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_FIPSAPI
126 #include <openssl/rand.h>
127 #include "rand_lcl.h"
129 #include <openssl/crypto.h>
130 #include <openssl/err.h>
136 /* #define PREDICT 1 */
138 #define STATE_SIZE 1023
139 static int 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};
143 static double entropy=0;
144 static int initialized=0;
146 static unsigned int crypto_lock_rand = 0; /* may be set only when a thread
147 * holds CRYPTO_LOCK_RAND
148 * (to prevent double locking) */
149 /* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */
150 static CRYPTO_THREADID locking_threadid; /* valid iff crypto_lock_rand is set */
154 int rand_predictable=0;
157 const char RAND_version[]="RAND" OPENSSL_VERSION_PTEXT;
159 static void ssleay_rand_cleanup(void);
160 static int ssleay_rand_seed(const void *buf, int num);
161 static int ssleay_rand_add(const void *buf, int num, double add_entropy);
162 static int ssleay_rand_bytes(unsigned char *buf, int num, int pseudo);
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 int ssleay_rand_add(const void *buf, int num, double add)
197 unsigned char local_md[MD_DIGEST_LENGTH];
203 * (Based on the rand(3) manpage)
205 * The input is chopped up into units of 20 bytes (or less for
206 * the last block). Each of these blocks is run through the hash
207 * function as follows: The data passed to the hash function
208 * is the current 'md', the same number of bytes from the 'state'
209 * (the location determined by in incremented looping index) as
210 * the current 'block', the new key data 'block', and 'count'
211 * (which is incremented after each use).
212 * The result of this is kept in 'md' and also xored into the
213 * 'state' at the same locations that were used as input into the
218 /* check if we already have the lock */
219 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 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
233 /* use our own copies of the counters so that even
234 * if a concurrent thread seeds with exactly the
235 * same data and uses the same subarray there's _some_
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)
246 state_index%=STATE_SIZE;
247 state_num=STATE_SIZE;
249 else if (state_num < STATE_SIZE)
251 if (state_index > state_num)
252 state_num=state_index;
254 /* state_index <= state_num <= STATE_SIZE */
256 /* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE]
257 * are what we will use now, but other threads may use them
260 md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
262 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
264 for (i=0; i<num; i+=MD_DIGEST_LENGTH)
267 j=(j > MD_DIGEST_LENGTH)?MD_DIGEST_LENGTH:j;
271 if (!MD_Update(&m,local_md,MD_DIGEST_LENGTH))
273 k=(st_idx+j)-STATE_SIZE;
276 if (!MD_Update(&m,&(state[st_idx]),j-k))
278 if (!MD_Update(&m,&(state[0]),k))
282 if (!MD_Update(&m,&(state[st_idx]),j))
285 /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
286 if (!MD_Update(&m,buf,j))
288 /* We know that line may cause programs such as
289 purify and valgrind to complain about use of
290 uninitialized data. The problem is not, it's
291 with the caller. Removing that line will make
292 sure you get really bad randomness and thereby
293 other problems such as very insecure keys. */
295 if (!MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c)))
297 if (!MD_Final(&m,local_md))
301 buf=(const char *)buf + j;
305 /* Parallel threads may interfere with this,
306 * but always each byte of the new state is
307 * the XOR of some previous value of its
308 * and local_md (itermediate values may be lost).
309 * Alway using locking could hurt performance more
310 * than necessary given that conflicts occur only
311 * when the total seeding is longer than the random
313 state[st_idx++]^=local_md[k];
314 if (st_idx >= STATE_SIZE)
319 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
320 /* Don't just copy back local_md into md -- this could mean that
321 * other thread's seeding remains without effect (except for
322 * the incremented counter). By XORing it we keep at least as
323 * much entropy as fits into md. */
324 for (k = 0; k < (int)sizeof(md); k++)
326 md[k] ^= local_md[k];
328 if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
330 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
332 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
333 assert(md_c[1] == md_count[1]);
337 EVP_MD_CTX_cleanup(&m);
341 static int ssleay_rand_seed(const void *buf, int num)
343 return ssleay_rand_add(buf, num, (double)num);
346 static int ssleay_rand_bytes(unsigned char *buf, int num, int pseudo)
348 static volatile int stirred_pool = 0;
349 int i,j,k,st_num,st_idx;
353 unsigned char local_md[MD_DIGEST_LENGTH];
355 #ifndef GETPID_IS_MEANINGLESS
356 pid_t curr_pid = getpid();
358 int do_stir_pool = 0;
361 if (rand_predictable)
363 static unsigned char val=0;
365 for (i=0; i<num; i++)
375 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
376 num_ceil = (1 + (num-1)/(MD_DIGEST_LENGTH/2)) * (MD_DIGEST_LENGTH/2);
379 * (Based on the rand(3) manpage:)
381 * For each group of 10 bytes (or less), we do the following:
383 * Input into the hash function the local 'md' (which is initialized from
384 * the global 'md' before any bytes are generated), the bytes that are to
385 * be overwritten by the random bytes, and bytes from the 'state'
386 * (incrementing looping index). From this digest output (which is kept
387 * in 'md'), the top (up to) 10 bytes are returned to the caller and the
388 * bottom 10 bytes are xored into the 'state'.
390 * Finally, after we have finished 'num' random bytes for the
391 * caller, 'count' (which is incremented) and the local and global 'md'
392 * are fed into the hash function and the results are kept in the
396 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
398 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
399 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
400 CRYPTO_THREADID_current(&locking_threadid);
401 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
402 crypto_lock_rand = 1;
413 ok = (entropy >= ENTROPY_NEEDED);
416 /* If the PRNG state is not yet unpredictable, then seeing
417 * the PRNG output may help attackers to determine the new
418 * state; thus we have to decrease the entropy estimate.
419 * Once we've had enough initial seeding we don't bother to
420 * adjust the entropy count, though, because we're not ambitious
421 * to provide *information-theoretic* randomness.
423 * NOTE: This approach fails if the program forks before
424 * we have enough entropy. Entropy should be collected
425 * in a separate input pool and be transferred to the
426 * output pool only when the entropy limit has been reached.
435 /* In the output function only half of 'md' remains secret,
436 * so we better make sure that the required entropy gets
437 * 'evenly distributed' through 'state', our randomness pool.
438 * The input function (ssleay_rand_add) chains all of 'md',
439 * which makes it more suitable for this purpose.
442 int n = STATE_SIZE; /* so that the complete pool gets accessed */
445 #if MD_DIGEST_LENGTH > 20
446 # error "Please adjust DUMMY_SEED."
448 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
449 /* Note that the seed does not matter, it's just that
450 * ssleay_rand_add expects to have something to hash. */
451 ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
452 n -= MD_DIGEST_LENGTH;
460 md_c[0] = md_count[0];
461 md_c[1] = md_count[1];
462 memcpy(local_md, md, sizeof md);
464 state_index+=num_ceil;
465 if (state_index > state_num)
466 state_index %= state_num;
468 /* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num]
469 * are now ours (but other threads may use them too) */
473 /* before unlocking, we must clear 'crypto_lock_rand' */
474 crypto_lock_rand = 0;
475 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
479 /* num_ceil -= MD_DIGEST_LENGTH/2 */
480 j=(num >= MD_DIGEST_LENGTH/2)?MD_DIGEST_LENGTH/2:num;
484 #ifndef GETPID_IS_MEANINGLESS
485 if (curr_pid) /* just in the first iteration to save time */
487 if (!MD_Update(&m,(unsigned char*)&curr_pid,sizeof curr_pid))
492 if (!MD_Update(&m,local_md,MD_DIGEST_LENGTH))
494 if (!MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c)))
497 #ifndef PURIFY /* purify complains */
498 /* The following line uses the supplied buffer as a small
499 * source of entropy: since this buffer is often uninitialised
500 * it may cause programs such as purify or valgrind to
501 * complain. So for those builds it is not used: the removal
502 * of such a small source of entropy has negligible impact on
505 if (!MD_Update(&m,buf,j))
509 k=(st_idx+MD_DIGEST_LENGTH/2)-st_num;
512 if (!MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2-k))
514 if (!MD_Update(&m,&(state[0]),k))
518 if (!MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2))
520 if (!MD_Final(&m,local_md))
523 for (i=0; i<MD_DIGEST_LENGTH/2; i++)
525 state[st_idx++]^=local_md[i]; /* may compete with other threads */
526 if (st_idx >= st_num)
529 *(buf++)=local_md[i+MD_DIGEST_LENGTH/2];
534 || !MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c))
535 || !MD_Update(&m,local_md,MD_DIGEST_LENGTH))
537 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
538 if (!MD_Update(&m,md,MD_DIGEST_LENGTH) || !MD_Final(&m,md))
540 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
543 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
545 EVP_MD_CTX_cleanup(&m);
552 RANDerr(RAND_F_SSLEAY_RAND_BYTES,RAND_R_PRNG_NOT_SEEDED);
553 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
554 "http://www.openssl.org/support/faq.html");
558 EVP_MD_CTX_cleanup(&m);
559 RANDerr(RAND_F_SSLEAY_RAND_BYTES,ERR_R_EVP_LIB);
564 static int ssleay_rand_nopseudo_bytes(unsigned char *buf, int num)
566 return ssleay_rand_bytes(buf, num, 0);
569 /* pseudo-random bytes that are guaranteed to be unique but not
571 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
573 return ssleay_rand_bytes(buf, num, 1);
576 static int ssleay_rand_status(void)
582 CRYPTO_THREADID_current(&cur);
583 /* check if we already have the lock
584 * (could happen if a RAND_poll() implementation calls RAND_status()) */
585 if (crypto_lock_rand)
587 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
588 do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
589 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
596 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
598 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
599 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
600 CRYPTO_THREADID_cpy(&locking_threadid, &cur);
601 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
602 crypto_lock_rand = 1;
611 ret = entropy >= ENTROPY_NEEDED;
615 /* before unlocking, we must clear 'crypto_lock_rand' */
616 crypto_lock_rand = 0;
618 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);