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>
134 /* #define PREDICT 1 */
136 #define STATE_SIZE 1023
137 static int state_num=0,state_index=0;
138 static unsigned char state[STATE_SIZE+MD_DIGEST_LENGTH];
139 static unsigned char md[MD_DIGEST_LENGTH];
140 static long md_count[2]={0,0};
141 static double entropy=0;
142 static int initialized=0;
144 static unsigned int crypto_lock_rand = 0; /* may be set only when a thread
145 * holds CRYPTO_LOCK_RAND
146 * (to prevent double locking) */
147 /* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */
148 static CRYPTO_THREADID locking_threadid; /* valid iff crypto_lock_rand is set */
152 int rand_predictable=0;
155 const char RAND_version[]="RAND" OPENSSL_VERSION_PTEXT;
157 static void ssleay_rand_cleanup(void);
158 static int ssleay_rand_seed(const void *buf, int num);
159 static int ssleay_rand_add(const void *buf, int num, double add_entropy);
160 static int ssleay_rand_bytes(unsigned char *buf, int num);
161 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num);
162 static int ssleay_rand_status(void);
164 RAND_METHOD rand_ssleay_meth={
169 ssleay_rand_pseudo_bytes,
173 RAND_METHOD *RAND_SSLeay(void)
175 return(&rand_ssleay_meth);
178 static void ssleay_rand_cleanup(void)
180 OPENSSL_cleanse(state,sizeof(state));
183 OPENSSL_cleanse(md,MD_DIGEST_LENGTH);
190 static int ssleay_rand_add(const void *buf, int num, double add)
194 unsigned char local_md[MD_DIGEST_LENGTH];
200 * (Based on the rand(3) manpage)
202 * The input is chopped up into units of 20 bytes (or less for
203 * the last block). Each of these blocks is run through the hash
204 * function as follows: The data passed to the hash function
205 * is the current 'md', the same number of bytes from the 'state'
206 * (the location determined by in incremented looping index) as
207 * the current 'block', the new key data 'block', and 'count'
208 * (which is incremented after each use).
209 * The result of this is kept in 'md' and also xored into the
210 * 'state' at the same locations that were used as input into the
215 /* check if we already have the lock */
216 if (crypto_lock_rand)
219 CRYPTO_THREADID_current(&cur);
220 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
221 do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
222 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
227 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
230 /* use our own copies of the counters so that even
231 * if a concurrent thread seeds with exactly the
232 * same data and uses the same subarray there's _some_
234 md_c[0] = md_count[0];
235 md_c[1] = md_count[1];
237 memcpy(local_md, md, sizeof md);
239 /* state_index <= state_num <= STATE_SIZE */
241 if (state_index >= STATE_SIZE)
243 state_index%=STATE_SIZE;
244 state_num=STATE_SIZE;
246 else if (state_num < STATE_SIZE)
248 if (state_index > state_num)
249 state_num=state_index;
251 /* state_index <= state_num <= STATE_SIZE */
253 /* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE]
254 * are what we will use now, but other threads may use them
257 md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
259 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
261 for (i=0; i<num; i+=MD_DIGEST_LENGTH)
264 j=(j > MD_DIGEST_LENGTH)?MD_DIGEST_LENGTH:j;
268 if (!MD_Update(&m,local_md,MD_DIGEST_LENGTH))
270 k=(st_idx+j)-STATE_SIZE;
273 if (!MD_Update(&m,&(state[st_idx]),j-k))
275 if (!MD_Update(&m,&(state[0]),k))
279 if (!MD_Update(&m,&(state[st_idx]),j))
282 /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
283 if (!MD_Update(&m,buf,j))
285 /* We know that line may cause programs such as
286 purify and valgrind to complain about use of
287 uninitialized data. The problem is not, it's
288 with the caller. Removing that line will make
289 sure you get really bad randomness and thereby
290 other problems such as very insecure keys. */
292 if (!MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c)))
294 if (!MD_Final(&m,local_md))
298 buf=(const char *)buf + j;
302 /* Parallel threads may interfere with this,
303 * but always each byte of the new state is
304 * the XOR of some previous value of its
305 * and local_md (itermediate values may be lost).
306 * Alway using locking could hurt performance more
307 * than necessary given that conflicts occur only
308 * when the total seeding is longer than the random
310 state[st_idx++]^=local_md[k];
311 if (st_idx >= STATE_SIZE)
316 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
317 /* Don't just copy back local_md into md -- this could mean that
318 * other thread's seeding remains without effect (except for
319 * the incremented counter). By XORing it we keep at least as
320 * much entropy as fits into md. */
321 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 */
327 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
329 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
330 assert(md_c[1] == md_count[1]);
334 EVP_MD_CTX_cleanup(&m);
338 static int ssleay_rand_seed(const void *buf, int num)
340 return ssleay_rand_add(buf, num, (double)num);
343 static int ssleay_rand_bytes(unsigned char *buf, int num)
345 static volatile int stirred_pool = 0;
346 int i,j,k,st_num,st_idx;
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)
360 static unsigned char val=0;
362 for (i=0; i<num; i++)
372 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
373 num_ceil = (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;
410 ok = (entropy >= ENTROPY_NEEDED);
413 /* If the PRNG state is not yet unpredictable, then seeing
414 * the PRNG output may help attackers to determine the new
415 * state; thus we have to decrease the entropy estimate.
416 * Once we've had enough initial seeding we don't bother to
417 * adjust the entropy count, though, because we're not ambitious
418 * to provide *information-theoretic* randomness.
420 * NOTE: This approach fails if the program forks before
421 * we have enough entropy. Entropy should be collected
422 * in a separate input pool and be transferred to the
423 * output pool only when the entropy limit has been reached.
432 /* In the output function only half of 'md' remains secret,
433 * so we better make sure that the required entropy gets
434 * 'evenly distributed' through 'state', our randomness pool.
435 * The input function (ssleay_rand_add) chains all of 'md',
436 * which makes it more suitable for this purpose.
439 int n = STATE_SIZE; /* so that the complete pool gets accessed */
442 #if MD_DIGEST_LENGTH > 20
443 # error "Please adjust DUMMY_SEED."
445 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
446 /* Note that the seed does not matter, it's just that
447 * ssleay_rand_add expects to have something to hash. */
448 ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
449 n -= MD_DIGEST_LENGTH;
457 md_c[0] = md_count[0];
458 md_c[1] = md_count[1];
459 memcpy(local_md, md, sizeof md);
461 state_index+=num_ceil;
462 if (state_index > state_num)
463 state_index %= state_num;
465 /* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num]
466 * are now ours (but other threads may use them too) */
470 /* before unlocking, we must clear 'crypto_lock_rand' */
471 crypto_lock_rand = 0;
472 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 */
484 if (!MD_Update(&m,(unsigned char*)&curr_pid,sizeof curr_pid))
489 if (!MD_Update(&m,local_md,MD_DIGEST_LENGTH))
491 if (!MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c)))
494 #ifndef PURIFY /* purify complains */
495 /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
496 if (!MD_Update(&m,buf,j))
498 /* We know that line may cause programs such as
499 purify and valgrind to complain about use of
500 uninitialized data. */
503 k=(st_idx+MD_DIGEST_LENGTH/2)-st_num;
506 if (!MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2-k))
508 if (!MD_Update(&m,&(state[0]),k))
512 if (!MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2))
514 if (!MD_Final(&m,local_md))
517 for (i=0; i<MD_DIGEST_LENGTH/2; i++)
519 state[st_idx++]^=local_md[i]; /* may compete with other threads */
520 if (st_idx >= st_num)
523 *(buf++)=local_md[i+MD_DIGEST_LENGTH/2];
528 || !MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c))
529 || !MD_Update(&m,local_md,MD_DIGEST_LENGTH))
531 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
532 if (!MD_Update(&m,md,MD_DIGEST_LENGTH) || !MD_Final(&m,md))
534 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
537 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
539 EVP_MD_CTX_cleanup(&m);
544 RANDerr(RAND_F_SSLEAY_RAND_BYTES,RAND_R_PRNG_NOT_SEEDED);
545 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
546 "http://www.openssl.org/support/faq.html");
550 EVP_MD_CTX_cleanup(&m);
551 RANDerr(RAND_F_SSLEAY_RAND_BYTES,ERR_R_EVP_LIB);
556 /* pseudo-random bytes that are guaranteed to be unique but not
558 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
563 ret = RAND_bytes(buf, num);
566 err = ERR_peek_error();
567 if (ERR_GET_LIB(err) == ERR_LIB_RAND &&
568 ERR_GET_REASON(err) == RAND_R_PRNG_NOT_SEEDED)
574 static int ssleay_rand_status(void)
580 CRYPTO_THREADID_current(&cur);
581 /* check if we already have the lock
582 * (could happen if a RAND_poll() implementation calls RAND_status()) */
583 if (crypto_lock_rand)
585 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
586 do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
587 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
594 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
596 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
597 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
598 CRYPTO_THREADID_cpy(&locking_threadid, &cur);
599 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
600 crypto_lock_rand = 1;
609 ret = entropy >= ENTROPY_NEEDED;
613 /* before unlocking, we must clear 'crypto_lock_rand' */
614 crypto_lock_rand = 0;
616 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);