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 CPUFAM_X86 || CPUFAM_AMD64
165 extern int rand_quick_x86ish_rdrand(rand_pool */
*r*/
);
168 static quick__functype
*pick_quick(void)
170 #if CPUFAM_X86 || CPUFAM_AMD64
171 DISPATCH_PICK_COND(rand_quick
, rand_quick_x86ish_rdrand
,
172 cpu_feature_p(CPUFEAT_X86_RDRAND
));
174 DISPATCH_PICK_FALLBACK(rand_quick
, trivial_quick
);
177 int rand_quick(rand_pool
*r
) { RAND_RESOLVE(r
); return (quick(r
)); }
179 /* --- @rand_seed@ --- *
181 * Arguments: @rand_pool *r@ = pointer to a randomness pool
182 * @unsigned bits@ = number of bits to ensure
186 * Use: Ensures that there are at least @bits@ good bits of entropy
187 * in the pool. It is recommended that you call this after
188 * initializing a new pool. Requesting @bits > RAND_IBITS@ is
189 * doomed to failure (and is an error).
192 void rand_seed(rand_pool
*r
, unsigned bits
)
196 assert(((void)"bits pointlessly large in rand_seed", bits
<= RAND_IBITS
));
197 assert(((void)"no noise source in rand_seed", r
->s
));
199 while (r
->ibits
< bits
)
204 /* --- @rand_key@ --- *
206 * Arguments: @rand_pool *r@ = pointer to a randomness pool
207 * @const void *k@ = pointer to key data
208 * @size_t sz@ = size of key data
212 * Use: Sets the secret key for a randomness pool. The key is used
213 * when mixing in new random bits.
216 void rand_key(rand_pool
*r
, const void *k
, size_t sz
)
220 static const char label
[] = "Catacomb random pool key";
224 assert(HASH_SZ
>= RAND_KEYSZ
);
226 HASH(&hc
, label
, sizeof(label
));
227 if (sz
) HASH(&hc
, k
, sz
);
229 memcpy(r
->k
.k
, h
, RAND_KEYSZ
);
232 /* --- @rand_add@ --- *
234 * Arguments: @rand_pool *r@ = pointer to a randomness pool
235 * @const void *p@ = pointer a buffer of data to add
236 * @size_t sz@ = size of the data buffer
237 * @unsigned goodbits@ = number of good bits estimated in buffer
241 * Use: Mixes the data in the buffer with the contents of the
242 * pool. The estimate of the number of good bits is added to
243 * the pool's own count. The mixing operation is not
244 * cryptographically strong. However, data in the input pool
245 * isn't output directly, only through the one-way gating
246 * operation, so that shouldn't matter.
249 void rand_add(rand_pool
*r
, const void *p
, size_t sz
, unsigned goodbits
)
254 STATIC_ASSERT(RAND_POOLSZ
== 128, "Polynomial doesn't match pool size");
258 i
= r
->i
; rot
= r
->irot
;
262 r
->pool
[i
] ^= (ROL8(o
, rot
) ^
263 r
->pool
[(i
+ 1) % RAND_POOLSZ
] ^
264 r
->pool
[(i
+ 2) % RAND_POOLSZ
] ^
265 r
->pool
[(i
+ 7) % RAND_POOLSZ
]);
267 i
++; if (i
>= RAND_POOLSZ
) i
-= RAND_POOLSZ
;
273 r
->ibits
+= goodbits
;
274 if (r
->ibits
> RAND_IBITS
)
275 r
->ibits
= RAND_IBITS
;
278 /* --- @rand_goodbits@ --- *
280 * Arguments: @rand_pool *r@ = pointer to a randomness pool
282 * Returns: Estimate of the number of good bits remaining in the pool.
285 unsigned rand_goodbits(rand_pool
*r
)
288 return (r
->ibits
+ r
->obits
);
291 /* --- @rand_gate@ --- *
293 * Arguments: @rand_pool *r@ = pointer to a randomness pool
297 * Use: Mixes up the entire state of the generator in a nonreversible
301 void rand_gate(rand_pool
*r
)
303 octet h
[HASH_SZ
], g
[4];
307 STATIC_ASSERT(CIPHER_KEYSZ
<= HASH_SZ
, "rand cipher keysize too long");
312 /* --- Hash up all the data in the pool --- */
315 STORE32(g
, r
->gen
); HASH(&hc
, g
, sizeof(g
));
316 HASH(&hc
, r
->k
.k
, RAND_KEYSZ
);
317 HASH(&hc
, r
->pool
, RAND_POOLSZ
);
318 HASH(&hc
, r
->buf
, RAND_BUFSZ
);
322 /* --- Now mangle all of the data based on the hash --- */
324 CIPHER_INIT(&cc
, h
, CIPHER_KEYSZ
, 0);
325 CIPHER_ENCRYPT(&cc
, r
->pool
, r
->pool
, RAND_POOLSZ
);
326 CIPHER_ENCRYPT(&cc
, r
->buf
, r
->buf
, RAND_BUFSZ
);
329 /* --- Reset the various state variables --- */
332 r
->obits
+= r
->ibits
;
333 if (r
->obits
> RAND_OBITS
) {
334 r
->ibits
= r
->obits
- r
->ibits
;
335 r
->obits
= RAND_OBITS
;
341 /* --- @rand_stretch@ --- *
343 * Arguments: @rand_pool *r@ = pointer to a randomness pool
347 * Use: Stretches the contents of the output buffer by transforming
348 * it in a nonreversible way. This doesn't add any entropy
349 * worth speaking about, but it works well enough when the
350 * caller doesn't care about that sort of thing.
353 void rand_stretch(rand_pool
*r
)
355 octet h
[HASH_SZ
], g
[4];
359 STATIC_ASSERT(CIPHER_KEYSZ
<= HASH_SZ
, "rand cipher keysize too long");
364 /* --- Hash up all the data in the buffer --- */
367 STORE32(g
, r
->gen
); HASH(&hc
, g
, sizeof(g
));
368 HASH(&hc
, r
->k
.k
, RAND_KEYSZ
);
369 HASH(&hc
, r
->pool
, RAND_POOLSZ
);
370 HASH(&hc
, r
->buf
, RAND_BUFSZ
);
374 /* --- Now mangle the buffer based on the hash --- */
376 CIPHER_INIT(&cc
, h
, CIPHER_KEYSZ
, 0);
377 CIPHER_ENCRYPT(&cc
, r
->buf
, r
->buf
, RAND_BUFSZ
);
380 /* --- Reset the various state variables --- */
386 /* --- @rand_get@ --- *
388 * Arguments: @rand_pool *r@ = pointer to a randomness pool
389 * @void *p@ = pointer to output buffer
390 * @size_t sz@ = size of output buffer
394 * Use: Gets random data from the pool. The pool's contents can't be
395 * determined from the output of this function; nor can the
396 * output data be determined from a knowledge of the data input
397 * to the pool wihtout also having knowledge of the secret key.
398 * The good bits counter is decremented, although no special
399 * action is taken if it reaches zero.
402 void rand_get(rand_pool
*r
, void *p
, size_t sz
)
413 if (r
->o
+ sz
<= RAND_BUFSZ
) {
414 memcpy(o
, r
->buf
+ r
->o
, sz
);
418 size_t chunk
= RAND_BUFSZ
- r
->o
;
420 memcpy(o
, r
->buf
+ r
->o
, chunk
);
428 if (r
->obits
> sz
* 8)
434 /* --- @rand_getgood@ --- *
436 * Arguments: @rand_pool *r@ = pointer to a randomness pool
437 * @void *p@ = pointer to output buffer
438 * @size_t sz@ = size of output buffer
442 * Use: Gets random data from the pool, ensuring that there are
443 * enough good bits. This interface isn't recommended: it makes
444 * the generator slow, and doesn't provide much more security
445 * than @rand_get@, assuming you've previously done a
449 void rand_getgood(rand_pool
*r
, void *p
, size_t sz
)
457 if (!r
->s
|| !r
->s
->getnoise
) {
467 if (chunk
* 8 > r
->obits
) {
468 if (chunk
* 8 > r
->ibits
+ r
->obits
)
469 do r
->s
->getnoise(r
); while (r
->ibits
+ r
->obits
< 256);
471 if (chunk
* 8 > r
->obits
)
472 chunk
= r
->obits
/ 8;
475 if (chunk
+ r
->o
> RAND_BUFSZ
)
476 chunk
= RAND_BUFSZ
- r
->o
;
478 memcpy(o
, r
->buf
+ r
->o
, chunk
);
480 r
->obits
-= chunk
* 8;
486 /*----- Generic random number generator interface -------------------------*/
488 static void gdestroy(grand
*r
)
491 if (g
!= &rand_global
) {
497 static int gmisc(grand
*r
, unsigned op
, ...)
506 switch (va_arg(ap
, unsigned)) {
509 case GRAND_SEEDUINT32
:
510 case GRAND_SEEDBLOCK
:
527 case GRAND_SEEDINT
: {
528 unsigned u
= va_arg(ap
, unsigned);
529 rand_add(&g
->p
, &u
, sizeof(u
), sizeof(u
));
531 case GRAND_SEEDUINT32
: {
532 uint32 i
= va_arg(ap
, uint32
);
533 rand_add(&g
->p
, &i
, sizeof(i
), 4);
535 case GRAND_SEEDBLOCK
: {
536 const void *p
= va_arg(ap
, const void *);
537 size_t sz
= va_arg(ap
, size_t);
538 rand_add(&g
->p
, p
, sz
, sz
);
540 case GRAND_SEEDRAND
: {
541 grand
*rr
= va_arg(ap
, grand
*);
543 rr
->ops
->fill(rr
, buf
, sizeof(buf
));
544 rand_add(&g
->p
, buf
, sizeof(buf
), 8);
553 const void *k
= va_arg(ap
, const void *);
554 size_t sz
= va_arg(ap
, size_t);
555 rand_key(&g
->p
, k
, sz
);
558 rand_noisesrc(&g
->p
, va_arg(ap
, const rand_source
*));
561 rand_seed(&g
->p
, va_arg(ap
, unsigned));
567 rc
= rand_goodbits(&g
->p
);
570 const void *p
= va_arg(ap
, const void *);
571 size_t sz
= va_arg(ap
, size_t);
572 unsigned goodbits
= va_arg(ap
, unsigned);
573 rand_add(&g
->p
, p
, sz
, goodbits
);
584 static octet
gbyte(grand
*r
)
588 rand_getgood(&g
->p
, &o
, 1);
592 static uint32
gword(grand
*r
)
596 rand_getgood(&g
->p
, &b
, sizeof(b
));
600 static void gfill(grand
*r
, void *p
, size_t sz
)
603 rand_get(&g
->p
, p
, sz
);
606 static const grand_ops gops
= {
610 gword
, gbyte
, gword
, grand_defaultrange
, gfill
613 /* --- @rand_create@ --- *
617 * Returns: Pointer to a generic generator.
619 * Use: Constructs a generic generator interface over a Catacomb
620 * entropy pool generator.
623 grand
*rand_create(void)
625 gctx
*g
= S_CREATE(gctx
);
631 /*----- That's all, folks -------------------------------------------------*/