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 void ssleay_rand_seed(const void *buf, int num);
159 static void 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 void ssleay_rand_add(const void *buf, int num, double add)
194 unsigned char local_md[MD_DIGEST_LENGTH];
199 * (Based on the rand(3) manpage)
201 * The input is chopped up into units of 20 bytes (or less for
202 * the last block). Each of these blocks is run through the hash
203 * function as follows: The data passed to the hash function
204 * is the current 'md', the same number of bytes from the 'state'
205 * (the location determined by in incremented looping index) as
206 * the current 'block', the new key data 'block', and 'count'
207 * (which is incremented after each use).
208 * The result of this is kept in 'md' and also xored into the
209 * 'state' at the same locations that were used as input into the
213 /* check if we already have the lock */
214 if (crypto_lock_rand)
217 CRYPTO_THREADID_current(&cur);
218 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
219 do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
220 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
225 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
228 /* use our own copies of the counters so that even
229 * if a concurrent thread seeds with exactly the
230 * same data and uses the same subarray there's _some_
232 md_c[0] = md_count[0];
233 md_c[1] = md_count[1];
235 memcpy(local_md, md, sizeof md);
237 /* state_index <= state_num <= STATE_SIZE */
239 if (state_index >= STATE_SIZE)
241 state_index%=STATE_SIZE;
242 state_num=STATE_SIZE;
244 else if (state_num < STATE_SIZE)
246 if (state_index > state_num)
247 state_num=state_index;
249 /* state_index <= state_num <= STATE_SIZE */
251 /* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE]
252 * are what we will use now, but other threads may use them
255 md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
257 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
260 for (i=0; i<num; i+=MD_DIGEST_LENGTH)
263 j=(j > MD_DIGEST_LENGTH)?MD_DIGEST_LENGTH:j;
266 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
267 k=(st_idx+j)-STATE_SIZE;
270 MD_Update(&m,&(state[st_idx]),j-k);
271 MD_Update(&m,&(state[0]),k);
274 MD_Update(&m,&(state[st_idx]),j);
276 /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
278 /* We know that line may cause programs such as
279 purify and valgrind to complain about use of
280 uninitialized data. The problem is not, it's
281 with the caller. Removing that line will make
282 sure you get really bad randomness and thereby
283 other problems such as very insecure keys. */
285 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
286 MD_Final(&m,local_md);
289 buf=(const char *)buf + j;
293 /* Parallel threads may interfere with this,
294 * but always each byte of the new state is
295 * the XOR of some previous value of its
296 * and local_md (itermediate values may be lost).
297 * Alway using locking could hurt performance more
298 * than necessary given that conflicts occur only
299 * when the total seeding is longer than the random
301 state[st_idx++]^=local_md[k];
302 if (st_idx >= STATE_SIZE)
306 EVP_MD_CTX_cleanup(&m);
308 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
309 /* Don't just copy back local_md into md -- this could mean that
310 * other thread's seeding remains without effect (except for
311 * the incremented counter). By XORing it we keep at least as
312 * much entropy as fits into md. */
313 for (k = 0; k < (int)sizeof(md); k++)
315 md[k] ^= local_md[k];
317 if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
319 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
321 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
322 assert(md_c[1] == md_count[1]);
326 static void ssleay_rand_seed(const void *buf, int num)
328 ssleay_rand_add(buf, num, (double)num);
331 static int ssleay_rand_bytes(unsigned char *buf, int num)
333 static volatile int stirred_pool = 0;
334 int i,j,k,st_num,st_idx;
338 unsigned char local_md[MD_DIGEST_LENGTH];
340 #ifndef GETPID_IS_MEANINGLESS
341 pid_t curr_pid = getpid();
343 int do_stir_pool = 0;
346 if (rand_predictable)
348 static unsigned char val=0;
350 for (i=0; i<num; i++)
360 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
361 num_ceil = (1 + (num-1)/(MD_DIGEST_LENGTH/2)) * (MD_DIGEST_LENGTH/2);
364 * (Based on the rand(3) manpage:)
366 * For each group of 10 bytes (or less), we do the following:
368 * Input into the hash function the local 'md' (which is initialized from
369 * the global 'md' before any bytes are generated), the bytes that are to
370 * be overwritten by the random bytes, and bytes from the 'state'
371 * (incrementing looping index). From this digest output (which is kept
372 * in 'md'), the top (up to) 10 bytes are returned to the caller and the
373 * bottom 10 bytes are xored into the 'state'.
375 * Finally, after we have finished 'num' random bytes for the
376 * caller, 'count' (which is incremented) and the local and global 'md'
377 * are fed into the hash function and the results are kept in the
381 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
383 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
384 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
385 CRYPTO_THREADID_current(&locking_threadid);
386 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
387 crypto_lock_rand = 1;
398 ok = (entropy >= ENTROPY_NEEDED);
401 /* If the PRNG state is not yet unpredictable, then seeing
402 * the PRNG output may help attackers to determine the new
403 * state; thus we have to decrease the entropy estimate.
404 * Once we've had enough initial seeding we don't bother to
405 * adjust the entropy count, though, because we're not ambitious
406 * to provide *information-theoretic* randomness.
408 * NOTE: This approach fails if the program forks before
409 * we have enough entropy. Entropy should be collected
410 * in a separate input pool and be transferred to the
411 * output pool only when the entropy limit has been reached.
420 /* In the output function only half of 'md' remains secret,
421 * so we better make sure that the required entropy gets
422 * 'evenly distributed' through 'state', our randomness pool.
423 * The input function (ssleay_rand_add) chains all of 'md',
424 * which makes it more suitable for this purpose.
427 int n = STATE_SIZE; /* so that the complete pool gets accessed */
430 #if MD_DIGEST_LENGTH > 20
431 # error "Please adjust DUMMY_SEED."
433 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
434 /* Note that the seed does not matter, it's just that
435 * 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;
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;
453 /* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num]
454 * are now ours (but other threads may use them too) */
458 /* before unlocking, we must clear 'crypto_lock_rand' */
459 crypto_lock_rand = 0;
460 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
464 /* num_ceil -= MD_DIGEST_LENGTH/2 */
465 j=(num >= MD_DIGEST_LENGTH/2)?MD_DIGEST_LENGTH/2:num;
468 #ifndef GETPID_IS_MEANINGLESS
469 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 #ifndef PURIFY /* purify complains */
479 /* The following line uses the supplied buffer as a small
480 * source of entropy: since this buffer is often uninitialised
481 * it may cause programs such as purify or valgrind to
482 * complain. So for those builds it is not used: the removal
483 * of such a small source of entropy has negligible impact on
489 k=(st_idx+MD_DIGEST_LENGTH/2)-st_num;
492 MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2-k);
493 MD_Update(&m,&(state[0]),k);
496 MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2);
497 MD_Final(&m,local_md);
499 for (i=0; i<MD_DIGEST_LENGTH/2; i++)
501 state[st_idx++]^=local_md[i]; /* may compete with other threads */
502 if (st_idx >= st_num)
505 *(buf++)=local_md[i+MD_DIGEST_LENGTH/2];
510 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
511 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
512 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
513 MD_Update(&m,md,MD_DIGEST_LENGTH);
515 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
517 EVP_MD_CTX_cleanup(&m);
522 RANDerr(RAND_F_SSLEAY_RAND_BYTES,RAND_R_PRNG_NOT_SEEDED);
523 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
524 "http://www.openssl.org/support/faq.html");
529 /* pseudo-random bytes that are guaranteed to be unique but not
531 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
536 ret = RAND_bytes(buf, num);
539 err = ERR_peek_error();
540 if (ERR_GET_LIB(err) == ERR_LIB_RAND &&
541 ERR_GET_REASON(err) == RAND_R_PRNG_NOT_SEEDED)
547 static int ssleay_rand_status(void)
553 CRYPTO_THREADID_current(&cur);
554 /* check if we already have the lock
555 * (could happen if a RAND_poll() implementation calls RAND_status()) */
556 if (crypto_lock_rand)
558 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
559 do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
560 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
567 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
569 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
570 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
571 CRYPTO_THREADID_cpy(&locking_threadid, &cur);
572 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
573 crypto_lock_rand = 1;
582 ret = entropy >= ENTROPY_NEEDED;
586 /* before unlocking, we must clear 'crypto_lock_rand' */
587 crypto_lock_rand = 0;
589 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);