2 * Copyright (c) 2017 W. Dean Freeman
3 * Copyright (c) 2013-2015 Mark R V Murray
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer
11 * in this position and unchanged.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 * This implementation of Fortuna is based on the descriptions found in
31 * ISBN 978-0-470-47424-2 "Cryptography Engineering" by Ferguson, Schneier
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
38 #include <sys/limits.h>
41 #include <sys/param.h>
42 #include <sys/kernel.h>
44 #include <sys/malloc.h>
45 #include <sys/mutex.h>
46 #include <sys/random.h>
48 #include <sys/sysctl.h>
49 #include <sys/systm.h>
51 #include <machine/cpu.h>
53 #include <crypto/rijndael/rijndael-api-fst.h>
54 #include <crypto/sha2/sha256.h>
56 #include <dev/random/hash.h>
57 #include <dev/random/randomdev.h>
58 #include <dev/random/random_harvestq.h>
59 #include <dev/random/uint128.h>
60 #include <dev/random/fortuna.h>
69 #include "unit_test.h"
71 #include <crypto/rijndael/rijndael-api-fst.h>
72 #include <crypto/sha2/sha256.h>
74 #include <dev/random/hash.h>
75 #include <dev/random/randomdev.h>
76 #include <dev/random/uint128.h>
77 #include <dev/random/fortuna.h>
81 #define RANDOM_FORTUNA_NPOOLS 32 /* The number of accumulation pools */
82 #define RANDOM_FORTUNA_DEFPOOLSIZE 64 /* The default pool size/length for a (re)seed */
83 #define RANDOM_FORTUNA_MAX_READ (1 << 20) /* Max bytes in a single read */
86 * The allowable range of RANDOM_FORTUNA_DEFPOOLSIZE. The default value is above.
87 * Making RANDOM_FORTUNA_DEFPOOLSIZE too large will mean a long time between reseeds,
88 * and too small may compromise initial security but get faster reseeds.
90 #define RANDOM_FORTUNA_MINPOOLSIZE 16
91 #define RANDOM_FORTUNA_MAXPOOLSIZE INT_MAX
92 CTASSERT(RANDOM_FORTUNA_MINPOOLSIZE <= RANDOM_FORTUNA_DEFPOOLSIZE);
93 CTASSERT(RANDOM_FORTUNA_DEFPOOLSIZE <= RANDOM_FORTUNA_MAXPOOLSIZE);
95 /* This algorithm (and code) presumes that RANDOM_KEYSIZE is twice as large as RANDOM_BLOCKSIZE */
96 CTASSERT(RANDOM_BLOCKSIZE == sizeof(uint128_t));
97 CTASSERT(RANDOM_KEYSIZE == 2*RANDOM_BLOCKSIZE);
99 /* Probes for dtrace(1) */
100 SDT_PROVIDER_DECLARE(random);
101 SDT_PROVIDER_DEFINE(random);
102 SDT_PROBE_DEFINE2(random, fortuna, event_processor, debug, "u_int", "struct fs_pool *");
105 * This is the beastie that needs protecting. It contains all of the
106 * state that we are excited about. Exactly one is instantiated.
108 static struct fortuna_state {
109 struct fs_pool { /* P_i */
110 u_int fsp_length; /* Only the first one is used by Fortuna */
111 struct randomdev_hash fsp_hash;
112 } fs_pool[RANDOM_FORTUNA_NPOOLS];
113 u_int fs_reseedcount; /* ReseedCnt */
114 uint128_t fs_counter; /* C */
115 struct randomdev_key fs_key; /* K */
116 u_int fs_minpoolsize; /* Extras */
117 /* Extras for the OS */
119 /* For use when 'pacing' the reseeds */
120 sbintime_t fs_lasttime;
127 static struct sysctl_ctx_list random_clist;
128 RANDOM_CHECK_UINT(fs_minpoolsize, RANDOM_FORTUNA_MINPOOLSIZE, RANDOM_FORTUNA_MAXPOOLSIZE);
130 static uint8_t zero_region[RANDOM_ZERO_BLOCKSIZE];
133 static void random_fortuna_pre_read(void);
134 static void random_fortuna_read(uint8_t *, u_int);
135 static bool random_fortuna_seeded(void);
136 static void random_fortuna_process_event(struct harvest_event *);
137 static void random_fortuna_init_alg(void *);
138 static void random_fortuna_deinit_alg(void *);
140 static void random_fortuna_reseed_internal(uint32_t *entropy_data, u_int blockcount);
142 struct random_algorithm random_alg_context = {
143 .ra_ident = "Fortuna",
144 .ra_init_alg = random_fortuna_init_alg,
145 .ra_deinit_alg = random_fortuna_deinit_alg,
146 .ra_pre_read = random_fortuna_pre_read,
147 .ra_read = random_fortuna_read,
148 .ra_seeded = random_fortuna_seeded,
149 .ra_event_processor = random_fortuna_process_event,
150 .ra_poolcount = RANDOM_FORTUNA_NPOOLS,
155 random_fortuna_init_alg(void *unused __unused)
159 struct sysctl_oid *random_fortuna_o;
162 RANDOM_RESEED_INIT_LOCK();
164 * Fortuna parameters. Do not adjust these unless you have
165 * have a very good clue about what they do!
167 fortuna_state.fs_minpoolsize = RANDOM_FORTUNA_DEFPOOLSIZE;
169 fortuna_state.fs_lasttime = 0;
170 random_fortuna_o = SYSCTL_ADD_NODE(&random_clist,
171 SYSCTL_STATIC_CHILDREN(_kern_random),
172 OID_AUTO, "fortuna", CTLFLAG_RW, 0,
173 "Fortuna Parameters");
174 SYSCTL_ADD_PROC(&random_clist,
175 SYSCTL_CHILDREN(random_fortuna_o), OID_AUTO,
176 "minpoolsize", CTLTYPE_UINT | CTLFLAG_RWTUN,
177 &fortuna_state.fs_minpoolsize, RANDOM_FORTUNA_DEFPOOLSIZE,
178 random_check_uint_fs_minpoolsize, "IU",
179 "Minimum pool size necessary to cause a reseed");
180 KASSERT(fortuna_state.fs_minpoolsize > 0, ("random: Fortuna threshold must be > 0 at startup"));
184 * FS&K - InitializePRNG()
188 for (i = 0; i < RANDOM_FORTUNA_NPOOLS; i++) {
189 randomdev_hash_init(&fortuna_state.fs_pool[i].fsp_hash);
190 fortuna_state.fs_pool[i].fsp_length = 0;
192 fortuna_state.fs_reseedcount = 0;
194 * FS&K - InitializeGenerator()
198 fortuna_state.fs_counter = UINT128_ZERO;
199 explicit_bzero(&fortuna_state.fs_key, sizeof(fortuna_state.fs_key));
204 random_fortuna_deinit_alg(void *unused __unused)
207 RANDOM_RESEED_DEINIT_LOCK();
208 explicit_bzero(&fortuna_state, sizeof(fortuna_state));
210 sysctl_ctx_free(&random_clist);
215 * FS&K - AddRandomEvent()
216 * Process a single stochastic event off the harvest queue
219 random_fortuna_process_event(struct harvest_event *event)
223 RANDOM_RESEED_LOCK();
225 * FS&K - P_i = P_i|<harvested stuff>
226 * Accumulate the event into the appropriate pool
227 * where each event carries the destination information.
229 * The hash_init() and hash_finish() calls are done in
230 * random_fortuna_pre_read().
232 * We must be locked against pool state modification which can happen
233 * during accumulation/reseeding and reading/regating.
235 pl = event->he_destination % RANDOM_FORTUNA_NPOOLS;
237 * We ignore low entropy static/counter fields towards the end of the
238 * he_event structure in order to increase measurable entropy when
239 * conducting SP800-90B entropy analysis measurements of seed material
243 KASSERT(event->he_size <= sizeof(event->he_entropy),
244 ("%s: event->he_size: %hhu > sizeof(event->he_entropy): %zu\n",
245 __func__, event->he_size, sizeof(event->he_entropy)));
246 randomdev_hash_iterate(&fortuna_state.fs_pool[pl].fsp_hash,
247 &event->he_somecounter, sizeof(event->he_somecounter));
248 randomdev_hash_iterate(&fortuna_state.fs_pool[pl].fsp_hash,
249 event->he_entropy, event->he_size);
252 * Don't wrap the length. This is a "saturating" add.
253 * XXX: FIX!!: We don't actually need lengths for anything but fs_pool[0],
254 * but it's been useful debugging to see them all.
256 fortuna_state.fs_pool[pl].fsp_length = MIN(RANDOM_FORTUNA_MAXPOOLSIZE,
257 fortuna_state.fs_pool[pl].fsp_length +
258 sizeof(event->he_somecounter) + event->he_size);
259 explicit_bzero(event, sizeof(*event));
260 RANDOM_RESEED_UNLOCK();
265 * This introduces new key material into the output generator.
266 * Additionally it increments the output generator's counter
267 * variable C. When C > 0, the output generator is seeded and
268 * will deliver output.
269 * The entropy_data buffer passed is a very specific size; the
270 * product of RANDOM_FORTUNA_NPOOLS and RANDOM_KEYSIZE.
273 random_fortuna_reseed_internal(uint32_t *entropy_data, u_int blockcount)
275 struct randomdev_hash context;
276 uint8_t hash[RANDOM_KEYSIZE];
278 RANDOM_RESEED_ASSERT_LOCK_OWNED();
280 * FS&K - K = Hd(K|s) where Hd(m) is H(H(0^512|m))
283 randomdev_hash_init(&context);
284 randomdev_hash_iterate(&context, zero_region, RANDOM_ZERO_BLOCKSIZE);
285 randomdev_hash_iterate(&context, &fortuna_state.fs_key, sizeof(fortuna_state.fs_key));
286 randomdev_hash_iterate(&context, entropy_data, RANDOM_KEYSIZE*blockcount);
287 randomdev_hash_finish(&context, hash);
288 randomdev_hash_init(&context);
289 randomdev_hash_iterate(&context, hash, RANDOM_KEYSIZE);
290 randomdev_hash_finish(&context, hash);
291 randomdev_encrypt_init(&fortuna_state.fs_key, hash);
292 explicit_bzero(hash, sizeof(hash));
293 /* Unblock the device if this is the first time we are reseeding. */
294 if (uint128_is_zero(fortuna_state.fs_counter))
296 uint128_increment(&fortuna_state.fs_counter);
300 * FS&K - GenerateBlocks()
301 * Generate a number of complete blocks of random output.
304 random_fortuna_genblocks(uint8_t *buf, u_int blockcount)
308 RANDOM_RESEED_ASSERT_LOCK_OWNED();
309 for (i = 0; i < blockcount; i++) {
311 * FS&K - r = r|E(K,C)
314 randomdev_encrypt(&fortuna_state.fs_key, &fortuna_state.fs_counter, buf, RANDOM_BLOCKSIZE);
315 buf += RANDOM_BLOCKSIZE;
316 uint128_increment(&fortuna_state.fs_counter);
321 * FS&K - PseudoRandomData()
322 * This generates no more than 2^20 bytes of data, and cleans up its
323 * internal state when finished. It is assumed that a whole number of
324 * blocks are available for writing; any excess generated will be
328 random_fortuna_genrandom(uint8_t *buf, u_int bytecount)
330 static uint8_t temp[RANDOM_BLOCKSIZE*(RANDOM_KEYS_PER_BLOCK)];
333 RANDOM_RESEED_ASSERT_LOCK_OWNED();
335 * FS&K - assert(n < 2^20 (== 1 MB)
336 * - r = first-n-bytes(GenerateBlocks(ceil(n/16)))
337 * - K = GenerateBlocks(2)
339 KASSERT((bytecount <= RANDOM_FORTUNA_MAX_READ), ("invalid single read request to Fortuna of %d bytes", bytecount));
340 blockcount = howmany(bytecount, RANDOM_BLOCKSIZE);
341 random_fortuna_genblocks(buf, blockcount);
342 random_fortuna_genblocks(temp, RANDOM_KEYS_PER_BLOCK);
343 randomdev_encrypt_init(&fortuna_state.fs_key, temp);
344 explicit_bzero(temp, sizeof(temp));
348 * FS&K - RandomData() (Part 1)
349 * Used to return processed entropy from the PRNG. There is a pre_read
350 * required to be present (but it can be a stub) in order to allow
351 * specific actions at the begin of the read.
354 random_fortuna_pre_read(void)
359 struct randomdev_hash context;
360 uint32_t s[RANDOM_FORTUNA_NPOOLS*RANDOM_KEYSIZE_WORDS];
361 uint8_t temp[RANDOM_KEYSIZE];
364 KASSERT(fortuna_state.fs_minpoolsize > 0, ("random: Fortuna threshold must be > 0"));
366 /* FS&K - Use 'getsbinuptime()' to prevent reseed-spamming. */
367 now = getsbinuptime();
369 RANDOM_RESEED_LOCK();
371 if (fortuna_state.fs_pool[0].fsp_length >= fortuna_state.fs_minpoolsize
373 /* FS&K - Use 'getsbinuptime()' to prevent reseed-spamming. */
374 && (now - fortuna_state.fs_lasttime > hz/10)
378 fortuna_state.fs_lasttime = now;
381 /* FS&K - ReseedCNT = ReseedCNT + 1 */
382 fortuna_state.fs_reseedcount++;
383 /* s = \epsilon at start */
384 for (i = 0; i < RANDOM_FORTUNA_NPOOLS; i++) {
385 /* FS&K - if Divides(ReseedCnt, 2^i) ... */
386 if ((fortuna_state.fs_reseedcount % (1 << i)) == 0) {
388 * FS&K - temp = (P_i)
392 randomdev_hash_finish(&fortuna_state.fs_pool[i].fsp_hash, temp);
393 randomdev_hash_init(&fortuna_state.fs_pool[i].fsp_hash);
394 fortuna_state.fs_pool[i].fsp_length = 0;
395 randomdev_hash_init(&context);
396 randomdev_hash_iterate(&context, temp, RANDOM_KEYSIZE);
397 randomdev_hash_finish(&context, s + i*RANDOM_KEYSIZE_WORDS);
401 SDT_PROBE2(random, fortuna, event_processor, debug, fortuna_state.fs_reseedcount, fortuna_state.fs_pool);
403 random_fortuna_reseed_internal(s, i < RANDOM_FORTUNA_NPOOLS ? i + 1 : RANDOM_FORTUNA_NPOOLS);
404 /* Clean up and secure */
405 explicit_bzero(s, sizeof(s));
406 explicit_bzero(temp, sizeof(temp));
407 explicit_bzero(&context, sizeof(context));
409 RANDOM_RESEED_UNLOCK();
413 * FS&K - RandomData() (Part 2)
414 * Main read from Fortuna, continued. May be called multiple times after
415 * the random_fortuna_pre_read() above.
416 * The supplied buf MUST be a multiple of RANDOM_BLOCKSIZE in size.
417 * Lots of code presumes this for efficiency, both here and in other
418 * routines. You are NOT allowed to break this!
421 random_fortuna_read(uint8_t *buf, u_int bytecount)
424 KASSERT((bytecount % RANDOM_BLOCKSIZE) == 0, ("%s(): bytecount (= %d) must be a multiple of %d", __func__, bytecount, RANDOM_BLOCKSIZE ));
425 RANDOM_RESEED_LOCK();
426 random_fortuna_genrandom(buf, bytecount);
427 RANDOM_RESEED_UNLOCK();
431 random_fortuna_seeded(void)
434 return (!uint128_is_zero(fortuna_state.fs_counter));