1 /* crypto/rand/md_rand.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 * All rights reserved.
4 *
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.
8 *
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).
15 *
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.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
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)"
40 *
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
51 * SUCH DAMAGE.
52 *
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.]
57 */
58 /* ====================================================================
59 * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved.
60 *
61 * Redistribution and use in source and binary forms, with or without
62 * modification, are permitted provided that the following conditions
63 * are met:
64 *
65 * 1. Redistributions of source code must retain the above copyright
66 * notice, this list of conditions and the following disclaimer.
67 *
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
71 * distribution.
72 *
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/)"
77 *
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.
82 *
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.
86 *
87 * 6. Redistributions of any form whatsoever must retain the following
88 * acknowledgment:
89 * "This product includes software developed by the OpenSSL Project
90 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
91 *
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 * ====================================================================
105 *
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).
109 *
110 */
111
112 #define OPENSSL_FIPSEVP
113
114 #ifdef MD_RAND_DEBUG
115 # ifndef NDEBUG
116 # define NDEBUG
117 # endif
118 #endif
119
120 #include <assert.h>
121 #include <stdio.h>
122 #include <string.h>
123
124 #include "e_os.h"
125
126 #include <openssl/crypto.h>
127 #include <openssl/rand.h>
128 #include "rand_lcl.h"
129
130 #include <openssl/err.h>
131
132 #ifdef BN_DEBUG
133 # define PREDICT
134 #endif
135
136 /* #define PREDICT 1 */
137
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;
145
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 */
151
152
153 #ifdef PREDICT
154 int rand_predictable=0;
155 #endif
156
157 const char RAND_version[]="RAND" OPENSSL_VERSION_PTEXT;
158
159 static void ssleay_rand_cleanup(void);
160 static void ssleay_rand_seed(const void *buf, int num);
161 static void ssleay_rand_add(const void *buf, int num, double add_entropy);
162 static int ssleay_rand_nopseudo_bytes(unsigned char *buf, int num);
163 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num);
164 static int ssleay_rand_status(void);
165
166 RAND_METHOD rand_ssleay_meth={
167 ssleay_rand_seed,
168 ssleay_rand_nopseudo_bytes,
169 ssleay_rand_cleanup,
170 ssleay_rand_add,
171 ssleay_rand_pseudo_bytes,
172 ssleay_rand_status
173 };
174
175 RAND_METHOD *RAND_SSLeay(void)
176 {
177 return(&rand_ssleay_meth);
178 }
179
180 static void ssleay_rand_cleanup(void)
181 {
182 OPENSSL_cleanse(state,sizeof(state));
183 state_num=0;
184 state_index=0;
185 OPENSSL_cleanse(md,MD_DIGEST_LENGTH);
186 md_count[0]=0;
187 md_count[1]=0;
188 entropy=0;
189 initialized=0;
190 }
191
192 static void ssleay_rand_add(const void *buf, int num, double add)
193 {
194 int i,j,k,st_idx;
195 long md_c[2];
196 unsigned char local_md[MD_DIGEST_LENGTH];
197 EVP_MD_CTX m;
198 int do_not_lock;
199
200 if (!num)
201 return;
202
203 /*
204 * (Based on the rand(3) manpage)
205 *
206 * The input is chopped up into units of 20 bytes (or less for
207 * the last block). Each of these blocks is run through the hash
208 * function as follows: The data passed to the hash function
209 * is the current 'md', the same number of bytes from the 'state'
210 * (the location determined by in incremented looping index) as
211 * the current 'block', the new key data 'block', and 'count'
212 * (which is incremented after each use).
213 * The result of this is kept in 'md' and also xored into the
214 * 'state' at the same locations that were used as input into the
215 * hash function.
216 */
217
218 /* check if we already have the lock */
219 if (crypto_lock_rand)
220 {
221 CRYPTO_THREADID cur;
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);
226 }
227 else
228 do_not_lock = 0;
229
230 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
231 st_idx=state_index;
232
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_
236 * difference */
237 md_c[0] = md_count[0];
238 md_c[1] = md_count[1];
239
240 memcpy(local_md, md, sizeof md);
241
242 /* state_index <= state_num <= STATE_SIZE */
243 state_index += num;
244 if (state_index >= STATE_SIZE)
245 {
246 state_index%=STATE_SIZE;
247 state_num=STATE_SIZE;
248 }
249 else if (state_num < STATE_SIZE)
250 {
251 if (state_index > state_num)
252 state_num=state_index;
253 }
254 /* state_index <= state_num <= STATE_SIZE */
255
256 /* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE]
257 * are what we will use now, but other threads may use them
258 * as well */
259
260 md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
261
262 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
263
264 EVP_MD_CTX_init(&m);
265 for (i=0; i<num; i+=MD_DIGEST_LENGTH)
266 {
267 j=(num-i);
268 j=(j > MD_DIGEST_LENGTH)?MD_DIGEST_LENGTH:j;
269
270 MD_Init(&m);
271 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
272 k=(st_idx+j)-STATE_SIZE;
273 if (k > 0)
274 {
275 MD_Update(&m,&(state[st_idx]),j-k);
276 MD_Update(&m,&(state[0]),k);
277 }
278 else
279 MD_Update(&m,&(state[st_idx]),j);
280
281 /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
282 MD_Update(&m,buf,j);
283 /* We know that line may cause programs such as
284 purify and valgrind to complain about use of
285 uninitialized data. The problem is not, it's
286 with the caller. Removing that line will make
287 sure you get really bad randomness and thereby
288 other problems such as very insecure keys. */
289
290 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
291 MD_Final(&m,local_md);
292 md_c[1]++;
293
294 buf=(const char *)buf + j;
295
296 for (k=0; k<j; k++)
297 {
298 /* Parallel threads may interfere with this,
299 * but always each byte of the new state is
300 * the XOR of some previous value of its
301 * and local_md (itermediate values may be lost).
302 * Alway using locking could hurt performance more
303 * than necessary given that conflicts occur only
304 * when the total seeding is longer than the random
305 * state. */
306 state[st_idx++]^=local_md[k];
307 if (st_idx >= STATE_SIZE)
308 st_idx=0;
309 }
310 }
311 EVP_MD_CTX_cleanup(&m);
312
313 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
314 /* Don't just copy back local_md into md -- this could mean that
315 * other thread's seeding remains without effect (except for
316 * the incremented counter). By XORing it we keep at least as
317 * much entropy as fits into md. */
318 for (k = 0; k < (int)sizeof(md); k++)
319 {
320 md[k] ^= local_md[k];
321 }
322 if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
323 entropy += add;
324 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
325
326 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
327 assert(md_c[1] == md_count[1]);
328 #endif
329 }
330
331 static void ssleay_rand_seed(const void *buf, int num)
332 {
333 ssleay_rand_add(buf, num, (double)num);
334 }
335
336 int ssleay_rand_bytes(unsigned char *buf, int num, int pseudo, int lock)
337 {
338 static volatile int stirred_pool = 0;
339 int i,j,k,st_num,st_idx;
340 int num_ceil;
341 int ok;
342 long md_c[2];
343 unsigned char local_md[MD_DIGEST_LENGTH];
344 EVP_MD_CTX m;
345 #ifndef GETPID_IS_MEANINGLESS
346 pid_t curr_pid = getpid();
347 #endif
348 int do_stir_pool = 0;
349
350 #ifdef PREDICT
351 if (rand_predictable)
352 {
353 static unsigned char val=0;
354
355 for (i=0; i<num; i++)
356 buf[i]=val++;
357 return(1);
358 }
359 #endif
360
361 if (num <= 0)
362 return 1;
363
364 EVP_MD_CTX_init(&m);
365 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
366 num_ceil = (1 + (num-1)/(MD_DIGEST_LENGTH/2)) * (MD_DIGEST_LENGTH/2);
367
368 /*
369 * (Based on the rand(3) manpage:)
370 *
371 * For each group of 10 bytes (or less), we do the following:
372 *
373 * Input into the hash function the local 'md' (which is initialized from
374 * the global 'md' before any bytes are generated), the bytes that are to
375 * be overwritten by the random bytes, and bytes from the 'state'
376 * (incrementing looping index). From this digest output (which is kept
377 * in 'md'), the top (up to) 10 bytes are returned to the caller and the
378 * bottom 10 bytes are xored into the 'state'.
379 *
380 * Finally, after we have finished 'num' random bytes for the
381 * caller, 'count' (which is incremented) and the local and global 'md'
382 * are fed into the hash function and the results are kept in the
383 * global 'md'.
384 */
385 if (lock)
386 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
387
388 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
389 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
390 CRYPTO_THREADID_current(&locking_threadid);
391 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
392 crypto_lock_rand = 1;
393
394 if (!initialized)
395 {
396 RAND_poll();
397 initialized = 1;
398 }
399
400 if (!stirred_pool)
401 do_stir_pool = 1;
402
403 ok = (entropy >= ENTROPY_NEEDED);
404 if (!ok)
405 {
406 /* If the PRNG state is not yet unpredictable, then seeing
407 * the PRNG output may help attackers to determine the new
408 * state; thus we have to decrease the entropy estimate.
409 * Once we've had enough initial seeding we don't bother to
410 * adjust the entropy count, though, because we're not ambitious
411 * to provide *information-theoretic* randomness.
412 *
413 * NOTE: This approach fails if the program forks before
414 * we have enough entropy. Entropy should be collected
415 * in a separate input pool and be transferred to the
416 * output pool only when the entropy limit has been reached.
417 */
418 entropy -= num;
419 if (entropy < 0)
420 entropy = 0;
421 }
422
423 if (do_stir_pool)
424 {
425 /* In the output function only half of 'md' remains secret,
426 * so we better make sure that the required entropy gets
427 * 'evenly distributed' through 'state', our randomness pool.
428 * The input function (ssleay_rand_add) chains all of 'md',
429 * which makes it more suitable for this purpose.
430 */
431
432 int n = STATE_SIZE; /* so that the complete pool gets accessed */
433 while (n > 0)
434 {
435 #if MD_DIGEST_LENGTH > 20
436 # error "Please adjust DUMMY_SEED."
437 #endif
438 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
439 /* Note that the seed does not matter, it's just that
440 * ssleay_rand_add expects to have something to hash. */
441 ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
442 n -= MD_DIGEST_LENGTH;
443 }
444 if (ok)
445 stirred_pool = 1;
446 }
447
448 st_idx=state_index;
449 st_num=state_num;
450 md_c[0] = md_count[0];
451 md_c[1] = md_count[1];
452 memcpy(local_md, md, sizeof md);
453
454 state_index+=num_ceil;
455 if (state_index > state_num)
456 state_index %= state_num;
457
458 /* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num]
459 * are now ours (but other threads may use them too) */
460
461 md_count[0] += 1;
462
463 /* before unlocking, we must clear 'crypto_lock_rand' */
464 crypto_lock_rand = 0;
465 if (lock)
466 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
467
468 while (num > 0)
469 {
470 /* num_ceil -= MD_DIGEST_LENGTH/2 */
471 j=(num >= MD_DIGEST_LENGTH/2)?MD_DIGEST_LENGTH/2:num;
472 num-=j;
473 MD_Init(&m);
474 #ifndef GETPID_IS_MEANINGLESS
475 if (curr_pid) /* just in the first iteration to save time */
476 {
477 MD_Update(&m,(unsigned char*)&curr_pid,sizeof curr_pid);
478 curr_pid = 0;
479 }
480 #endif
481 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
482 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
483
484 #ifndef PURIFY /* purify complains */
485 /* The following line uses the supplied buffer as a small
486 * source of entropy: since this buffer is often uninitialised
487 * it may cause programs such as purify or valgrind to
488 * complain. So for those builds it is not used: the removal
489 * of such a small source of entropy has negligible impact on
490 * security.
491 */
492 MD_Update(&m,buf,j);
493 #endif
494
495 k=(st_idx+MD_DIGEST_LENGTH/2)-st_num;
496 if (k > 0)
497 {
498 MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2-k);
499 MD_Update(&m,&(state[0]),k);
500 }
501 else
502 MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2);
503 MD_Final(&m,local_md);
504
505 for (i=0; i<MD_DIGEST_LENGTH/2; i++)
506 {
507 state[st_idx++]^=local_md[i]; /* may compete with other threads */
508 if (st_idx >= st_num)
509 st_idx=0;
510 if (i < j)
511 *(buf++)=local_md[i+MD_DIGEST_LENGTH/2];
512 }
513 }
514
515 MD_Init(&m);
516 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
517 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
518 if (lock)
519 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
520 MD_Update(&m,md,MD_DIGEST_LENGTH);
521 MD_Final(&m,md);
522 if (lock)
523 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
524
525 EVP_MD_CTX_cleanup(&m);
526 if (ok)
527 return(1);
528 else if (pseudo)
529 return 0;
530 else
531 {
532 RANDerr(RAND_F_SSLEAY_RAND_BYTES,RAND_R_PRNG_NOT_SEEDED);
533 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
534 "http://www.openssl.org/support/faq.html");
535 return(0);
536 }
537 }
538
539 static int ssleay_rand_nopseudo_bytes(unsigned char *buf, int num)
540 {
541 return ssleay_rand_bytes(buf, num, 0, 1);
542 }
543
544 /* pseudo-random bytes that are guaranteed to be unique but not
545 unpredictable */
546 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
547 {
548 return ssleay_rand_bytes(buf, num, 1, 1);
549 }
550
551 static int ssleay_rand_status(void)
552 {
553 CRYPTO_THREADID cur;
554 int ret;
555 int do_not_lock;
556
557 CRYPTO_THREADID_current(&cur);
558 /* check if we already have the lock
559 * (could happen if a RAND_poll() implementation calls RAND_status()) */
560 if (crypto_lock_rand)
561 {
562 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
563 do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
564 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
565 }
566 else
567 do_not_lock = 0;
568
569 if (!do_not_lock)
570 {
571 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
572
573 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
574 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
575 CRYPTO_THREADID_cpy(&locking_threadid, &cur);
576 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
577 crypto_lock_rand = 1;
578 }
579
580 if (!initialized)
581 {
582 RAND_poll();
583 initialized = 1;
584 }
585
586 ret = entropy >= ENTROPY_NEEDED;
587
588 if (!do_not_lock)
589 {
590 /* before unlocking, we must clear 'crypto_lock_rand' */
591 crypto_lock_rand = 0;
592
593 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
594 }
595
596 return ret;
597 }