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_FIPSEVP
126 #include <openssl/crypto.h>
127 #include <openssl/rand.h>
128 #include "rand_lcl.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 };
144 static double entropy
= 0;
145 static int initialized
= 0;
147 static unsigned int crypto_lock_rand
= 0; /* may be set only when a thread
148 * holds CRYPTO_LOCK_RAND (to
149 * prevent double locking) */
150 /* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */
151 /* valid iff crypto_lock_rand is set */
152 static CRYPTO_THREADID locking_threadid
;
155 int rand_predictable
= 0;
158 const char RAND_version
[] = "RAND" OPENSSL_VERSION_PTEXT
;
160 static void ssleay_rand_cleanup(void);
161 static void ssleay_rand_seed(const void *buf
, int num
);
162 static void ssleay_rand_add(const void *buf
, int num
, double add_entropy
);
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 void ssleay_rand_add(const void *buf
, int num
, double add
)
197 unsigned char local_md
[MD_DIGEST_LENGTH
];
205 * (Based on the rand(3) manpage)
207 * The input is chopped up into units of 20 bytes (or less for
208 * the last block). Each of these blocks is run through the hash
209 * function as follows: The data passed to the hash function
210 * is the current 'md', the same number of bytes from the 'state'
211 * (the location determined by in incremented looping index) as
212 * the current 'block', the new key data 'block', and 'count'
213 * (which is incremented after each use).
214 * The result of this is kept in 'md' and also xored into the
215 * 'state' at the same locations that were used as input into the
219 /* check if we already have the lock */
220 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 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
231 st_idx
= state_index
;
234 * use our own copies of the counters so that even if a concurrent thread
235 * seeds with exactly the same data and uses the same subarray there's
238 md_c
[0] = md_count
[0];
239 md_c
[1] = md_count
[1];
241 memcpy(local_md
, md
, sizeof md
);
243 /* state_index <= state_num <= STATE_SIZE */
245 if (state_index
>= STATE_SIZE
) {
246 state_index
%= STATE_SIZE
;
247 state_num
= STATE_SIZE
;
248 } else if (state_num
< STATE_SIZE
) {
249 if (state_index
> state_num
)
250 state_num
= state_index
;
252 /* state_index <= state_num <= STATE_SIZE */
255 * state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE] are what we
256 * will use now, but other threads may use them as well
259 md_count
[1] += (num
/ MD_DIGEST_LENGTH
) + (num
% MD_DIGEST_LENGTH
> 0);
262 CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
265 for (i
= 0; i
< num
; i
+= MD_DIGEST_LENGTH
) {
267 j
= (j
> MD_DIGEST_LENGTH
) ? MD_DIGEST_LENGTH
: j
;
270 MD_Update(&m
, local_md
, MD_DIGEST_LENGTH
);
271 k
= (st_idx
+ j
) - STATE_SIZE
;
273 MD_Update(&m
, &(state
[st_idx
]), j
- k
);
274 MD_Update(&m
, &(state
[0]), k
);
276 MD_Update(&m
, &(state
[st_idx
]), j
);
278 /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
279 MD_Update(&m
, buf
, j
);
281 * We know that line may cause programs such as purify and valgrind
282 * to complain about use of uninitialized data. The problem is not,
283 * it's with the caller. Removing that line will make sure you get
284 * really bad randomness and thereby other problems such as very
288 MD_Update(&m
, (unsigned char *)&(md_c
[0]), sizeof(md_c
));
289 MD_Final(&m
, local_md
);
292 buf
= (const char *)buf
+ j
;
294 for (k
= 0; k
< j
; k
++) {
296 * Parallel threads may interfere with this, but always each byte
297 * of the new state is the XOR of some previous value of its and
298 * local_md (itermediate values may be lost). Alway using locking
299 * could hurt performance more than necessary given that
300 * conflicts occur only when the total seeding is longer than the
303 state
[st_idx
++] ^= local_md
[k
];
304 if (st_idx
>= STATE_SIZE
)
308 EVP_MD_CTX_cleanup(&m
);
311 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
313 * Don't just copy back local_md into md -- this could mean that other
314 * thread's seeding remains without effect (except for the incremented
315 * counter). By XORing it we keep at least as much entropy as fits into
318 for (k
= 0; k
< (int)sizeof(md
); k
++) {
319 md
[k
] ^= local_md
[k
];
321 if (entropy
< ENTROPY_NEEDED
) /* stop counting when we have enough */
324 CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
326 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
327 assert(md_c
[1] == md_count
[1]);
331 static void ssleay_rand_seed(const void *buf
, int num
)
333 ssleay_rand_add(buf
, num
, (double)num
);
336 int ssleay_rand_bytes(unsigned char *buf
, int num
, int pseudo
, int lock
)
338 static volatile int stirred_pool
= 0;
339 int i
, j
, k
, st_num
, st_idx
;
343 unsigned char local_md
[MD_DIGEST_LENGTH
];
345 #ifndef GETPID_IS_MEANINGLESS
346 pid_t curr_pid
= getpid();
348 int do_stir_pool
= 0;
351 if (rand_predictable
) {
352 static unsigned char val
= 0;
354 for (i
= 0; i
< num
; i
++)
364 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
366 (1 + (num
- 1) / (MD_DIGEST_LENGTH
/ 2)) * (MD_DIGEST_LENGTH
/ 2);
369 * (Based on the rand(3) manpage:)
371 * For each group of 10 bytes (or less), we do the following:
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'.
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
386 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
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;
402 ok
= (entropy
>= ENTROPY_NEEDED
);
405 * If the PRNG state is not yet unpredictable, then seeing the PRNG
406 * output may help attackers to determine the new state; thus we have
407 * to decrease the entropy estimate. Once we've had enough initial
408 * seeding we don't bother to adjust the entropy count, though,
409 * because we're not ambitious to provide *information-theoretic*
410 * randomness. NOTE: This approach fails if the program forks before
411 * we have enough entropy. Entropy should be collected in a separate
412 * input pool and be transferred to the output pool only when the
413 * entropy limit has been reached.
422 * In the output function only half of 'md' remains secret, so we
423 * better make sure that the required entropy gets 'evenly
424 * distributed' through 'state', our randomness pool. The input
425 * function (ssleay_rand_add) chains all of 'md', which makes it more
426 * suitable for this purpose.
429 int n
= STATE_SIZE
; /* so that the complete pool gets accessed */
431 #if MD_DIGEST_LENGTH > 20
432 # error "Please adjust DUMMY_SEED."
434 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
436 * Note that the seed does not matter, it's just that
437 * ssleay_rand_add expects to have something to hash.
439 ssleay_rand_add(DUMMY_SEED
, MD_DIGEST_LENGTH
, 0.0);
440 n
-= MD_DIGEST_LENGTH
;
446 st_idx
= state_index
;
448 md_c
[0] = md_count
[0];
449 md_c
[1] = md_count
[1];
450 memcpy(local_md
, md
, sizeof md
);
452 state_index
+= num_ceil
;
453 if (state_index
> state_num
)
454 state_index
%= state_num
;
457 * state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num] are now
458 * ours (but other threads may use them too)
463 /* before unlocking, we must clear 'crypto_lock_rand' */
464 crypto_lock_rand
= 0;
466 CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
469 /* num_ceil -= MD_DIGEST_LENGTH/2 */
470 j
= (num
>= MD_DIGEST_LENGTH
/ 2) ? MD_DIGEST_LENGTH
/ 2 : num
;
473 #ifndef GETPID_IS_MEANINGLESS
474 if (curr_pid
) { /* just in the first iteration to save time */
475 MD_Update(&m
, (unsigned char *)&curr_pid
, sizeof curr_pid
);
479 MD_Update(&m
, local_md
, MD_DIGEST_LENGTH
);
480 MD_Update(&m
, (unsigned char *)&(md_c
[0]), sizeof(md_c
));
482 #ifndef PURIFY /* purify complains */
484 * The following line uses the supplied buffer as a small source of
485 * entropy: since this buffer is often uninitialised it may cause
486 * programs such as purify or valgrind to complain. So for those
487 * builds it is not used: the removal of such a small source of
488 * entropy has negligible impact on security.
490 MD_Update(&m
, buf
, j
);
493 k
= (st_idx
+ MD_DIGEST_LENGTH
/ 2) - st_num
;
495 MD_Update(&m
, &(state
[st_idx
]), MD_DIGEST_LENGTH
/ 2 - k
);
496 MD_Update(&m
, &(state
[0]), k
);
498 MD_Update(&m
, &(state
[st_idx
]), MD_DIGEST_LENGTH
/ 2);
499 MD_Final(&m
, local_md
);
501 for (i
= 0; i
< MD_DIGEST_LENGTH
/ 2; i
++) {
502 /* may compete with other threads */
503 state
[st_idx
++] ^= local_md
[i
];
504 if (st_idx
>= st_num
)
507 *(buf
++) = local_md
[i
+ MD_DIGEST_LENGTH
/ 2];
512 MD_Update(&m
, (unsigned char *)&(md_c
[0]), sizeof(md_c
));
513 MD_Update(&m
, local_md
, MD_DIGEST_LENGTH
);
515 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
516 MD_Update(&m
, md
, MD_DIGEST_LENGTH
);
519 CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
521 EVP_MD_CTX_cleanup(&m
);
527 RANDerr(RAND_F_SSLEAY_RAND_BYTES
, RAND_R_PRNG_NOT_SEEDED
);
528 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
529 "http://www.openssl.org/support/faq.html");
534 static int ssleay_rand_nopseudo_bytes(unsigned char *buf
, int num
)
536 return ssleay_rand_bytes(buf
, num
, 0, 1);
540 * pseudo-random bytes that are guaranteed to be unique but not unpredictable
542 static int ssleay_rand_pseudo_bytes(unsigned char *buf
, int num
)
544 return ssleay_rand_bytes(buf
, num
, 1, 1);
547 static int ssleay_rand_status(void)
553 CRYPTO_THREADID_current(&cur
);
555 * check if we already have the lock (could happen if a RAND_poll()
556 * implementation calls RAND_status())
558 if (crypto_lock_rand
) {
559 CRYPTO_r_lock(CRYPTO_LOCK_RAND2
);
560 do_not_lock
= !CRYPTO_THREADID_cmp(&locking_threadid
, &cur
);
561 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2
);
566 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
569 * prevent ssleay_rand_bytes() from trying to obtain the lock again
571 CRYPTO_w_lock(CRYPTO_LOCK_RAND2
);
572 CRYPTO_THREADID_cpy(&locking_threadid
, &cur
);
573 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2
);
574 crypto_lock_rand
= 1;
582 ret
= entropy
>= ENTROPY_NEEDED
;
585 /* before unlocking, we must clear 'crypto_lock_rand' */
586 crypto_lock_rand
= 0;
588 CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);