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, size_t num);
159 static void ssleay_rand_add(const void *buf, size_t num, double add_entropy);
160 static int ssleay_rand_bytes(unsigned char *buf, size_t num);
161 static int ssleay_rand_pseudo_bytes(unsigned char *buf, size_t 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, size_t num, double add)
196 unsigned char local_md[MD_DIGEST_LENGTH];
201 * (Based on the rand(3) manpage)
203 * The input is chopped up into units of 20 bytes (or less for
204 * the last block). Each of these blocks is run through the hash
205 * function as follows: The data passed to the hash function
206 * is the current 'md', the same number of bytes from the 'state'
207 * (the location determined by in incremented looping index) as
208 * the current 'block', the new key data 'block', and 'count'
209 * (which is incremented after each use).
210 * The result of this is kept in 'md' and also xored into the
211 * '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);
262 for (i=0; i<num; i+=MD_DIGEST_LENGTH)
265 j=(j > MD_DIGEST_LENGTH)?MD_DIGEST_LENGTH:j;
268 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
269 k=(st_idx+j)-STATE_SIZE;
272 MD_Update(&m,&(state[st_idx]),j-k);
273 MD_Update(&m,&(state[0]),k);
276 MD_Update(&m,&(state[st_idx]),j);
279 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
280 MD_Final(&m,local_md);
283 buf=(const char *)buf + j;
287 /* Parallel threads may interfere with this,
288 * but always each byte of the new state is
289 * the XOR of some previous value of its
290 * and local_md (itermediate values may be lost).
291 * Alway using locking could hurt performance more
292 * than necessary given that conflicts occur only
293 * when the total seeding is longer than the random
295 state[st_idx++]^=local_md[k];
296 if (st_idx >= STATE_SIZE)
300 EVP_MD_CTX_cleanup(&m);
302 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
303 /* Don't just copy back local_md into md -- this could mean that
304 * other thread's seeding remains without effect (except for
305 * the incremented counter). By XORing it we keep at least as
306 * much entropy as fits into md. */
307 for (k = 0; k < sizeof(md); k++)
309 md[k] ^= local_md[k];
311 if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
313 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
315 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
316 assert(md_c[1] == md_count[1]);
320 static void ssleay_rand_seed(const void *buf, size_t num)
322 ssleay_rand_add(buf, num, (double)num);
325 static int ssleay_rand_bytes(unsigned char *buf, size_t num)
327 static volatile int stirred_pool = 0;
334 unsigned char local_md[MD_DIGEST_LENGTH];
336 #ifndef GETPID_IS_MEANINGLESS
337 pid_t curr_pid = getpid();
339 int do_stir_pool = 0;
342 if (rand_predictable)
344 static unsigned char val=0;
346 for (i=0; i<num; i++)
356 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
357 num_ceil = (1 + (num-1)/(MD_DIGEST_LENGTH/2)) * (MD_DIGEST_LENGTH/2);
360 * (Based on the rand(3) manpage:)
362 * For each group of 10 bytes (or less), we do the following:
364 * Input into the hash function the local 'md' (which is initialized from
365 * the global 'md' before any bytes are generated), the bytes that are to
366 * be overwritten by the random bytes, and bytes from the 'state'
367 * (incrementing looping index). From this digest output (which is kept
368 * in 'md'), the top (up to) 10 bytes are returned to the caller and the
369 * bottom 10 bytes are xored into the 'state'.
371 * Finally, after we have finished 'num' random bytes for the
372 * caller, 'count' (which is incremented) and the local and global 'md'
373 * are fed into the hash function and the results are kept in the
377 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
379 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
380 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
381 CRYPTO_THREADID_current(&locking_threadid);
382 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
383 crypto_lock_rand = 1;
394 ok = (entropy >= ENTROPY_NEEDED);
397 /* If the PRNG state is not yet unpredictable, then seeing
398 * the PRNG output may help attackers to determine the new
399 * state; thus we have to decrease the entropy estimate.
400 * Once we've had enough initial seeding we don't bother to
401 * adjust the entropy count, though, because we're not ambitious
402 * to provide *information-theoretic* randomness.
404 * NOTE: This approach fails if the program forks before
405 * we have enough entropy. Entropy should be collected
406 * in a separate input pool and be transferred to the
407 * output pool only when the entropy limit has been reached.
416 /* In the output function only half of 'md' remains secret,
417 * so we better make sure that the required entropy gets
418 * 'evenly distributed' through 'state', our randomness pool.
419 * The input function (ssleay_rand_add) chains all of 'md',
420 * which makes it more suitable for this purpose.
423 int n = STATE_SIZE; /* so that the complete pool gets accessed */
426 #if MD_DIGEST_LENGTH > 20
427 # error "Please adjust DUMMY_SEED."
429 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
430 /* Note that the seed does not matter, it's just that
431 * ssleay_rand_add expects to have something to hash. */
432 ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
433 n -= MD_DIGEST_LENGTH;
441 md_c[0] = md_count[0];
442 md_c[1] = md_count[1];
443 memcpy(local_md, md, sizeof md);
445 state_index+=num_ceil;
446 if (state_index > state_num)
447 state_index %= state_num;
449 /* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num]
450 * are now ours (but other threads may use them too) */
454 /* before unlocking, we must clear 'crypto_lock_rand' */
455 crypto_lock_rand = 0;
456 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
460 /* num_ceil -= MD_DIGEST_LENGTH/2 */
461 j=(num >= MD_DIGEST_LENGTH/2)?MD_DIGEST_LENGTH/2:num;
464 #ifndef GETPID_IS_MEANINGLESS
465 if (curr_pid) /* just in the first iteration to save time */
467 MD_Update(&m,(unsigned char*)&curr_pid,sizeof curr_pid);
471 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
472 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
474 MD_Update(&m,buf,j); /* purify complains */
476 k=(st_idx+MD_DIGEST_LENGTH/2)-st_num;
479 MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2-k);
480 MD_Update(&m,&(state[0]),k);
483 MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2);
484 MD_Final(&m,local_md);
486 for (i=0; i<MD_DIGEST_LENGTH/2; i++)
488 state[st_idx++]^=local_md[i]; /* may compete with other threads */
489 if (st_idx >= st_num)
492 *(buf++)=local_md[i+MD_DIGEST_LENGTH/2];
497 MD_Update(&m,&(md_c[0]),sizeof(md_c));
498 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
499 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
500 MD_Update(&m,md,MD_DIGEST_LENGTH);
502 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
504 EVP_MD_CTX_cleanup(&m);
509 RANDerr(RAND_F_SSLEAY_RAND_BYTES,RAND_R_PRNG_NOT_SEEDED);
510 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
511 "http://www.openssl.org/support/faq.html");
516 /* pseudo-random bytes that are guaranteed to be unique but not
518 static int ssleay_rand_pseudo_bytes(unsigned char *buf, size_t num)
523 ret = RAND_bytes(buf, num);
526 err = ERR_peek_error();
527 if (ERR_GET_LIB(err) == ERR_LIB_RAND &&
528 ERR_GET_REASON(err) == RAND_R_PRNG_NOT_SEEDED)
534 static int ssleay_rand_status(void)
540 CRYPTO_THREADID_current(&cur);
541 /* check if we already have the lock
542 * (could happen if a RAND_poll() implementation calls RAND_status()) */
543 if (crypto_lock_rand)
545 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
546 do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
547 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
554 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
556 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
557 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
558 CRYPTO_THREADID_cpy(&locking_threadid, &cur);
559 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
560 crypto_lock_rand = 1;
569 ret = entropy >= ENTROPY_NEEDED;
573 /* before unlocking, we must clear 'crypto_lock_rand' */
574 crypto_lock_rand = 0;
576 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);