2 * util/random.c - thread safe random generator, which is reasonably secure.
4 * Copyright (c) 2007, NLnet Labs. All rights reserved.
6 * This software is open source.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
15 * Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
19 * Neither the name of the NLNET LABS nor the names of its contributors may
20 * be used to endorse or promote products derived from this software without
21 * specific prior written permission.
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
25 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
26 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
27 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
28 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
33 * POSSIBILITY OF SUCH DAMAGE.
38 * Thread safe random functions. Similar to arc4random() with an explicit
39 * initialisation routine.
41 * The code in this file is based on arc4random from
42 * openssh-4.0p1/openbsd-compat/bsd-arc4random.c
43 * That code is also BSD licensed. Here is their statement:
45 * Copyright (c) 1996, David Mazieres <dm@uun.org>
46 * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
48 * Permission to use, copy, modify, and distribute this software for any
49 * purpose with or without fee is hereby granted, provided that the above
50 * copyright notice and this permission notice appear in all copies.
52 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
53 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
54 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
55 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
56 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
57 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
58 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
61 #include "util/random.h"
64 #include <openssl/rand.h>
65 #include <openssl/rc4.h>
66 #include <openssl/err.h>
67 #elif defined(HAVE_NSS)
76 * Max random value. Similar to RAND_MAX, but more portable
77 * (mingw uses only 15 bits random).
79 #define MAX_VALUE 0x7fffffff
83 * Struct with per-thread random state.
84 * Keeps SSL types away from the header file.
87 /** key used for arc4random generation */
89 /** keeps track of key usage */
93 /** Size of key to use (must be multiple of 8) */
96 /** Number of bytes to reseed after */
97 #define REKEY_BYTES (1 << 24)
99 /* (re)setup system seed */
101 ub_systemseed(unsigned int seed)
103 /* RAND_ is threadsafe, by the way */
106 unsigned char buf[256];
107 unsigned int v = seed;
109 for(i=0; i<256/sizeof(seed); i++) {
110 memmove(buf+i*sizeof(seed), &v, sizeof(seed));
111 v = v*seed + (unsigned int)i;
115 log_err("Random generator has no entropy "
116 "(error %ld)", ERR_get_error());
118 verbose(VERB_OPS, "openssl has no entropy, "
119 "seeding with time and pid");
124 /** reseed random generator */
126 ub_arc4random_stir(struct ub_randstate* s, struct ub_randstate* from)
128 /* not as unsigned char, but longerint so that it is
129 aligned properly on alignment sensitive platforms */
130 uint64_t rand_buf[SEED_SIZE/sizeof(uint64_t)];
133 memset(&s->rc4, 0, sizeof(s->rc4));
134 memset(rand_buf, 0xc, sizeof(rand_buf));
136 uint8_t* rbuf = (uint8_t*)rand_buf;
137 for(i=0; i<SEED_SIZE; i++)
138 rbuf[i] = (uint8_t)ub_random(from);
141 ub_systemseed((unsigned)getpid()^(unsigned)time(NULL));
142 if (RAND_bytes((unsigned char*)rand_buf,
143 (int)sizeof(rand_buf)) <= 0) {
144 /* very unlikely that this happens, since we seeded
145 * above, if it does; complain and keep going */
146 log_err("Couldn't obtain random bytes (error %ld)",
152 #ifdef HAVE_FIPS_MODE
154 /* RC4 is not allowed, get some trustworthy randomness */
155 /* double certainty here, this routine should not be
156 * called in FIPS_mode */
157 memset(rand_buf, 0, sizeof(rand_buf));
158 s->rc4_ready = REKEY_BYTES;
161 #endif /* FIPS_MODE */
162 RC4_set_key(&s->rc4, SEED_SIZE, (unsigned char*)rand_buf);
165 * Discard early keystream, as per recommendations in:
166 * http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
168 for(i = 0; i <= 256; i += sizeof(rand_buf))
169 RC4(&s->rc4, sizeof(rand_buf), (unsigned char*)rand_buf,
170 (unsigned char*)rand_buf);
172 memset(rand_buf, 0, sizeof(rand_buf));
174 s->rc4_ready = REKEY_BYTES;
178 ub_initstate(unsigned int seed, struct ub_randstate* from)
180 struct ub_randstate* s = (struct ub_randstate*)calloc(1, sizeof(*s));
182 log_err("malloc failure in random init");
186 #ifdef HAVE_FIPS_MODE
189 ub_arc4random_stir(s, from);
194 ub_random(struct ub_randstate* s)
197 #ifdef HAVE_FIPS_MODE
199 /* RC4 is not allowed, get some trustworthy randomness */
200 /* we use pseudo bytes: it tries to return secure randomness
201 * but returns 'something' if that fails. We need something
202 * else if it fails, because we cannot block here */
203 if(RAND_pseudo_bytes((unsigned char*)&r, (int)sizeof(r))
205 log_err("FIPSmode, no arc4random but RAND failed "
206 "(error %ld)", ERR_get_error());
208 return (long int)((r) % (((unsigned)MAX_VALUE + 1)));
210 #endif /* FIPS_MODE */
211 if (s->rc4_ready <= 0) {
212 ub_arc4random_stir(s, NULL);
215 RC4(&s->rc4, sizeof(r),
216 (unsigned char *)&r, (unsigned char *)&r);
217 s->rc4_ready -= sizeof(r);
218 return (long int)((r) % (((unsigned)MAX_VALUE + 1)));
221 #elif defined(HAVE_NSS)
223 /* not much to remember for NSS since we use its pk11_random, placeholder */
224 struct ub_randstate {
228 void ub_systemseed(unsigned int ATTR_UNUSED(seed))
232 struct ub_randstate* ub_initstate(unsigned int ATTR_UNUSED(seed),
233 struct ub_randstate* ATTR_UNUSED(from))
235 struct ub_randstate* s = (struct ub_randstate*)calloc(1, sizeof(*s));
237 log_err("malloc failure in random init");
243 long int ub_random(struct ub_randstate* ATTR_UNUSED(state))
246 /* random 31 bit value. */
247 SECStatus s = PK11_GenerateRandom((unsigned char*)&x, (int)sizeof(x));
248 if(s != SECSuccess) {
249 log_err("PK11_GenerateRandom error: %s",
250 PORT_ErrorToString(PORT_GetError()));
252 return x & MAX_VALUE;
255 #endif /* HAVE_SSL or HAVE_NSS */
258 ub_random_max(struct ub_randstate* state, long int x)
260 /* make sure we fetch in a range that is divisible by x. ignore
261 * values from d .. MAX_VALUE, instead draw a new number */
262 long int d = MAX_VALUE - (MAX_VALUE % x); /* d is divisible by x */
263 long int v = ub_random(state);
265 v = ub_random(state);
270 ub_randfree(struct ub_randstate* s)
274 /* user app must do RAND_cleanup(); */