1 /* crypto/rand/md_rand.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to. The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 * must display the following acknowledgement:
33 * "This product includes cryptographic software written by
34 * Eric Young (eay@cryptsoft.com)"
35 * The word 'cryptographic' can be left out if the rouines from the library
36 * being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed. i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
58 /* ====================================================================
59 * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved.
61 * Redistribution and use in source and binary forms, with or without
62 * modification, are permitted provided that the following conditions
65 * 1. Redistributions of source code must retain the above copyright
66 * notice, this list of conditions and the following disclaimer.
68 * 2. Redistributions in binary form must reproduce the above copyright
69 * notice, this list of conditions and the following disclaimer in
70 * the documentation and/or other materials provided with the
73 * 3. All advertising materials mentioning features or use of this
74 * software must display the following acknowledgment:
75 * "This product includes software developed by the OpenSSL Project
76 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
78 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
79 * endorse or promote products derived from this software without
80 * prior written permission. For written permission, please contact
81 * openssl-core@openssl.org.
83 * 5. Products derived from this software may not be called "OpenSSL"
84 * nor may "OpenSSL" appear in their names without prior written
85 * permission of the OpenSSL Project.
87 * 6. Redistributions of any form whatsoever must retain the following
89 * "This product includes software developed by the OpenSSL Project
90 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
92 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
93 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
94 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
95 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
96 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
97 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
98 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
99 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
100 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
101 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
102 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
103 * OF THE POSSIBILITY OF SUCH DAMAGE.
104 * ====================================================================
106 * This product includes cryptographic software written by Eric Young
107 * (eay@cryptsoft.com). This product includes software written by Tim
108 * Hudson (tjh@cryptsoft.com).
112 #define OPENSSL_FIPSEVP
126 #include <openssl/crypto.h>
127 #include <openssl/rand.h>
128 #include "rand_lcl.h"
130 #include <openssl/err.h>
136 /* #define PREDICT 1 */
138 #define STATE_SIZE 1023
139 static size_t state_num = 0, state_index = 0;
140 static unsigned char state[STATE_SIZE + MD_DIGEST_LENGTH];
141 static unsigned char md[MD_DIGEST_LENGTH];
142 static long md_count[2] = { 0, 0 };
144 static double entropy = 0;
145 static int initialized = 0;
147 static unsigned int crypto_lock_rand = 0; /* may be set only when a thread
148 * holds CRYPTO_LOCK_RAND (to
149 * prevent double locking) */
150 /* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */
151 /* valid iff crypto_lock_rand is set */
152 static CRYPTO_THREADID locking_threadid;
155 int rand_predictable = 0;
158 const char RAND_version[] = "RAND" OPENSSL_VERSION_PTEXT;
160 static void ssleay_rand_cleanup(void);
161 static void ssleay_rand_seed(const void *buf, int num);
162 static void ssleay_rand_add(const void *buf, int num, double add_entropy);
163 static int ssleay_rand_nopseudo_bytes(unsigned char *buf, int num);
164 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num);
165 static int ssleay_rand_status(void);
167 RAND_METHOD rand_ssleay_meth = {
169 ssleay_rand_nopseudo_bytes,
172 ssleay_rand_pseudo_bytes,
176 RAND_METHOD *RAND_SSLeay(void)
178 return (&rand_ssleay_meth);
181 static void ssleay_rand_cleanup(void)
183 OPENSSL_cleanse(state, sizeof(state));
186 OPENSSL_cleanse(md, MD_DIGEST_LENGTH);
193 static void ssleay_rand_add(const void *buf, int num, double add)
197 unsigned char local_md[MD_DIGEST_LENGTH];
205 * (Based on the rand(3) manpage)
207 * The input is chopped up into units of 20 bytes (or less for
208 * the last block). Each of these blocks is run through the hash
209 * function as follows: The data passed to the hash function
210 * is the current 'md', the same number of bytes from the 'state'
211 * (the location determined by in incremented looping index) as
212 * the current 'block', the new key data 'block', and 'count'
213 * (which is incremented after each use).
214 * The result of this is kept in 'md' and also xored into the
215 * 'state' at the same locations that were used as input into the
219 /* check if we already have the lock */
220 if (crypto_lock_rand) {
222 CRYPTO_THREADID_current(&cur);
223 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
224 do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
225 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
230 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
231 st_idx = state_index;
234 * use our own copies of the counters so that even if a concurrent thread
235 * seeds with exactly the same data and uses the same subarray there's
238 md_c[0] = md_count[0];
239 md_c[1] = md_count[1];
241 memcpy(local_md, md, sizeof md);
243 /* state_index <= state_num <= STATE_SIZE */
245 if (state_index >= STATE_SIZE) {
246 state_index %= STATE_SIZE;
247 state_num = STATE_SIZE;
248 } else if (state_num < STATE_SIZE) {
249 if (state_index > state_num)
250 state_num = state_index;
252 /* state_index <= state_num <= STATE_SIZE */
255 * state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE] are what we
256 * will use now, but other threads may use them as well
259 md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
262 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
265 for (i = 0; i < num; i += MD_DIGEST_LENGTH) {
267 j = (j > MD_DIGEST_LENGTH) ? MD_DIGEST_LENGTH : j;
270 !MD_Update(&m, local_md, MD_DIGEST_LENGTH))
272 k = (st_idx + j) - STATE_SIZE;
274 if (!MD_Update(&m, &(state[st_idx]), j - k) ||
275 !MD_Update(&m, &(state[0]), k))
278 if (!MD_Update(&m, &(state[st_idx]), j))
281 /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
282 if (!MD_Update(&m, buf, j))
285 * We know that line may cause programs such as purify and valgrind
286 * to complain about use of uninitialized data. The problem is not,
287 * it's with the caller. Removing that line will make sure you get
288 * really bad randomness and thereby other problems such as very
292 if (!MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c)) ||
293 !MD_Final(&m, local_md))
297 buf = (const char *)buf + j;
299 for (k = 0; k < j; k++) {
301 * Parallel threads may interfere with this, but always each byte
302 * of the new state is the XOR of some previous value of its and
303 * local_md (itermediate values may be lost). Alway using locking
304 * could hurt performance more than necessary given that
305 * conflicts occur only when the total seeding is longer than the
308 state[st_idx++] ^= local_md[k];
309 if (st_idx >= STATE_SIZE)
315 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
317 * Don't just copy back local_md into md -- this could mean that other
318 * thread's seeding remains without effect (except for the incremented
319 * counter). By XORing it we keep at least as much entropy as fits into
322 for (k = 0; k < (int)sizeof(md); k++) {
323 md[k] ^= local_md[k];
325 if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
328 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
330 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
331 assert(md_c[1] == md_count[1]);
335 EVP_MD_CTX_cleanup(&m);
338 static void ssleay_rand_seed(const void *buf, int num)
340 ssleay_rand_add(buf, num, (double)num);
343 int ssleay_rand_bytes(unsigned char *buf, int num, int pseudo, int lock)
345 static volatile int stirred_pool = 0;
347 size_t num_ceil, st_idx, st_num;
350 unsigned char local_md[MD_DIGEST_LENGTH];
352 #ifndef GETPID_IS_MEANINGLESS
353 pid_t curr_pid = getpid();
355 int do_stir_pool = 0;
358 if (rand_predictable) {
359 static unsigned char val = 0;
361 for (i = 0; i < num; i++)
371 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
373 (1 + (num - 1) / (MD_DIGEST_LENGTH / 2)) * (MD_DIGEST_LENGTH / 2);
376 * (Based on the rand(3) manpage:)
378 * For each group of 10 bytes (or less), we do the following:
380 * Input into the hash function the local 'md' (which is initialized from
381 * the global 'md' before any bytes are generated), the bytes that are to
382 * be overwritten by the random bytes, and bytes from the 'state'
383 * (incrementing looping index). From this digest output (which is kept
384 * in 'md'), the top (up to) 10 bytes are returned to the caller and the
385 * bottom 10 bytes are xored into the 'state'.
387 * Finally, after we have finished 'num' random bytes for the
388 * caller, 'count' (which is incremented) and the local and global 'md'
389 * are fed into the hash function and the results are kept in the
393 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
395 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
396 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
397 CRYPTO_THREADID_current(&locking_threadid);
398 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
399 crypto_lock_rand = 1;
409 ok = (entropy >= ENTROPY_NEEDED);
412 * If the PRNG state is not yet unpredictable, then seeing the PRNG
413 * output may help attackers to determine the new state; thus we have
414 * to decrease the entropy estimate. Once we've had enough initial
415 * seeding we don't bother to adjust the entropy count, though,
416 * because we're not ambitious to provide *information-theoretic*
417 * randomness. NOTE: This approach fails if the program forks before
418 * we have enough entropy. Entropy should be collected in a separate
419 * input pool and be transferred to the output pool only when the
420 * entropy limit has been reached.
429 * In the output function only half of 'md' remains secret, so we
430 * better make sure that the required entropy gets 'evenly
431 * distributed' through 'state', our randomness pool. The input
432 * function (ssleay_rand_add) chains all of 'md', which makes it more
433 * suitable for this purpose.
436 int n = STATE_SIZE; /* so that the complete pool gets accessed */
438 #if MD_DIGEST_LENGTH > 20
439 # error "Please adjust DUMMY_SEED."
441 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
443 * Note that the seed does not matter, it's just that
444 * ssleay_rand_add expects to have something to hash.
446 ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
447 n -= MD_DIGEST_LENGTH;
453 st_idx = state_index;
455 md_c[0] = md_count[0];
456 md_c[1] = md_count[1];
457 memcpy(local_md, md, sizeof md);
459 state_index += num_ceil;
460 if (state_index > state_num)
461 state_index %= state_num;
464 * state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num] are now
465 * ours (but other threads may use them too)
470 /* before unlocking, we must clear 'crypto_lock_rand' */
471 crypto_lock_rand = 0;
473 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
476 /* num_ceil -= MD_DIGEST_LENGTH/2 */
477 j = (num >= MD_DIGEST_LENGTH / 2) ? MD_DIGEST_LENGTH / 2 : num;
481 #ifndef GETPID_IS_MEANINGLESS
482 if (curr_pid) { /* just in the first iteration to save time */
483 if (!MD_Update(&m, (unsigned char *)&curr_pid, sizeof curr_pid))
488 if (!MD_Update(&m, local_md, MD_DIGEST_LENGTH) ||
489 !MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c)))
492 #ifndef PURIFY /* purify complains */
494 * The following line uses the supplied buffer as a small source of
495 * entropy: since this buffer is often uninitialised it may cause
496 * programs such as purify or valgrind to complain. So for those
497 * builds it is not used: the removal of such a small source of
498 * entropy has negligible impact on security.
500 if (!MD_Update(&m, buf, j))
504 k = (st_idx + MD_DIGEST_LENGTH / 2) - st_num;
506 if (!MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2 - k) ||
507 !MD_Update(&m, &(state[0]), k))
510 if (!MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2))
513 if (!MD_Final(&m, local_md))
516 for (i = 0; i < MD_DIGEST_LENGTH / 2; i++) {
517 /* may compete with other threads */
518 state[st_idx++] ^= local_md[i];
519 if (st_idx >= st_num)
522 *(buf++) = local_md[i + MD_DIGEST_LENGTH / 2];
527 !MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c)) ||
528 !MD_Update(&m, local_md, MD_DIGEST_LENGTH))
531 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
532 if (!MD_Update(&m, md, MD_DIGEST_LENGTH) ||
535 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
539 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
541 EVP_MD_CTX_cleanup(&m);
547 RANDerr(RAND_F_SSLEAY_RAND_BYTES, RAND_R_PRNG_NOT_SEEDED);
548 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
549 "http://www.openssl.org/support/faq.html");
554 EVP_MD_CTX_cleanup(&m);
558 static int ssleay_rand_nopseudo_bytes(unsigned char *buf, int num)
560 return ssleay_rand_bytes(buf, num, 0, 1);
564 * pseudo-random bytes that are guaranteed to be unique but not unpredictable
566 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
568 return ssleay_rand_bytes(buf, num, 1, 1);
571 static int ssleay_rand_status(void)
577 CRYPTO_THREADID_current(&cur);
579 * check if we already have the lock (could happen if a RAND_poll()
580 * implementation calls RAND_status())
582 if (crypto_lock_rand) {
583 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
584 do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
585 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
590 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
593 * prevent ssleay_rand_bytes() from trying to obtain the lock again
595 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
596 CRYPTO_THREADID_cpy(&locking_threadid, &cur);
597 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
598 crypto_lock_rand = 1;
606 ret = entropy >= ENTROPY_NEEDED;
609 /* before unlocking, we must clear 'crypto_lock_rand' */
610 crypto_lock_rand = 0;
612 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);