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 #ifdef MD_RAND_DEBUG
113 # ifndef NDEBUG
114 # define NDEBUG
115 # endif
116 #endif
117
118 #include <assert.h>
119 #include <stdio.h>
120 #include <string.h>
121
122 #include "e_os.h"
123
124 #include <openssl/rand.h>
125 #include "rand_lcl.h"
126
127 #include <openssl/crypto.h>
128 #include <openssl/err.h>
129
130 #ifdef BN_DEBUG
131 # define PREDICT
132 #endif
133
134 /* #define PREDICT 1 */
135
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;
143
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 unsigned long locking_thread = 0; /* valid iff crypto_lock_rand is set */
149
150
151 #ifdef PREDICT
152 int rand_predictable=0;
153 #endif
154
155 const char *RAND_version="RAND" OPENSSL_VERSION_PTEXT;
156
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);
163
164 RAND_METHOD rand_ssleay_meth={
165 ssleay_rand_seed,
166 ssleay_rand_bytes,
167 ssleay_rand_cleanup,
168 ssleay_rand_add,
169 ssleay_rand_pseudo_bytes,
170 ssleay_rand_status
171 };
172
RAND_SSLeay(void)173 RAND_METHOD *RAND_SSLeay(void)
174 {
175 return(&rand_ssleay_meth);
176 }
177
ssleay_rand_cleanup(void)178 static void ssleay_rand_cleanup(void)
179 {
180 OPENSSL_cleanse(state,sizeof(state));
181 state_num=0;
182 state_index=0;
183 OPENSSL_cleanse(md,MD_DIGEST_LENGTH);
184 md_count[0]=0;
185 md_count[1]=0;
186 entropy=0;
187 initialized=0;
188 }
189
ssleay_rand_add(const void * buf,int num,double add)190 static void ssleay_rand_add(const void *buf, int num, double add)
191 {
192 int i,j,k,st_idx;
193 long md_c[2];
194 unsigned char local_md[MD_DIGEST_LENGTH];
195 EVP_MD_CTX m;
196 int do_not_lock;
197
198 /*
199 * (Based on the rand(3) manpage)
200 *
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
210 * hash function.
211 */
212
213 /* check if we already have the lock */
214 if (crypto_lock_rand)
215 {
216 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
217 do_not_lock = (locking_thread == CRYPTO_thread_id());
218 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
219 }
220 else
221 do_not_lock = 0;
222
223 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
224 st_idx=state_index;
225
226 /* use our own copies of the counters so that even
227 * if a concurrent thread seeds with exactly the
228 * same data and uses the same subarray there's _some_
229 * difference */
230 md_c[0] = md_count[0];
231 md_c[1] = md_count[1];
232
233 memcpy(local_md, md, sizeof md);
234
235 /* state_index <= state_num <= STATE_SIZE */
236 state_index += num;
237 if (state_index >= STATE_SIZE)
238 {
239 state_index%=STATE_SIZE;
240 state_num=STATE_SIZE;
241 }
242 else if (state_num < STATE_SIZE)
243 {
244 if (state_index > state_num)
245 state_num=state_index;
246 }
247 /* state_index <= state_num <= STATE_SIZE */
248
249 /* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE]
250 * are what we will use now, but other threads may use them
251 * as well */
252
253 md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
254
255 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
256
257 EVP_MD_CTX_init(&m);
258 for (i=0; i<num; i+=MD_DIGEST_LENGTH)
259 {
260 j=(num-i);
261 j=(j > MD_DIGEST_LENGTH)?MD_DIGEST_LENGTH:j;
262
263 MD_Init(&m);
264 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
265 k=(st_idx+j)-STATE_SIZE;
266 if (k > 0)
267 {
268 MD_Update(&m,&(state[st_idx]),j-k);
269 MD_Update(&m,&(state[0]),k);
270 }
271 else
272 MD_Update(&m,&(state[st_idx]),j);
273
274 MD_Update(&m,buf,j);
275 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
276 MD_Final(&m,local_md);
277 md_c[1]++;
278
279 buf=(const char *)buf + j;
280
281 for (k=0; k<j; k++)
282 {
283 /* Parallel threads may interfere with this,
284 * but always each byte of the new state is
285 * the XOR of some previous value of its
286 * and local_md (itermediate values may be lost).
287 * Alway using locking could hurt performance more
288 * than necessary given that conflicts occur only
289 * when the total seeding is longer than the random
290 * state. */
291 state[st_idx++]^=local_md[k];
292 if (st_idx >= STATE_SIZE)
293 st_idx=0;
294 }
295 }
296 EVP_MD_CTX_cleanup(&m);
297
298 if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
299 /* Don't just copy back local_md into md -- this could mean that
300 * other thread's seeding remains without effect (except for
301 * the incremented counter). By XORing it we keep at least as
302 * much entropy as fits into md. */
303 for (k = 0; k < (int)sizeof(md); k++)
304 {
305 md[k] ^= local_md[k];
306 }
307 if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
308 entropy += add;
309 if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
310
311 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
312 assert(md_c[1] == md_count[1]);
313 #endif
314 }
315
ssleay_rand_seed(const void * buf,int num)316 static void ssleay_rand_seed(const void *buf, int num)
317 {
318 ssleay_rand_add(buf, num, (double)num);
319 }
320
ssleay_rand_bytes(unsigned char * buf,int num)321 static int ssleay_rand_bytes(unsigned char *buf, int num)
322 {
323 static volatile int stirred_pool = 0;
324 int i,j,k,st_num,st_idx;
325 int num_ceil;
326 int ok;
327 long md_c[2];
328 unsigned char local_md[MD_DIGEST_LENGTH];
329 EVP_MD_CTX m;
330 #ifndef GETPID_IS_MEANINGLESS
331 pid_t curr_pid = getpid();
332 #endif
333 int do_stir_pool = 0;
334
335 #ifdef PREDICT
336 if (rand_predictable)
337 {
338 static unsigned char val=0;
339
340 for (i=0; i<num; i++)
341 buf[i]=val++;
342 return(1);
343 }
344 #endif
345
346 if (num <= 0)
347 return 1;
348
349 EVP_MD_CTX_init(&m);
350 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
351 num_ceil = (1 + (num-1)/(MD_DIGEST_LENGTH/2)) * (MD_DIGEST_LENGTH/2);
352
353 /*
354 * (Based on the rand(3) manpage:)
355 *
356 * For each group of 10 bytes (or less), we do the following:
357 *
358 * Input into the hash function the local 'md' (which is initialized from
359 * the global 'md' before any bytes are generated), the bytes that are to
360 * be overwritten by the random bytes, and bytes from the 'state'
361 * (incrementing looping index). From this digest output (which is kept
362 * in 'md'), the top (up to) 10 bytes are returned to the caller and the
363 * bottom 10 bytes are xored into the 'state'.
364 *
365 * Finally, after we have finished 'num' random bytes for the
366 * caller, 'count' (which is incremented) and the local and global 'md'
367 * are fed into the hash function and the results are kept in the
368 * global 'md'.
369 */
370
371 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
372
373 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
374 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
375 locking_thread = CRYPTO_thread_id();
376 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
377 crypto_lock_rand = 1;
378
379 if (!initialized)
380 {
381 RAND_poll();
382 initialized = 1;
383 }
384
385 if (!stirred_pool)
386 do_stir_pool = 1;
387
388 ok = (entropy >= ENTROPY_NEEDED);
389 if (!ok)
390 {
391 /* If the PRNG state is not yet unpredictable, then seeing
392 * the PRNG output may help attackers to determine the new
393 * state; thus we have to decrease the entropy estimate.
394 * Once we've had enough initial seeding we don't bother to
395 * adjust the entropy count, though, because we're not ambitious
396 * to provide *information-theoretic* randomness.
397 *
398 * NOTE: This approach fails if the program forks before
399 * we have enough entropy. Entropy should be collected
400 * in a separate input pool and be transferred to the
401 * output pool only when the entropy limit has been reached.
402 */
403 entropy -= num;
404 if (entropy < 0)
405 entropy = 0;
406 }
407
408 if (do_stir_pool)
409 {
410 /* In the output function only half of 'md' remains secret,
411 * so we better make sure that the required entropy gets
412 * 'evenly distributed' through 'state', our randomness pool.
413 * The input function (ssleay_rand_add) chains all of 'md',
414 * which makes it more suitable for this purpose.
415 */
416
417 int n = STATE_SIZE; /* so that the complete pool gets accessed */
418 while (n > 0)
419 {
420 #if MD_DIGEST_LENGTH > 20
421 # error "Please adjust DUMMY_SEED."
422 #endif
423 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
424 /* Note that the seed does not matter, it's just that
425 * ssleay_rand_add expects to have something to hash. */
426 ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
427 n -= MD_DIGEST_LENGTH;
428 }
429 if (ok)
430 stirred_pool = 1;
431 }
432
433 st_idx=state_index;
434 st_num=state_num;
435 md_c[0] = md_count[0];
436 md_c[1] = md_count[1];
437 memcpy(local_md, md, sizeof md);
438
439 state_index+=num_ceil;
440 if (state_index > state_num)
441 state_index %= state_num;
442
443 /* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num]
444 * are now ours (but other threads may use them too) */
445
446 md_count[0] += 1;
447
448 /* before unlocking, we must clear 'crypto_lock_rand' */
449 crypto_lock_rand = 0;
450 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
451
452 while (num > 0)
453 {
454 /* num_ceil -= MD_DIGEST_LENGTH/2 */
455 j=(num >= MD_DIGEST_LENGTH/2)?MD_DIGEST_LENGTH/2:num;
456 num-=j;
457 MD_Init(&m);
458 #ifndef GETPID_IS_MEANINGLESS
459 if (curr_pid) /* just in the first iteration to save time */
460 {
461 MD_Update(&m,(unsigned char*)&curr_pid,sizeof curr_pid);
462 curr_pid = 0;
463 }
464 #endif
465 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
466 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
467 #ifndef PURIFY
468 MD_Update(&m,buf,j); /* purify complains */
469 #endif
470 k=(st_idx+MD_DIGEST_LENGTH/2)-st_num;
471 if (k > 0)
472 {
473 MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2-k);
474 MD_Update(&m,&(state[0]),k);
475 }
476 else
477 MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2);
478 MD_Final(&m,local_md);
479
480 for (i=0; i<MD_DIGEST_LENGTH/2; i++)
481 {
482 state[st_idx++]^=local_md[i]; /* may compete with other threads */
483 if (st_idx >= st_num)
484 st_idx=0;
485 if (i < j)
486 *(buf++)=local_md[i+MD_DIGEST_LENGTH/2];
487 }
488 }
489
490 MD_Init(&m);
491 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
492 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
493 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
494 MD_Update(&m,md,MD_DIGEST_LENGTH);
495 MD_Final(&m,md);
496 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
497
498 EVP_MD_CTX_cleanup(&m);
499 if (ok)
500 return(1);
501 else
502 {
503 RANDerr(RAND_F_SSLEAY_RAND_BYTES,RAND_R_PRNG_NOT_SEEDED);
504 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
505 "http://www.openssl.org/support/faq.html");
506 return(0);
507 }
508 }
509
510 /* pseudo-random bytes that are guaranteed to be unique but not
511 unpredictable */
ssleay_rand_pseudo_bytes(unsigned char * buf,int num)512 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
513 {
514 int ret;
515 unsigned long err;
516
517 ret = RAND_bytes(buf, num);
518 if (ret == 0)
519 {
520 err = ERR_peek_error();
521 if (ERR_GET_LIB(err) == ERR_LIB_RAND &&
522 ERR_GET_REASON(err) == RAND_R_PRNG_NOT_SEEDED)
523 ERR_clear_error();
524 }
525 return (ret);
526 }
527
ssleay_rand_status(void)528 static int ssleay_rand_status(void)
529 {
530 int ret;
531 int do_not_lock;
532
533 /* check if we already have the lock
534 * (could happen if a RAND_poll() implementation calls RAND_status()) */
535 if (crypto_lock_rand)
536 {
537 CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
538 do_not_lock = (locking_thread == CRYPTO_thread_id());
539 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
540 }
541 else
542 do_not_lock = 0;
543
544 if (!do_not_lock)
545 {
546 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
547
548 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
549 CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
550 locking_thread = CRYPTO_thread_id();
551 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
552 crypto_lock_rand = 1;
553 }
554
555 if (!initialized)
556 {
557 RAND_poll();
558 initialized = 1;
559 }
560
561 ret = entropy >= ENTROPY_NEEDED;
562
563 if (!do_not_lock)
564 {
565 /* before unlocking, we must clear 'crypto_lock_rand' */
566 crypto_lock_rand = 0;
567
568 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
569 }
570
571 return ret;
572 }
573