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) 1998-2000 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).
122 #include "openssl/e_os.h"
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 /* This should be set to 1 only when ssleay_rand_add() is called inside
145 an already locked state, so it doesn't try to lock and thereby cause
146 a hang. And it should always be reset back to 0 before unlocking. */
147 static int add_do_not_lock=0;
150 int rand_predictable=0;
153 const char *RAND_version="RAND" OPENSSL_VERSION_PTEXT;
155 static void ssleay_rand_cleanup(void);
156 static void ssleay_rand_seed(const void *buf, int num);
157 static void ssleay_rand_add(const void *buf, int num, double add_entropy);
158 static int ssleay_rand_bytes(unsigned char *buf, int num);
159 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num);
160 static int ssleay_rand_status(void);
162 RAND_METHOD rand_ssleay_meth={
167 ssleay_rand_pseudo_bytes,
171 RAND_METHOD *RAND_SSLeay(void)
173 return(&rand_ssleay_meth);
176 static void ssleay_rand_cleanup(void)
178 memset(state,0,sizeof(state));
181 memset(md,0,MD_DIGEST_LENGTH);
187 static void ssleay_rand_add(const void *buf, int num, double add)
191 unsigned char local_md[MD_DIGEST_LENGTH];
195 * (Based on the rand(3) manpage)
197 * The input is chopped up into units of 20 bytes (or less for
198 * the last block). Each of these blocks is run through the hash
199 * function as follows: The data passed to the hash function
200 * is the current 'md', the same number of bytes from the 'state'
201 * (the location determined by in incremented looping index) as
202 * the current 'block', the new key data 'block', and 'count'
203 * (which is incremented after each use).
204 * The result of this is kept in 'md' and also xored into the
205 * 'state' at the same locations that were used as input into the
209 if (!add_do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
212 /* use our own copies of the counters so that even
213 * if a concurrent thread seeds with exactly the
214 * same data and uses the same subarray there's _some_
216 md_c[0] = md_count[0];
217 md_c[1] = md_count[1];
219 memcpy(local_md, md, sizeof md);
221 /* state_index <= state_num <= STATE_SIZE */
223 if (state_index >= STATE_SIZE)
225 state_index%=STATE_SIZE;
226 state_num=STATE_SIZE;
228 else if (state_num < STATE_SIZE)
230 if (state_index > state_num)
231 state_num=state_index;
233 /* state_index <= state_num <= STATE_SIZE */
235 /* state[st_idx], ..., state[(st_idx + num - 1) % STATE_SIZE]
236 * are what we will use now, but other threads may use them
239 md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
241 if (!add_do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
243 for (i=0; i<num; i+=MD_DIGEST_LENGTH)
246 j=(j > MD_DIGEST_LENGTH)?MD_DIGEST_LENGTH:j;
249 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
250 k=(st_idx+j)-STATE_SIZE;
253 MD_Update(&m,&(state[st_idx]),j-k);
254 MD_Update(&m,&(state[0]),k);
257 MD_Update(&m,&(state[st_idx]),j);
260 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
261 MD_Final(local_md,&m);
264 buf=(const char *)buf + j;
268 /* Parallel threads may interfere with this,
269 * but always each byte of the new state is
270 * the XOR of some previous value of its
271 * and local_md (itermediate values may be lost).
272 * Alway using locking could hurt performance more
273 * than necessary given that conflicts occur only
274 * when the total seeding is longer than the random
276 state[st_idx++]^=local_md[k];
277 if (st_idx >= STATE_SIZE)
281 memset((char *)&m,0,sizeof(m));
283 if (!add_do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
284 /* Don't just copy back local_md into md -- this could mean that
285 * other thread's seeding remains without effect (except for
286 * the incremented counter). By XORing it we keep at least as
287 * much entropy as fits into md. */
288 for (k = 0; k < sizeof md; k++)
290 md[k] ^= local_md[k];
292 if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
294 if (!add_do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
297 assert(md_c[1] == md_count[1]);
301 static void ssleay_rand_seed(const void *buf, int num)
303 ssleay_rand_add(buf, num, num);
306 static int ssleay_rand_bytes(unsigned char *buf, int num)
308 static volatile int stirred_pool = 0;
309 int i,j,k,st_num,st_idx;
312 unsigned char local_md[MD_DIGEST_LENGTH];
314 #ifndef GETPID_IS_MEANINGLESS
315 pid_t curr_pid = getpid();
317 int do_stir_pool = 0;
320 if (rand_predictable)
322 static unsigned char val=0;
324 for (i=0; i<num; i++)
331 * (Based on the rand(3) manpage:)
333 * For each group of 10 bytes (or less), we do the following:
335 * Input into the hash function the top 10 bytes from the
336 * local 'md' (which is initialized from the global 'md'
337 * before any bytes are generated), the bytes that are
338 * to be overwritten by the random bytes, and bytes from the
339 * 'state' (incrementing looping index). From this digest output
340 * (which is kept in 'md'), the top (up to) 10 bytes are
341 * returned to the caller and the bottom (up to) 10 bytes are xored
343 * Finally, after we have finished 'num' random bytes for the
344 * caller, 'count' (which is incremented) and the local and global 'md'
345 * are fed into the hash function and the results are kept in the
352 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
353 add_do_not_lock = 1; /* Since we call ssleay_rand_add while in
354 this locked state. */
360 ok = (entropy >= ENTROPY_NEEDED);
363 /* If the PRNG state is not yet unpredictable, then seeing
364 * the PRNG output may help attackers to determine the new
365 * state; thus we have to decrease the entropy estimate.
366 * Once we've had enough initial seeding we don't bother to
367 * adjust the entropy count, though, because we're not ambitious
368 * to provide *information-theoretic* randomness.
370 * NOTE: This approach fails if the program forks before
371 * we have enough entropy. Entropy should be collected
372 * in a separate input pool and be transferred to the
373 * output pool only when the entropy limit has been reached.
382 /* Our output function chains only half of 'md', so we better
383 * make sure that the required entropy gets 'evenly distributed'
384 * through 'state', our randomness pool. The input function
385 * (ssleay_rand_add) chains all of 'md', which makes it more
386 * suitable for this purpose.
389 int n = STATE_SIZE; /* so that the complete pool gets accessed */
392 #if MD_DIGEST_LENGTH > 20
393 # error "Please adjust DUMMY_SEED."
395 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
396 /* Note that the seed does not matter, it's just that
397 * ssleay_rand_add expects to have something to hash. */
398 ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
399 n -= MD_DIGEST_LENGTH;
407 md_c[0] = md_count[0];
408 md_c[1] = md_count[1];
409 memcpy(local_md, md, sizeof md);
412 if (state_index > state_num)
413 state_index %= state_num;
415 /* state[st_idx], ..., state[(st_idx + num - 1) % st_num]
416 * are now ours (but other threads may use them too) */
420 add_do_not_lock = 0; /* If this would ever be forgotten, we can
421 expect any evil god to eat our souls. */
422 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
426 j=(num >= MD_DIGEST_LENGTH/2)?MD_DIGEST_LENGTH/2:num;
429 #ifndef GETPID_IS_MEANINGLESS
430 if (curr_pid) /* just in the first iteration to save time */
432 MD_Update(&m,(unsigned char*)&curr_pid,sizeof curr_pid);
436 MD_Update(&m,&(local_md[MD_DIGEST_LENGTH/2]),MD_DIGEST_LENGTH/2);
437 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
439 MD_Update(&m,buf,j); /* purify complains */
444 MD_Update(&m,&(state[st_idx]),j-k);
445 MD_Update(&m,&(state[0]),k);
448 MD_Update(&m,&(state[st_idx]),j);
449 MD_Final(local_md,&m);
453 state[st_idx++]^=local_md[i]; /* may compete with other threads */
454 *(buf++)=local_md[i+MD_DIGEST_LENGTH/2];
455 if (st_idx >= st_num)
461 MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
462 MD_Update(&m,local_md,MD_DIGEST_LENGTH);
463 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
464 MD_Update(&m,md,MD_DIGEST_LENGTH);
466 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
468 memset(&m,0,sizeof(m));
473 RANDerr(RAND_F_SSLEAY_RAND_BYTES,RAND_R_PRNG_NOT_SEEDED);
474 ERR_add_error_data(1, "You need to read the OpenSSL FAQ, "
475 "http://www.openssl.org/support/faq.html");
480 /* pseudo-random bytes that are guaranteed to be unique but not
482 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
486 ret = RAND_bytes(buf, num);
489 err = ERR_peek_error();
490 if (ERR_GET_LIB(err) == ERR_LIB_RAND &&
491 ERR_GET_REASON(err) == RAND_R_PRNG_NOT_SEEDED)
492 (void)ERR_get_error();
497 static int ssleay_rand_status(void)
504 CRYPTO_w_lock(CRYPTO_LOCK_RAND);
506 ret = entropy >= ENTROPY_NEEDED;
507 CRYPTO_w_unlock(CRYPTO_LOCK_RAND);