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/rand.h>
127 #include "rand_lcl.h"
129 #include <openssl/crypto.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};
143 static double entropy
=0;
144 static int initialized
=0;
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 */
154 int rand_predictable
=0;
157 const char RAND_version
[]="RAND" OPENSSL_VERSION_PTEXT
;
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_bytes(unsigned char *buf
, int num
, int pseudo
);
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
];
202 * (Based on the rand(3) manpage)
204 * The input is chopped up into units of 20 bytes (or less for
205 * the last block). Each of these blocks is run through the hash
206 * function as follows: The data passed to the hash function
207 * is the current 'md', the same number of bytes from the 'state'
208 * (the location determined by in incremented looping index) as
209 * the current 'block', the new key data 'block', and 'count'
210 * (which is incremented after each use).
211 * The result of this is kept in 'md' and also xored into the
212 * 'state' at the same locations that were used as input into the
216 /* check if we already have the lock */
217 if (crypto_lock_rand
)
220 CRYPTO_THREADID_current(&cur
);
221 CRYPTO_r_lock(CRYPTO_LOCK_RAND2
);
222 do_not_lock
= !CRYPTO_THREADID_cmp(&locking_threadid
, &cur
);
223 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2
);
228 if (!do_not_lock
) CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
231 /* use our own copies of the counters so that even
232 * if a concurrent thread seeds with exactly the
233 * same data and uses the same subarray there's _some_
235 md_c
[0] = md_count
[0];
236 md_c
[1] = md_count
[1];
238 memcpy(local_md
, md
, sizeof md
);
240 /* state_index <= state_num <= STATE_SIZE */
242 if (state_index
>= STATE_SIZE
)
244 state_index
%=STATE_SIZE
;
245 state_num
=STATE_SIZE
;
247 else if (state_num
< STATE_SIZE
)
249 if (state_index
> state_num
)
250 state_num
=state_index
;
252 /* state_index <= state_num <= STATE_SIZE */
254 /* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE]
255 * are what we will use now, but other threads may use them
258 md_count
[1] += (num
/ MD_DIGEST_LENGTH
) + (num
% MD_DIGEST_LENGTH
> 0);
260 if (!do_not_lock
) CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
263 for (i
=0; i
<num
; i
+=MD_DIGEST_LENGTH
)
266 j
=(j
> MD_DIGEST_LENGTH
)?MD_DIGEST_LENGTH
:j
;
269 MD_Update(&m
,local_md
,MD_DIGEST_LENGTH
);
270 k
=(st_idx
+j
)-STATE_SIZE
;
273 MD_Update(&m
,&(state
[st_idx
]),j
-k
);
274 MD_Update(&m
,&(state
[0]),k
);
277 MD_Update(&m
,&(state
[st_idx
]),j
);
279 /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
281 /* We know that line may cause programs such as
282 purify and valgrind to complain about use of
283 uninitialized data. The problem is not, it's
284 with the caller. Removing that line will make
285 sure you get really bad randomness and thereby
286 other problems such as very insecure keys. */
288 MD_Update(&m
,(unsigned char *)&(md_c
[0]),sizeof(md_c
));
289 MD_Final(&m
,local_md
);
292 buf
=(const char *)buf
+ j
;
296 /* Parallel threads may interfere with this,
297 * but always each byte of the new state is
298 * the XOR of some previous value of its
299 * and local_md (itermediate values may be lost).
300 * Alway using locking could hurt performance more
301 * than necessary given that conflicts occur only
302 * when the total seeding is longer than the random
304 state
[st_idx
++]^=local_md
[k
];
305 if (st_idx
>= STATE_SIZE
)
309 EVP_MD_CTX_cleanup(&m
);
311 if (!do_not_lock
) CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
312 /* Don't just copy back local_md into md -- this could mean that
313 * other thread's seeding remains without effect (except for
314 * the incremented counter). By XORing it we keep at least as
315 * much entropy as fits into md. */
316 for (k
= 0; k
< (int)sizeof(md
); k
++)
318 md
[k
] ^= local_md
[k
];
320 if (entropy
< ENTROPY_NEEDED
) /* stop counting when we have enough */
322 if (!do_not_lock
) CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
324 #if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)
325 assert(md_c
[1] == md_count
[1]);
329 static void ssleay_rand_seed(const void *buf
, int num
)
331 ssleay_rand_add(buf
, num
, (double)num
);
334 static int ssleay_rand_bytes(unsigned char *buf
, int num
, int pseudo
)
336 static volatile int stirred_pool
= 0;
337 int i
,j
,k
,st_num
,st_idx
;
341 unsigned char local_md
[MD_DIGEST_LENGTH
];
343 #ifndef GETPID_IS_MEANINGLESS
344 pid_t curr_pid
= getpid();
346 int do_stir_pool
= 0;
349 if (rand_predictable
)
351 static unsigned char val
=0;
353 for (i
=0; i
<num
; i
++)
363 /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
364 num_ceil
= (1 + (num
-1)/(MD_DIGEST_LENGTH
/2)) * (MD_DIGEST_LENGTH
/2);
367 * (Based on the rand(3) manpage:)
369 * For each group of 10 bytes (or less), we do the following:
371 * Input into the hash function the local 'md' (which is initialized from
372 * the global 'md' before any bytes are generated), the bytes that are to
373 * be overwritten by the random bytes, and bytes from the 'state'
374 * (incrementing looping index). From this digest output (which is kept
375 * in 'md'), the top (up to) 10 bytes are returned to the caller and the
376 * bottom 10 bytes are xored into the 'state'.
378 * Finally, after we have finished 'num' random bytes for the
379 * caller, 'count' (which is incremented) and the local and global 'md'
380 * are fed into the hash function and the results are kept in the
384 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
386 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
387 CRYPTO_w_lock(CRYPTO_LOCK_RAND2
);
388 CRYPTO_THREADID_current(&locking_threadid
);
389 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2
);
390 crypto_lock_rand
= 1;
401 ok
= (entropy
>= ENTROPY_NEEDED
);
404 /* If the PRNG state is not yet unpredictable, then seeing
405 * the PRNG output may help attackers to determine the new
406 * state; thus we have to decrease the entropy estimate.
407 * Once we've had enough initial seeding we don't bother to
408 * adjust the entropy count, though, because we're not ambitious
409 * to provide *information-theoretic* randomness.
411 * NOTE: This approach fails if the program forks before
412 * we have enough entropy. Entropy should be collected
413 * in a separate input pool and be transferred to the
414 * output pool only when the entropy limit has been reached.
423 /* In the output function only half of 'md' remains secret,
424 * so we better make sure that the required entropy gets
425 * 'evenly distributed' through 'state', our randomness pool.
426 * The input function (ssleay_rand_add) chains all of 'md',
427 * which makes it more suitable for this purpose.
430 int n
= STATE_SIZE
; /* so that the complete pool gets accessed */
433 #if MD_DIGEST_LENGTH > 20
434 # error "Please adjust DUMMY_SEED."
436 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
437 /* Note that the seed does not matter, it's just that
438 * 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
;
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
;
456 /* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num]
457 * are now ours (but other threads may use them too) */
461 /* before unlocking, we must clear 'crypto_lock_rand' */
462 crypto_lock_rand
= 0;
463 CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
467 /* num_ceil -= MD_DIGEST_LENGTH/2 */
468 j
=(num
>= MD_DIGEST_LENGTH
/2)?MD_DIGEST_LENGTH
/2:num
;
471 #ifndef GETPID_IS_MEANINGLESS
472 if (curr_pid
) /* just in the first iteration to save time */
474 MD_Update(&m
,(unsigned char*)&curr_pid
,sizeof curr_pid
);
478 MD_Update(&m
,local_md
,MD_DIGEST_LENGTH
);
479 MD_Update(&m
,(unsigned char *)&(md_c
[0]),sizeof(md_c
));
481 #ifndef PURIFY /* purify complains */
482 /* The following line uses the supplied buffer as a small
483 * source of entropy: since this buffer is often uninitialised
484 * it may cause programs such as purify or valgrind to
485 * complain. So for those builds it is not used: the removal
486 * of such a small source of entropy has negligible impact on
492 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
);
499 MD_Update(&m
,&(state
[st_idx
]),MD_DIGEST_LENGTH
/2);
500 MD_Final(&m
,local_md
);
502 for (i
=0; i
<MD_DIGEST_LENGTH
/2; i
++)
504 state
[st_idx
++]^=local_md
[i
]; /* may compete with other threads */
505 if (st_idx
>= st_num
)
508 *(buf
++)=local_md
[i
+MD_DIGEST_LENGTH
/2];
513 MD_Update(&m
,(unsigned char *)&(md_c
[0]),sizeof(md_c
));
514 MD_Update(&m
,local_md
,MD_DIGEST_LENGTH
);
515 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
516 MD_Update(&m
,md
,MD_DIGEST_LENGTH
);
518 CRYPTO_w_unlock(CRYPTO_LOCK_RAND
);
520 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);
539 /* pseudo-random bytes that are guaranteed to be unique but not
541 static int ssleay_rand_pseudo_bytes(unsigned char *buf
, int num
)
543 return ssleay_rand_bytes(buf
, num
, 1);
546 static int ssleay_rand_status(void)
552 CRYPTO_THREADID_current(&cur
);
553 /* check if we already have the lock
554 * (could happen if a RAND_poll() implementation calls RAND_status()) */
555 if (crypto_lock_rand
)
557 CRYPTO_r_lock(CRYPTO_LOCK_RAND2
);
558 do_not_lock
= !CRYPTO_THREADID_cmp(&locking_threadid
, &cur
);
559 CRYPTO_r_unlock(CRYPTO_LOCK_RAND2
);
566 CRYPTO_w_lock(CRYPTO_LOCK_RAND
);
568 /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
569 CRYPTO_w_lock(CRYPTO_LOCK_RAND2
);
570 CRYPTO_THREADID_cpy(&locking_threadid
, &cur
);
571 CRYPTO_w_unlock(CRYPTO_LOCK_RAND2
);
572 crypto_lock_rand
= 1;
581 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
);