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
, 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);
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
, int num
, double add
)
194 unsigned char local_md
[MD_DIGEST_LENGTH
];
199 * (Based on the rand(3) manpage)
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
213 /* check if we already have the lock */
214 if (crypto_lock_rand
)
217 CRYPTO_THREADID_current(&cur
);
218 CRYPTO_r_lock(CRYPTO_LOCK_RAND2
);
219 do_not_lock
= !CRYPTO_THREADID_cmp(&locking_threadid
, &cur
);
220 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2
);
225 if (!do_not_lock
) CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
228 /* use our own copies of the counters so that even
229 * if a concurrent thread seeds with exactly the
230 * same data and uses the same subarray there's _some_
232 md_c
[0] = md_count
[0];
233 md_c
[1] = md_count
[1];
235 memcpy(local_md
, md
, sizeof md
);
237 /* state_index <= state_num <= STATE_SIZE */
239 if (state_index
>= STATE_SIZE
)
241 state_index
%=STATE_SIZE
;
242 state_num
=STATE_SIZE
;
244 else if (state_num
< STATE_SIZE
)
246 if (state_index
> state_num
)
247 state_num
=state_index
;
249 /* state_index <= state_num <= STATE_SIZE */
251 /* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE]
252 * are what we will use now, but other threads may use them
255 md_count
[1] += (num
/ MD_DIGEST_LENGTH
) + (num
% MD_DIGEST_LENGTH
> 0);
257 if (!do_not_lock
) CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
260 for (i
=0; i
<num
; i
+=MD_DIGEST_LENGTH
)
263 j
=(j
> MD_DIGEST_LENGTH
)?MD_DIGEST_LENGTH
:j
;
266 MD_Update(&m
,local_md
,MD_DIGEST_LENGTH
);
267 k
=(st_idx
+j
)-STATE_SIZE
;
270 MD_Update(&m
,&(state
[st_idx
]),j
-k
);
271 MD_Update(&m
,&(state
[0]),k
);
274 MD_Update(&m
,&(state
[st_idx
]),j
);
277 MD_Update(&m
,(unsigned char *)&(md_c
[0]),sizeof(md_c
));
278 MD_Final(&m
,local_md
);
281 buf
=(const char *)buf
+ j
;
285 /* Parallel threads may interfere with this,
286 * but always each byte of the new state is
287 * the XOR of some previous value of its
288 * and local_md (itermediate values may be lost).
289 * Alway using locking could hurt performance more
290 * than necessary given that conflicts occur only
291 * when the total seeding is longer than the random
293 state
[st_idx
++]^=local_md
[k
];
294 if (st_idx
>= STATE_SIZE
)
298 EVP_MD_CTX_cleanup(&m
);
300 if (!do_not_lock
) CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
301 /* Don't just copy back local_md into md -- this could mean that
302 * other thread's seeding remains without effect (except for
303 * the incremented counter). By XORing it we keep at least as
304 * much entropy as fits into md. */
305 for (k
= 0; k
< (int)sizeof(md
); k
++)
307 md
[k
] ^= local_md
[k
];
309 if (entropy
< ENTROPY_NEEDED
) /* stop counting when we have enough */
311 if (!do_not_lock
) CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
313 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
314 assert(md_c
[1] == md_count
[1]);
318 static void ssleay_rand_seed(const void *buf
, int num
)
320 ssleay_rand_add(buf
, num
, (double)num
);
323 static int ssleay_rand_bytes(unsigned char *buf
, int num
)
325 static volatile int stirred_pool
= 0;
326 int i
,j
,k
,st_num
,st_idx
;
330 unsigned char local_md
[MD_DIGEST_LENGTH
];
332 #ifndef GETPID_IS_MEANINGLESS
333 pid_t curr_pid
= getpid();
335 int do_stir_pool
= 0;
338 if (rand_predictable
)
340 static unsigned char val
=0;
342 for (i
=0; i
<num
; i
++)
352 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
353 num_ceil
= (1 + (num
-1)/(MD_DIGEST_LENGTH
/2)) * (MD_DIGEST_LENGTH
/2);
356 * (Based on the rand(3) manpage:)
358 * For each group of 10 bytes (or less), we do the following:
360 * Input into the hash function the local 'md' (which is initialized from
361 * the global 'md' before any bytes are generated), the bytes that are to
362 * be overwritten by the random bytes, and bytes from the 'state'
363 * (incrementing looping index). From this digest output (which is kept
364 * in 'md'), the top (up to) 10 bytes are returned to the caller and the
365 * bottom 10 bytes are xored into the 'state'.
367 * Finally, after we have finished 'num' random bytes for the
368 * caller, 'count' (which is incremented) and the local and global 'md'
369 * are fed into the hash function and the results are kept in the
373 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
375 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
376 CRYPTO_w_lock(CRYPTO_LOCK_RAND2
);
377 CRYPTO_THREADID_current(&locking_threadid
);
378 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2
);
379 crypto_lock_rand
= 1;
390 ok
= (entropy
>= ENTROPY_NEEDED
);
393 /* If the PRNG state is not yet unpredictable, then seeing
394 * the PRNG output may help attackers to determine the new
395 * state; thus we have to decrease the entropy estimate.
396 * Once we've had enough initial seeding we don't bother to
397 * adjust the entropy count, though, because we're not ambitious
398 * to provide *information-theoretic* randomness.
400 * NOTE: This approach fails if the program forks before
401 * we have enough entropy. Entropy should be collected
402 * in a separate input pool and be transferred to the
403 * output pool only when the entropy limit has been reached.
412 /* In the output function only half of 'md' remains secret,
413 * so we better make sure that the required entropy gets
414 * 'evenly distributed' through 'state', our randomness pool.
415 * The input function (ssleay_rand_add) chains all of 'md',
416 * which makes it more suitable for this purpose.
419 int n
= STATE_SIZE
; /* so that the complete pool gets accessed */
422 #if MD_DIGEST_LENGTH > 20
423 # error "Please adjust DUMMY_SEED."
425 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
426 /* Note that the seed does not matter, it's just that
427 * ssleay_rand_add expects to have something to hash. */
428 ssleay_rand_add(DUMMY_SEED
, MD_DIGEST_LENGTH
, 0.0);
429 n
-= MD_DIGEST_LENGTH
;
437 md_c
[0] = md_count
[0];
438 md_c
[1] = md_count
[1];
439 memcpy(local_md
, md
, sizeof md
);
441 state_index
+=num_ceil
;
442 if (state_index
> state_num
)
443 state_index
%= state_num
;
445 /* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num]
446 * are now ours (but other threads may use them too) */
450 /* before unlocking, we must clear 'crypto_lock_rand' */
451 crypto_lock_rand
= 0;
452 CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
456 /* num_ceil -= MD_DIGEST_LENGTH/2 */
457 j
=(num
>= MD_DIGEST_LENGTH
/2)?MD_DIGEST_LENGTH
/2:num
;
460 #ifndef GETPID_IS_MEANINGLESS
461 if (curr_pid
) /* just in the first iteration to save time */
463 MD_Update(&m
,(unsigned char*)&curr_pid
,sizeof curr_pid
);
467 MD_Update(&m
,local_md
,MD_DIGEST_LENGTH
);
468 MD_Update(&m
,(unsigned char *)&(md_c
[0]),sizeof(md_c
));
470 MD_Update(&m
,buf
,j
); /* purify complains */
472 k
=(st_idx
+MD_DIGEST_LENGTH
/2)-st_num
;
475 MD_Update(&m
,&(state
[st_idx
]),MD_DIGEST_LENGTH
/2-k
);
476 MD_Update(&m
,&(state
[0]),k
);
479 MD_Update(&m
,&(state
[st_idx
]),MD_DIGEST_LENGTH
/2);
480 MD_Final(&m
,local_md
);
482 for (i
=0; i
<MD_DIGEST_LENGTH
/2; i
++)
484 state
[st_idx
++]^=local_md
[i
]; /* may compete with other threads */
485 if (st_idx
>= st_num
)
488 *(buf
++)=local_md
[i
+MD_DIGEST_LENGTH
/2];
493 MD_Update(&m
,(unsigned char *)&(md_c
[0]),sizeof(md_c
));
494 MD_Update(&m
,local_md
,MD_DIGEST_LENGTH
);
495 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
496 MD_Update(&m
,md
,MD_DIGEST_LENGTH
);
498 CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
500 EVP_MD_CTX_cleanup(&m
);
505 RANDerr(RAND_F_SSLEAY_RAND_BYTES
,RAND_R_PRNG_NOT_SEEDED
);
506 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
507 "http://www.openssl.org/support/faq.html");
512 /* pseudo-random bytes that are guaranteed to be unique but not
514 static int ssleay_rand_pseudo_bytes(unsigned char *buf
, int num
)
519 ret
= RAND_bytes(buf
, num
);
522 err
= ERR_peek_error();
523 if (ERR_GET_LIB(err
) == ERR_LIB_RAND
&&
524 ERR_GET_REASON(err
) == RAND_R_PRNG_NOT_SEEDED
)
530 static int ssleay_rand_status(void)
536 CRYPTO_THREADID_current(&cur
);
537 /* check if we already have the lock
538 * (could happen if a RAND_poll() implementation calls RAND_status()) */
539 if (crypto_lock_rand
)
541 CRYPTO_r_lock(CRYPTO_LOCK_RAND2
);
542 do_not_lock
= !CRYPTO_THREADID_cmp(&locking_threadid
, &cur
);
543 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2
);
550 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
552 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
553 CRYPTO_w_lock(CRYPTO_LOCK_RAND2
);
554 CRYPTO_THREADID_cpy(&locking_threadid
, &cur
);
555 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2
);
556 crypto_lock_rand
= 1;
565 ret
= entropy
>= ENTROPY_NEEDED
;
569 /* before unlocking, we must clear 'crypto_lock_rand' */
570 crypto_lock_rand
= 0;
572 CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);