near RANDOMNESS_NEEDED. */
158 min_len = drbg->size;
161 /* Get random from parent, include our state as additional input. */
162 st = RAND_DRBG_generate(drbg->parent, drbg->randomness, min_len, 0,
163 (unsigned char *)drbg, sizeof(*drbg));
167 *pout = drbg->randomness;
171 void drbg_release_entropy(RAND_DRBG *drbg, unsigned char *out)
174 OPENSSL_cleanse(drbg->randomness, drbg->size);
179 * Set up a global DRBG.
181 static int setup_drbg(RAND_DRBG *drbg)
185 drbg->lock = CRYPTO_THREAD_lock_new();
186 ret &= drbg->lock != NULL;
187 drbg->size = RANDOMNESS_NEEDED;
188 drbg->randomness = OPENSSL_malloc(drbg->size);
189 ret &= drbg->randomness != NULL;
190 /* If you change these parameters, see RANDOMNESS_NEEDED */
191 ret &= RAND_DRBG_set(drbg,
192 NID_aes_128_ctr, RAND_DRBG_FLAG_CTR_USE_DF) == 1;
193 ret &= RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_system,
194 drbg_release_entropy, NULL, NULL) == 1;
198 static void free_drbg(RAND_DRBG *drbg)
200 CRYPTO_THREAD_lock_free(drbg->lock);
201 OPENSSL_clear_free(drbg->randomness, drbg->size);
202 RAND_DRBG_uninstantiate(drbg);
205 DEFINE_RUN_ONCE_STATIC(do_rand_init)
209 #ifndef OPENSSL_NO_ENGINE
210 rand_engine_lock = CRYPTO_THREAD_lock_new();
211 ret &= rand_engine_lock != NULL;
213 rand_meth_lock = CRYPTO_THREAD_lock_new();
214 ret &= rand_meth_lock != NULL;
216 rand_bytes.lock = CRYPTO_THREAD_lock_new();
217 ret &= rand_bytes.lock != NULL;
219 rand_bytes.size = MAX_RANDOMNESS_HELD;
220 /* TODO: Should this be secure malloc? */
221 rand_bytes.buff = malloc(rand_bytes.size);
223 ret &= rand_bytes.buff != NULL;
224 ret &= setup_drbg(&rand_drbg);
225 ret &= setup_drbg(&priv_drbg);
230 void rand_cleanup_int(void)
232 const RAND_METHOD *meth = default_RAND_meth;
234 if (meth != NULL && meth->cleanup != NULL)
236 RAND_set_rand_method(NULL);
237 #ifndef OPENSSL_NO_ENGINE
238 CRYPTO_THREAD_lock_free(rand_engine_lock);
240 CRYPTO_THREAD_lock_free(rand_meth_lock);
241 CRYPTO_THREAD_lock_free(rand_bytes.lock);
242 OPENSSL_clear_free(rand_bytes.buff, rand_bytes.size);
243 free_drbg(&rand_drbg);
244 free_drbg(&priv_drbg);
248 * RAND_poll_ex() gets a function pointer to call when it has random bytes.
249 * RAND_poll() sets the function pointer to be a wrapper that calls RAND_add().
251 static void call_rand_add(void* arg, const void *buf, int num, double r)
253 RAND_add(buf, num, r);
258 return RAND_poll_ex(call_rand_add, NULL);
261 int RAND_set_rand_method(const RAND_METHOD *meth)
263 if (!RUN_ONCE(&rand_init, do_rand_init))
266 CRYPTO_THREAD_write_lock(rand_meth_lock);
267 #ifndef OPENSSL_NO_ENGINE
268 ENGINE_finish(funct_ref);
271 default_RAND_meth = meth;
272 CRYPTO_THREAD_unlock(rand_meth_lock);
276 const RAND_METHOD *RAND_get_rand_method(void)
278 const RAND_METHOD *tmp_meth = NULL;
280 if (!RUN_ONCE(&rand_init, do_rand_init))
283 CRYPTO_THREAD_write_lock(rand_meth_lock);
284 if (default_RAND_meth == NULL) {
285 #ifndef OPENSSL_NO_ENGINE
288 /* If we have an engine that can do RAND, use it. */
289 if ((e = ENGINE_get_default_RAND()) != NULL
290 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
292 default_RAND_meth = tmp_meth;
295 default_RAND_meth = &rand_meth;
298 default_RAND_meth = &rand_meth;
301 tmp_meth = default_RAND_meth;
302 CRYPTO_THREAD_unlock(rand_meth_lock);
306 #ifndef OPENSSL_NO_ENGINE
307 int RAND_set_rand_engine(ENGINE *engine)
309 const RAND_METHOD *tmp_meth = NULL;
311 if (!RUN_ONCE(&rand_init, do_rand_init))
314 if (engine != NULL) {
315 if (!ENGINE_init(engine))
317 tmp_meth = ENGINE_get_RAND(engine);
318 if (tmp_meth == NULL) {
319 ENGINE_finish(engine);
323 CRYPTO_THREAD_write_lock(rand_engine_lock);
324 /* This function releases any prior ENGINE so call it first */
325 RAND_set_rand_method(tmp_meth);
327 CRYPTO_THREAD_unlock(rand_engine_lock);
332 void RAND_seed(const void *buf, int num)
334 const RAND_METHOD *meth = RAND_get_rand_method();
336 if (meth->seed != NULL)
337 meth->seed(buf, num);
340 void RAND_add(const void *buf, int num, double randomness)
342 const RAND_METHOD *meth = RAND_get_rand_method();
344 if (meth->add != NULL)
345 meth->add(buf, num, randomness);
349 * This function is not part of RAND_METHOD, so if we're not using
350 * the default method, then just call RAND_bytes(). Otherwise make
351 * sure we're instantiated and use the private DRBG.
353 int RAND_priv_bytes(unsigned char *buf, int num)
355 const RAND_METHOD *meth = RAND_get_rand_method();
357 if (meth != RAND_OpenSSL())
358 return RAND_bytes(buf, num);
360 if (priv_drbg.state == DRBG_UNINITIALISED
361 && RAND_DRBG_instantiate(&priv_drbg, NULL, 0) == 0)
363 return RAND_DRBG_generate(&priv_drbg, buf, num, 0, NULL, 0);
367 int RAND_bytes(unsigned char *buf, int num)
369 const RAND_METHOD *meth = RAND_get_rand_method();
371 if (meth->bytes != NULL)
372 return meth->bytes(buf, num);
373 RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
377 #if OPENSSL_API_COMPAT < 0x10100000L
378 int RAND_pseudo_bytes(unsigned char *buf, int num)
380 const RAND_METHOD *meth = RAND_get_rand_method();
382 if (meth->pseudorand != NULL)
383 return meth->pseudorand(buf, num);
388 int RAND_status(void)
390 const RAND_METHOD *meth = RAND_get_rand_method();
392 if (meth->status != NULL)
393 return meth->status();