3 * Secure random number generator
5 * (c) 1998 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Catacomb.
12 * Catacomb is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
17 * Catacomb is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License along with Catacomb; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
28 /*----- Header files ------------------------------------------------------*/
36 #include <mLib/bits.h>
48 #include "twofish-counter.h"
51 #define CIPHER_CTX twofish_counterctx
52 #define CIPHER_INIT twofish_counterinit
53 #define CIPHER_ENCRYPT twofish_counterencrypt
54 #define CIPHER_IVSZ TWOFISH_BLKSZ
55 #define CIPHER_KEYSZ TWOFISH_KEYSZ
57 #define HASH_CTX sha256_ctx
58 #define HASH_INIT sha256_init
59 #define HASH sha256_hash
60 #define HASH_DONE sha256_done
61 #define HASH_SZ SHA256_HASHSZ
63 /*----- Static variables --------------------------------------------------*/
65 static const grand_ops gops;
67 typedef struct rand__gctx {
76 { "Catacomb global random byte pool" },
80 /*----- Macros ------------------------------------------------------------*/
82 #define RAND_RESOLVE(r) \
83 do { if ((r) == RAND_GLOBAL) r = &rand_global.p; } while (0)
85 #define GENCHECK(r) do { \
86 unsigned gen = rand_generation(); \
87 if (r->gen != gen) { r->gen = gen; rand_gate(r); } \
90 static int quick(rand_pool *);
91 #define QUICK(r) do { \
93 if ((r)->s && (r)->s->timer) (r)->s->timer(r); \
96 /*----- Main code ---------------------------------------------------------*/
98 /* --- @rand_init@ --- *
100 * Arguments: @rand_pool *r@ = pointer to a randomness pool
104 * Use: Initializes a randomness pool. The pool doesn't start out
105 * very random: that's your job to sort out. A good suggestion
106 * would be to attach an appropriate noise source and call
110 void rand_init(rand_pool *r)
113 memset(r->pool, 0, sizeof(r->pool));
114 memset(r->buf, 0, sizeof(r->buf));
115 r->gen = rand_generation();
118 r->ibits = r->obits = 0;
120 r->s = &noise_source;
125 /* --- @rand_noisesrc@ --- *
127 * Arguments: @rand_pool *r@ = pointer to a randomness pool
128 * @const rand_source *s@ = pointer to source definition
132 * Use: Sets a noise source for a randomness pool. When the pool's
133 * estimate of good random bits falls to zero, the @getnoise@
134 * function is called, passing the pool handle as an argument.
135 * It is expected to increase the number of good bits by at
136 * least one, because it'll be called over and over again until
137 * there are enough bits to satisfy the caller. The @timer@
138 * function is called frequently throughout the generator's
142 void rand_noisesrc(rand_pool *r, const rand_source *s)
148 /* --- @rand_quick@ --- *
150 * Arguments: @rand_pool *r@ = pointer to a randomness pool
152 * Returns: Zero on success; @-1@ on failure.
154 * Use Attempts to use some machine-specific `quick' source of
155 * entropy to top up @r@. This may not do anything at all on
159 CPU_DISPATCH(static, return, int, quick, (rand_pool *r), (r),
160 pick_quick, trivial_quick);
162 static int trivial_quick(rand_pool *r) { return (-1); }
164 #if __GNUC__ && (CPUFAM_X86 || CPUFAM_AMD64)
165 static int rdrand_quick(rand_pool *r)
171 for (i = 0; i < 16; i++) {
172 __asm__ ("rdrand %0; setc %1" : "=r" (rr), "=g" (w) : : "cc");
174 rand_add(r, &rr, sizeof(rr), 8*sizeof(rr));
182 static quick__functype *pick_quick(void)
184 #if __GNUC__ && (CPUFAM_X86 || CPUFAM_AMD64)
185 DISPATCH_PICK_COND(rand_quick, rdrand_quick,
186 cpu_feature_p(CPUFEAT_X86_RDRAND));
188 DISPATCH_PICK_FALLBACK(rand_quick, trivial_quick);
191 int rand_quick(rand_pool *r) { RAND_RESOLVE(r); return (quick(r)); }
193 /* --- @rand_seed@ --- *
195 * Arguments: @rand_pool *r@ = pointer to a randomness pool
196 * @unsigned bits@ = number of bits to ensure
200 * Use: Ensures that there are at least @bits@ good bits of entropy
201 * in the pool. It is recommended that you call this after
202 * initializing a new pool. Requesting @bits > RAND_IBITS@ is
203 * doomed to failure (and is an error).
206 void rand_seed(rand_pool *r, unsigned bits)
210 assert(((void)"bits pointlessly large in rand_seed", bits <= RAND_IBITS));
211 assert(((void)"no noise source in rand_seed", r->s));
213 while (r->ibits < bits)
218 /* --- @rand_key@ --- *
220 * Arguments: @rand_pool *r@ = pointer to a randomness pool
221 * @const void *k@ = pointer to key data
222 * @size_t sz@ = size of key data
226 * Use: Sets the secret key for a randomness pool. The key is used
227 * when mixing in new random bits.
230 void rand_key(rand_pool *r, const void *k, size_t sz)
234 static const char label[] = "Catacomb random pool key";
238 assert(HASH_SZ >= RAND_KEYSZ);
240 HASH(&hc, label, sizeof(label));
241 if (sz) HASH(&hc, k, sz);
243 memcpy(r->k.k, h, RAND_KEYSZ);
246 /* --- @rand_add@ --- *
248 * Arguments: @rand_pool *r@ = pointer to a randomness pool
249 * @const void *p@ = pointer a buffer of data to add
250 * @size_t sz@ = size of the data buffer
251 * @unsigned goodbits@ = number of good bits estimated in buffer
255 * Use: Mixes the data in the buffer with the contents of the
256 * pool. The estimate of the number of good bits is added to
257 * the pool's own count. The mixing operation is not
258 * cryptographically strong. However, data in the input pool
259 * isn't output directly, only through the one-way gating
260 * operation, so that shouldn't matter.
263 void rand_add(rand_pool *r, const void *p, size_t sz, unsigned goodbits)
268 #if RAND_POOLSZ != 128
269 # error Polynomial in rand_add is out of date. Fix it.
274 i = r->i; rot = r->irot;
278 r->pool[i] ^= (ROL8(o, rot) ^
279 r->pool[(i + 1) % RAND_POOLSZ] ^
280 r->pool[(i + 2) % RAND_POOLSZ] ^
281 r->pool[(i + 7) % RAND_POOLSZ]);
283 i++; if (i >= RAND_POOLSZ) i -= RAND_POOLSZ;
289 r->ibits += goodbits;
290 if (r->ibits > RAND_IBITS)
291 r->ibits = RAND_IBITS;
294 /* --- @rand_goodbits@ --- *
296 * Arguments: @rand_pool *r@ = pointer to a randomness pool
298 * Returns: Estimate of the number of good bits remaining in the pool.
301 unsigned rand_goodbits(rand_pool *r)
304 return (r->ibits + r->obits);
307 /* --- @rand_gate@ --- *
309 * Arguments: @rand_pool *r@ = pointer to a randomness pool
313 * Use: Mixes up the entire state of the generator in a nonreversible
317 void rand_gate(rand_pool *r)
319 octet h[HASH_SZ], g[4];
326 /* --- Hash up all the data in the pool --- */
329 STORE32(g, r->gen); HASH(&hc, g, sizeof(g));
330 HASH(&hc, r->pool, RAND_POOLSZ);
331 HASH(&hc, r->buf, RAND_BUFSZ);
335 /* --- Now mangle all of the data based on the hash --- */
337 assert(CIPHER_KEYSZ <= HASH_SZ);
338 CIPHER_INIT(&cc, h, CIPHER_KEYSZ, 0);
339 CIPHER_ENCRYPT(&cc, r->pool, r->pool, RAND_POOLSZ);
340 CIPHER_ENCRYPT(&cc, r->buf, r->buf, RAND_BUFSZ);
343 /* --- Reset the various state variables --- */
346 r->obits += r->ibits;
347 if (r->obits > RAND_OBITS) {
348 r->ibits = r->obits - r->ibits;
349 r->obits = RAND_OBITS;
355 /* --- @rand_stretch@ --- *
357 * Arguments: @rand_pool *r@ = pointer to a randomness pool
361 * Use: Stretches the contents of the output buffer by transforming
362 * it in a nonreversible way. This doesn't add any entropy
363 * worth speaking about, but it works well enough when the
364 * caller doesn't care about that sort of thing.
367 void rand_stretch(rand_pool *r)
369 octet h[HASH_SZ], g[4];
376 /* --- Hash up all the data in the buffer --- */
379 STORE32(g, r->gen); HASH(&hc, g, sizeof(g));
380 HASH(&hc, r->pool, RAND_POOLSZ);
381 HASH(&hc, r->buf, RAND_BUFSZ);
385 /* --- Now mangle the buffer based on the hash --- */
387 assert(CIPHER_KEYSZ <= HASH_SZ);
388 CIPHER_INIT(&cc, h, CIPHER_KEYSZ, 0);
389 CIPHER_ENCRYPT(&cc, r->buf, r->buf, RAND_BUFSZ);
392 /* --- Reset the various state variables --- */
398 /* --- @rand_get@ --- *
400 * Arguments: @rand_pool *r@ = pointer to a randomness pool
401 * @void *p@ = pointer to output buffer
402 * @size_t sz@ = size of output buffer
406 * Use: Gets random data from the pool. The pool's contents can't be
407 * determined from the output of this function; nor can the
408 * output data be determined from a knowledge of the data input
409 * to the pool wihtout also having knowledge of the secret key.
410 * The good bits counter is decremented, although no special
411 * action is taken if it reaches zero.
414 void rand_get(rand_pool *r, void *p, size_t sz)
425 if (r->o + sz <= RAND_BUFSZ) {
426 memcpy(o, r->buf + r->o, sz);
430 size_t chunk = RAND_BUFSZ - r->o;
432 memcpy(o, r->buf + r->o, chunk);
440 if (r->obits > sz * 8)
446 /* --- @rand_getgood@ --- *
448 * Arguments: @rand_pool *r@ = pointer to a randomness pool
449 * @void *p@ = pointer to output buffer
450 * @size_t sz@ = size of output buffer
454 * Use: Gets random data from the pool, ensuring that there are
455 * enough good bits. This interface isn't recommended: it makes
456 * the generator slow, and doesn't provide much more security
457 * than @rand_get@, assuming you've previously done a
461 void rand_getgood(rand_pool *r, void *p, size_t sz)
469 if (!r->s || !r->s->getnoise) {
479 if (chunk * 8 > r->obits) {
480 if (chunk * 8 > r->ibits + r->obits)
481 do r->s->getnoise(r); while (r->ibits + r->obits < 256);
483 if (chunk * 8 > r->obits)
484 chunk = r->obits / 8;
487 if (chunk + r->o > RAND_BUFSZ)
488 chunk = RAND_BUFSZ - r->o;
490 memcpy(o, r->buf + r->o, chunk);
492 r->obits -= chunk * 8;
498 /*----- Generic random number generator interface -------------------------*/
500 static void gdestroy(grand *r)
503 if (g != &rand_global) {
509 static int gmisc(grand *r, unsigned op, ...)
518 switch (va_arg(ap, unsigned)) {
521 case GRAND_SEEDUINT32:
522 case GRAND_SEEDBLOCK:
539 case GRAND_SEEDINT: {
540 unsigned u = va_arg(ap, unsigned);
541 rand_add(&g->p, &u, sizeof(u), sizeof(u));
543 case GRAND_SEEDUINT32: {
544 uint32 i = va_arg(ap, uint32);
545 rand_add(&g->p, &i, sizeof(i), 4);
547 case GRAND_SEEDBLOCK: {
548 const void *p = va_arg(ap, const void *);
549 size_t sz = va_arg(ap, size_t);
550 rand_add(&g->p, p, sz, sz);
552 case GRAND_SEEDRAND: {
553 grand *rr = va_arg(ap, grand *);
555 rr->ops->fill(rr, buf, sizeof(buf));
556 rand_add(&g->p, buf, sizeof(buf), 8);
565 const void *k = va_arg(ap, const void *);
566 size_t sz = va_arg(ap, size_t);
567 rand_key(&g->p, k, sz);
570 rand_noisesrc(&g->p, va_arg(ap, const rand_source *));
573 rand_seed(&g->p, va_arg(ap, unsigned));
579 rc = rand_goodbits(&g->p);
582 const void *p = va_arg(ap, const void *);
583 size_t sz = va_arg(ap, size_t);
584 unsigned goodbits = va_arg(ap, unsigned);
585 rand_add(&g->p, p, sz, goodbits);
596 static octet gbyte(grand *r)
600 rand_getgood(&g->p, &o, 1);
604 static uint32 gword(grand *r)
608 rand_getgood(&g->p, &b, sizeof(b));
612 static void gfill(grand *r, void *p, size_t sz)
615 rand_get(&g->p, p, sz);
618 static const grand_ops gops = {
622 gword, gbyte, gword, grand_defaultrange, gfill
625 /* --- @rand_create@ --- *
629 * Returns: Pointer to a generic generator.
631 * Use: Constructs a generic generator interface over a Catacomb
632 * entropy pool generator.
635 grand *rand_create(void)
637 gctx *g = S_CREATE(gctx);
643 /*----- That's all, folks -------------------------------------------------*/