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 ------------------------------------------------------*/
34 #include <mLib/bits.h>
45 #include "twofish-counter.h"
48 #define CIPHER_CTX twofish_counterctx
49 #define CIPHER_INIT twofish_counterinit
50 #define CIPHER_ENCRYPT twofish_counterencrypt
51 #define CIPHER_IVSZ TWOFISH_BLKSZ
52 #define CIPHER_KEYSZ TWOFISH_KEYSZ
54 #define HASH_CTX sha256_ctx
55 #define HASH_INIT sha256_init
56 #define HASH sha256_hash
57 #define HASH_DONE sha256_done
58 #define HASH_SZ SHA256_HASHSZ
60 /*----- Static variables --------------------------------------------------*/
62 static const grand_ops gops
;
64 typedef struct rand__gctx
{
73 { "Catacomb global random byte pool" },
77 /*----- Macros ------------------------------------------------------------*/
79 #define RAND_RESOLVE(r) \
80 do { if ((r) == RAND_GLOBAL) r = &rand_global.p; } while (0)
82 #define TIMER(r) do { \
83 if ((r)->s && (r)->s->timer) \
87 /*----- Main code ---------------------------------------------------------*/
89 /* --- @rand_init@ --- *
91 * Arguments: @rand_pool *r@ = pointer to a randomness pool
95 * Use: Initializes a randomness pool. The pool doesn't start out
96 * very random: that's your job to sort out. A good suggestion
97 * would be to attach an appropriate noise source and call
101 void rand_init(rand_pool
*r
)
104 memset(r
->pool
, 0, sizeof(r
->pool
));
105 memset(r
->buf
, 0, sizeof(r
->buf
));
108 r
->ibits
= r
->obits
= 0;
110 r
->s
= &noise_source
;
115 /* --- @rand_noisesrc@ --- *
117 * Arguments: @rand_pool *r@ = pointer to a randomness pool
118 * @const rand_source *s@ = pointer to source definition
122 * Use: Sets a noise source for a randomness pool. When the pool's
123 * estimate of good random bits falls to zero, the @getnoise@
124 * function is called, passing the pool handle as an argument.
125 * It is expected to increase the number of good bits by at
126 * least one, because it'll be called over and over again until
127 * there are enough bits to satisfy the caller. The @timer@
128 * function is called frequently throughout the generator's
132 void rand_noisesrc(rand_pool
*r
, const rand_source
*s
)
138 /* --- @rand_seed@ --- *
140 * Arguments: @rand_pool *r@ = pointer to a randomness pool
141 * @unsigned bits@ = number of bits to ensure
145 * Use: Ensures that there are at least @bits@ good bits of entropy
146 * in the pool. It is recommended that you call this after
147 * initializing a new pool. Requesting @bits > RAND_IBITS@ is
148 * doomed to failure (and is an error).
151 void rand_seed(rand_pool
*r
, unsigned bits
)
155 assert(((void)"bits pointlessly large in rand_seed", bits
<= RAND_IBITS
));
156 assert(((void)"no noise source in rand_seed", r
->s
));
158 while (r
->ibits
< bits
)
163 /* --- @rand_key@ --- *
165 * Arguments: @rand_pool *r@ = pointer to a randomness pool
166 * @const void *k@ = pointer to key data
167 * @size_t sz@ = size of key data
171 * Use: Sets the secret key for a randomness pool. The key is used
172 * when mixing in new random bits.
175 void rand_key(rand_pool
*r
, const void *k
, size_t sz
)
179 static const char label
[] = "Catacomb random pool key";
183 assert(HASH_SZ
>= RAND_KEYSZ
);
185 HASH(&hc
, label
, sizeof(label
));
186 if (sz
) HASH(&hc
, k
, sz
);
188 memcpy(r
->k
.k
, h
, RAND_KEYSZ
);
191 /* --- @rand_add@ --- *
193 * Arguments: @rand_pool *r@ = pointer to a randomness pool
194 * @const void *p@ = pointer a buffer of data to add
195 * @size_t sz@ = size of the data buffer
196 * @unsigned goodbits@ = number of good bits estimated in buffer
200 * Use: Mixes the data in the buffer with the contents of the
201 * pool. The estimate of the number of good bits is added to
202 * the pool's own count. The mixing operation is not
203 * cryptographically strong. However, data in the input pool
204 * isn't output directly, only through the one-way gating
205 * operation, so that shouldn't matter.
208 void rand_add(rand_pool
*r
, const void *p
, size_t sz
, unsigned goodbits
)
213 #if RAND_POOLSZ != 128
214 # error Polynomial in rand_add is out of date. Fix it.
219 i
= r
->i
; rot
= r
->irot
;
223 r
->pool
[i
] ^= (ROL8(o
, rot
) ^
224 r
->pool
[(i
+ 1) % RAND_POOLSZ
] ^
225 r
->pool
[(i
+ 2) % RAND_POOLSZ
] ^
226 r
->pool
[(i
+ 7) % RAND_POOLSZ
]);
228 i
++; if (i
>= RAND_POOLSZ
) i
-= RAND_POOLSZ
;
234 r
->ibits
+= goodbits
;
235 if (r
->ibits
> RAND_IBITS
)
236 r
->ibits
= RAND_IBITS
;
239 /* --- @rand_goodbits@ --- *
241 * Arguments: @rand_pool *r@ = pointer to a randomness pool
243 * Returns: Estimate of the number of good bits remaining in the pool.
246 unsigned rand_goodbits(rand_pool
*r
)
249 return (r
->ibits
+ r
->obits
);
252 /* --- @rand_gate@ --- *
254 * Arguments: @rand_pool *r@ = pointer to a randomness pool
258 * Use: Mixes up the entire state of the generator in a nonreversible
262 void rand_gate(rand_pool
*r
)
271 /* --- Hash up all the data in the pool --- */
274 HASH(&hc
, r
->pool
, RAND_POOLSZ
);
275 HASH(&hc
, r
->buf
, RAND_BUFSZ
);
279 /* --- Now mangle all of the data based on the hash --- */
281 assert(CIPHER_KEYSZ
<= HASH_SZ
);
282 CIPHER_INIT(&cc
, h
, CIPHER_KEYSZ
, 0);
283 CIPHER_ENCRYPT(&cc
, r
->pool
, r
->pool
, RAND_POOLSZ
);
284 CIPHER_ENCRYPT(&cc
, r
->buf
, r
->buf
, RAND_BUFSZ
);
287 /* --- Reset the various state variables --- */
290 r
->obits
+= r
->ibits
;
291 if (r
->obits
> RAND_OBITS
) {
292 r
->ibits
= r
->obits
- r
->ibits
;
293 r
->obits
= RAND_OBITS
;
299 /* --- @rand_stretch@ --- *
301 * Arguments: @rand_pool *r@ = pointer to a randomness pool
305 * Use: Stretches the contents of the output buffer by transforming
306 * it in a nonreversible way. This doesn't add any entropy
307 * worth speaking about, but it works well enough when the
308 * caller doesn't care about that sort of thing.
311 void rand_stretch(rand_pool
*r
)
320 /* --- Hash up all the data in the buffer --- */
323 HASH(&hc
, r
->pool
, RAND_POOLSZ
);
324 HASH(&hc
, r
->buf
, RAND_BUFSZ
);
328 /* --- Now mangle the buffer based on the hash --- */
330 assert(CIPHER_KEYSZ
< HASH_SZ
);
331 CIPHER_INIT(&cc
, h
, CIPHER_KEYSZ
, 0);
332 CIPHER_ENCRYPT(&cc
, r
->buf
, r
->buf
, RAND_BUFSZ
);
335 /* --- Reset the various state variables --- */
341 /* --- @rand_get@ --- *
343 * Arguments: @rand_pool *r@ = pointer to a randomness pool
344 * @void *p@ = pointer to output buffer
345 * @size_t sz@ = size of output buffer
349 * Use: Gets random data from the pool. The pool's contents can't be
350 * determined from the output of this function; nor can the
351 * output data be determined from a knowledge of the data input
352 * to the pool wihtout also having knowledge of the secret key.
353 * The good bits counter is decremented, although no special
354 * action is taken if it reaches zero.
357 void rand_get(rand_pool
*r
, void *p
, size_t sz
)
367 if (r
->o
+ sz
<= RAND_BUFSZ
) {
368 memcpy(o
, r
->buf
+ r
->o
, sz
);
372 size_t chunk
= RAND_BUFSZ
- r
->o
;
374 memcpy(o
, r
->buf
+ r
->o
, chunk
);
382 if (r
->obits
> sz
* 8)
388 /* --- @rand_getgood@ --- *
390 * Arguments: @rand_pool *r@ = pointer to a randomness pool
391 * @void *p@ = pointer to output buffer
392 * @size_t sz@ = size of output buffer
396 * Use: Gets random data from the pool, ensuring that there are
397 * enough good bits. This interface isn't recommended: it makes
398 * the generator slow, and doesn't provide much more security
399 * than @rand_get@, assuming you've previously done a
403 void rand_getgood(rand_pool
*r
, void *p
, size_t sz
)
411 if (!r
->s
|| !r
->s
->getnoise
) {
420 if (chunk
* 8 > r
->obits
) {
421 if (chunk
* 8 > r
->ibits
+ r
->obits
)
422 do r
->s
->getnoise(r
); while (r
->ibits
+ r
->obits
< 256);
424 if (chunk
* 8 > r
->obits
)
425 chunk
= r
->obits
/ 8;
428 if (chunk
+ r
->o
> RAND_BUFSZ
)
429 chunk
= RAND_BUFSZ
- r
->o
;
431 memcpy(o
, r
->buf
+ r
->o
, chunk
);
433 r
->obits
-= chunk
* 8;
439 /*----- Generic random number generator interface -------------------------*/
441 static void gdestroy(grand
*r
)
444 if (g
!= &rand_global
) {
450 static int gmisc(grand
*r
, unsigned op
, ...)
459 switch (va_arg(ap
, unsigned)) {
462 case GRAND_SEEDUINT32
:
463 case GRAND_SEEDBLOCK
:
480 case GRAND_SEEDINT
: {
481 unsigned u
= va_arg(ap
, unsigned);
482 rand_add(&g
->p
, &u
, sizeof(u
), sizeof(u
));
484 case GRAND_SEEDUINT32
: {
485 uint32 i
= va_arg(ap
, uint32
);
486 rand_add(&g
->p
, &i
, sizeof(i
), 4);
488 case GRAND_SEEDBLOCK
: {
489 const void *p
= va_arg(ap
, const void *);
490 size_t sz
= va_arg(ap
, size_t);
491 rand_add(&g
->p
, p
, sz
, sz
);
493 case GRAND_SEEDRAND
: {
494 grand
*rr
= va_arg(ap
, grand
*);
496 rr
->ops
->fill(rr
, buf
, sizeof(buf
));
497 rand_add(&g
->p
, buf
, sizeof(buf
), 8);
506 const void *k
= va_arg(ap
, const void *);
507 size_t sz
= va_arg(ap
, size_t);
508 rand_key(&g
->p
, k
, sz
);
511 rand_noisesrc(&g
->p
, va_arg(ap
, const rand_source
*));
514 rand_seed(&g
->p
, va_arg(ap
, unsigned));
520 rc
= rand_goodbits(&g
->p
);
523 const void *p
= va_arg(ap
, const void *);
524 size_t sz
= va_arg(ap
, size_t);
525 unsigned goodbits
= va_arg(ap
, unsigned);
526 rand_add(&g
->p
, p
, sz
, goodbits
);
537 static octet
gbyte(grand
*r
)
541 rand_getgood(&g
->p
, &o
, 1);
545 static uint32
gword(grand
*r
)
549 rand_getgood(&g
->p
, &b
, sizeof(b
));
553 static void gfill(grand
*r
, void *p
, size_t sz
)
556 rand_get(&g
->p
, p
, sz
);
559 static const grand_ops gops
= {
563 gword
, gbyte
, gword
, grand_range
, gfill
566 /* --- @rand_create@ --- *
570 * Returns: Pointer to a generic generator.
572 * Use: Constructs a generic generator interface over a Catacomb
573 * entropy pool generator.
576 grand
*rand_create(void)
578 gctx
*g
= S_CREATE(gctx
);
584 /*----- That's all, folks -------------------------------------------------*/