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).
124 #include <openssl/rand.h>
125 #include "rand_lcl.h"
127 #include <openssl/crypto.h>
128 #include <openssl/err.h>
130 # include <openssl/fips.h>
137 /* #define PREDICT 1 */
139 #define STATE_SIZE 1023
140 static int state_num = 0, state_index = 0;
141 static unsigned char state[STATE_SIZE + MD_DIGEST_LENGTH];
142 static unsigned char md[MD_DIGEST_LENGTH];
143 static long md_count[2] = { 0, 0 };
145 static double entropy = 0;
146 static int initialized = 0;
148 static unsigned int crypto_lock_rand = 0; /* may be set only when a thread
149 * holds CRYPTO_LOCK_RAND (to
150 * prevent double locking) */
151 /* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */
152 /* valid iff crypto_lock_rand is set */
153 static unsigned long locking_thread = 0;
156 int rand_predictable = 0;
159 const char RAND_version[] = "RAND" OPENSSL_VERSION_PTEXT;
161 static void ssleay_rand_cleanup(void);
162 static void ssleay_rand_seed(const void *buf, int num);
163 static void ssleay_rand_add(const void *buf, int num, double add_entropy);
164 static int ssleay_rand_bytes(unsigned char *buf, int num);
165 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num);
166 static int ssleay_rand_status(void);
168 RAND_METHOD rand_ssleay_meth = {
173 ssleay_rand_pseudo_bytes,
177 RAND_METHOD *RAND_SSLeay(void)
179 return (&rand_ssleay_meth);
182 static void ssleay_rand_cleanup(void)
184 OPENSSL_cleanse(state, sizeof(state));
187 OPENSSL_cleanse(md, MD_DIGEST_LENGTH);
194 static void ssleay_rand_add(const void *buf, int num, double add)
198 unsigned char local_md[MD_DIGEST_LENGTH];
206 * (Based on the rand(3) manpage)
208 * The input is chopped up into units of 20 bytes (or less for
209 * the last block). Each of these blocks is run through the hash
210 * function as follows: The data passed to the hash function
211 * is the current 'md', the same number of bytes from the 'state'
212 * (the location determined by in incremented looping index) as
213 * the current 'block', the new key data 'block', and 'count'
214 * (which is incremented after each use).
215 * The result of this is kept in 'md' and also xored into the
216 * 'state' at the same locations that were used as input into the
220 /* check if we already have the lock */
221 if (crypto_lock_rand) {
222 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
223 do_not_lock = (locking_thread == CRYPTO_thread_id());
224 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
229 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
230 st_idx = state_index;
233 * use our own copies of the counters so that even if a concurrent thread
234 * seeds with exactly the same data and uses the same subarray there's
237 md_c[0] = md_count[0];
238 md_c[1] = md_count[1];
240 memcpy(local_md, md, sizeof md);
242 /* state_index <= state_num <= STATE_SIZE */
244 if (state_index >= STATE_SIZE) {
245 state_index %= STATE_SIZE;
246 state_num = STATE_SIZE;
247 } else if (state_num < STATE_SIZE) {
248 if (state_index > state_num)
249 state_num = state_index;
251 /* state_index <= state_num <= STATE_SIZE */
254 * state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE] are what we
255 * will use now, but other threads may use them as well
258 md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
261 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
264 for (i = 0; i < num; i += MD_DIGEST_LENGTH) {
266 j = (j > MD_DIGEST_LENGTH) ? MD_DIGEST_LENGTH : j;
269 MD_Update(&m, local_md, MD_DIGEST_LENGTH);
270 k = (st_idx + j) - STATE_SIZE;
272 MD_Update(&m, &(state[st_idx]), j - k);
273 MD_Update(&m, &(state[0]), k);
275 MD_Update(&m, &(state[st_idx]), j);
277 MD_Update(&m, buf, j);
278 MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c));
279 MD_Final(&m, local_md);
282 buf = (const char *)buf + j;
284 for (k = 0; k < j; k++) {
286 * Parallel threads may interfere with this, but always each byte
287 * of the new state is the XOR of some previous value of its and
288 * local_md (itermediate values may be lost). Alway using locking
289 * could hurt performance more than necessary given that
290 * conflicts occur only when the total seeding is longer than the
293 state[st_idx++] ^= local_md[k];
294 if (st_idx >= STATE_SIZE)
298 EVP_MD_CTX_cleanup(&m);
301 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
303 * Don't just copy back local_md into md -- this could mean that other
304 * thread's seeding remains without effect (except for the incremented
305 * counter). By XORing it we keep at least as much entropy as fits into
308 for (k = 0; k < (int)sizeof(md); k++) {
309 md[k] ^= local_md[k];
311 if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
314 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
316 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
317 assert(md_c[1] == md_count[1]);
321 static void ssleay_rand_seed(const void *buf, int num)
323 ssleay_rand_add(buf, num, (double)num);
326 static int ssleay_rand_bytes(unsigned char *buf, int num)
328 static volatile int stirred_pool = 0;
329 int i, j, k, st_num, st_idx;
333 unsigned char local_md[MD_DIGEST_LENGTH];
335 #ifndef GETPID_IS_MEANINGLESS
336 pid_t curr_pid = getpid();
338 int do_stir_pool = 0;
342 FIPSerr(FIPS_F_SSLEAY_RAND_BYTES, FIPS_R_NON_FIPS_METHOD);
348 if (rand_predictable) {
349 static unsigned char val = 0;
351 for (i = 0; i < num; i++)
361 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
363 (1 + (num - 1) / (MD_DIGEST_LENGTH / 2)) * (MD_DIGEST_LENGTH / 2);
366 * (Based on the rand(3) manpage:)
368 * For each group of 10 bytes (or less), we do the following:
370 * Input into the hash function the local 'md' (which is initialized from
371 * the global 'md' before any bytes are generated), the bytes that are to
372 * be overwritten by the random bytes, and bytes from the 'state'
373 * (incrementing looping index). From this digest output (which is kept
374 * in 'md'), the top (up to) 10 bytes are returned to the caller and the
375 * bottom 10 bytes are xored into the 'state'.
377 * Finally, after we have finished 'num' random bytes for the
378 * caller, 'count' (which is incremented) and the local and global 'md'
379 * are fed into the hash function and the results are kept in the
383 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
385 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
386 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
387 locking_thread = CRYPTO_thread_id();
388 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
389 crypto_lock_rand = 1;
399 ok = (entropy >= ENTROPY_NEEDED);
402 * If the PRNG state is not yet unpredictable, then seeing the PRNG
403 * output may help attackers to determine the new state; thus we have
404 * to decrease the entropy estimate. Once we've had enough initial
405 * seeding we don't bother to adjust the entropy count, though,
406 * because we're not ambitious to provide *information-theoretic*
407 * randomness. NOTE: This approach fails if the program forks before
408 * we have enough entropy. Entropy should be collected in a separate
409 * input pool and be transferred to the output pool only when the
410 * entropy limit has been reached.
419 * In the output function only half of 'md' remains secret, so we
420 * better make sure that the required entropy gets 'evenly
421 * distributed' through 'state', our randomness pool. The input
422 * function (ssleay_rand_add) chains all of 'md', which makes it more
423 * suitable for this purpose.
426 int n = STATE_SIZE; /* so that the complete pool gets accessed */
428 #if MD_DIGEST_LENGTH > 20
429 # error "Please adjust DUMMY_SEED."
431 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
433 * Note that the seed does not matter, it's just that
434 * ssleay_rand_add expects to have something to hash.
436 ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
437 n -= MD_DIGEST_LENGTH;
443 st_idx = state_index;
445 md_c[0] = md_count[0];
446 md_c[1] = md_count[1];
447 memcpy(local_md, md, sizeof md);
449 state_index += num_ceil;
450 if (state_index > state_num)
451 state_index %= state_num;
454 * state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num] are now
455 * ours (but other threads may use them too)
460 /* before unlocking, we must clear 'crypto_lock_rand' */
461 crypto_lock_rand = 0;
462 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
465 /* num_ceil -= MD_DIGEST_LENGTH/2 */
466 j = (num >= MD_DIGEST_LENGTH / 2) ? MD_DIGEST_LENGTH / 2 : num;
469 #ifndef GETPID_IS_MEANINGLESS
470 if (curr_pid) { /* just in the first iteration to save time */
471 MD_Update(&m, (unsigned char *)&curr_pid, sizeof curr_pid);
475 MD_Update(&m, local_md, MD_DIGEST_LENGTH);
476 MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c));
478 MD_Update(&m, buf, j); /* purify complains */
480 k = (st_idx + MD_DIGEST_LENGTH / 2) - st_num;
482 MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2 - k);
483 MD_Update(&m, &(state[0]), k);
485 MD_Update(&m, &(state[st_idx]), MD_DIGEST_LENGTH / 2);
486 MD_Final(&m, local_md);
488 for (i = 0; i < MD_DIGEST_LENGTH / 2; i++) {
489 /* may compete with other threads */
490 state[st_idx++] ^= local_md[i];
491 if (st_idx >= st_num)
494 *(buf++) = local_md[i + MD_DIGEST_LENGTH / 2];
499 MD_Update(&m, (unsigned char *)&(md_c[0]), sizeof(md_c));
500 MD_Update(&m, local_md, MD_DIGEST_LENGTH);
501 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
502 MD_Update(&m, md, MD_DIGEST_LENGTH);
504 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
506 EVP_MD_CTX_cleanup(&m);
510 RANDerr(RAND_F_SSLEAY_RAND_BYTES, RAND_R_PRNG_NOT_SEEDED);
511 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
512 "http://www.openssl.org/support/faq.html");
518 * pseudo-random bytes that are guaranteed to be unique but not unpredictable
520 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
525 ret = RAND_bytes(buf, num);
527 err = ERR_peek_error();
528 if (ERR_GET_LIB(err) == ERR_LIB_RAND &&
529 ERR_GET_REASON(err) == RAND_R_PRNG_NOT_SEEDED)
535 static int ssleay_rand_status(void)
541 * check if we already have the lock (could happen if a RAND_poll()
542 * implementation calls RAND_status())
544 if (crypto_lock_rand) {
545 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
546 do_not_lock = (locking_thread == CRYPTO_thread_id());
547 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
552 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
555 * prevent ssleay_rand_bytes() from trying to obtain the lock again
557 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
558 locking_thread = CRYPTO_thread_id();
559 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
560 crypto_lock_rand = 1;
568 ret = entropy >= ENTROPY_NEEDED;
571 /* before unlocking, we must clear 'crypto_lock_rand' */
572 crypto_lock_rand = 0;
574 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);