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>
38 #include "blowfish-cbc.h"
42 #include "rmd160-hmac.h"
44 /*----- Static variables --------------------------------------------------*/
46 static const grand_ops gops
;
53 static gctx
*pool
= 0; /* Default random pool */
55 /*----- Macros ------------------------------------------------------------*/
57 #define RAND_RESOLVE(r) do { \
58 if ((r) == RAND_GLOBAL) { \
60 pool = (gctx *)rand_create(); \
65 #define TIMER(r) do { \
66 if ((r)->s && (r)->s->timer) \
70 /*----- Main code ---------------------------------------------------------*/
72 /* --- @rand_init@ --- *
74 * Arguments: @rand_pool *r@ = pointer to a randomness pool
78 * Use: Initializes a randomness pool. The pool doesn't start out
79 * very random: that's your job to sort out. A good suggestion
80 * would be to attach an appropriate noise source and call
84 void rand_init(rand_pool
*r
)
87 memset(r
->pool
, 0, sizeof(r
->pool
));
88 memset(r
->buf
, 0, sizeof(r
->buf
));
91 r
->ibits
= r
->obits
= 0;
94 rmd160_hmacinit(&r
->k
, 0, 0);
98 /* --- @rand_noisesrc@ --- *
100 * Arguments: @rand_pool *r@ = pointer to a randomness pool
101 * @const rand_source *s@ = pointer to source definition
105 * Use: Sets a noise source for a randomness pool. When the pool's
106 * estimate of good random bits falls to zero, the @getnoise@
107 * function is called, passing the pool handle as an argument.
108 * It is expected to increase the number of good bits by at
109 * least one, because it'll be called over and over again until
110 * there are enough bits to satisfy the caller. The @timer@
111 * function is called frequently throughout the generator's
115 void rand_noisesrc(rand_pool
*r
, const rand_source
*s
)
121 /* --- @rand_seed@ --- *
123 * Arguments: @rand_pool *r@ = pointer to a randomness pool
124 * @unsigned bits@ = number of bits to ensure
128 * Use: Ensures that there are at least @bits@ good bits of entropy
129 * in the pool. It is recommended that you call this after
130 * initializing a new pool. Requesting @bits > RAND_IBITS@ is
131 * doomed to failure (and is an error).
134 void rand_seed(rand_pool
*r
, unsigned bits
)
138 assert(((void)"bits pointlessly large in rand_seed", bits
<= RAND_IBITS
));
139 assert(((void)"no noise source in rand_seed", r
->s
));
141 while (r
->ibits
< bits
)
146 /* --- @rand_key@ --- *
148 * Arguments: @rand_pool *r@ = pointer to a randomness pool
149 * @const void *k@ = pointer to key data
150 * @size_t sz@ = size of key data
154 * Use: Sets the secret key for a randomness pool. The key is used
155 * when mixing in new random bits.
158 void rand_key(rand_pool
*r
, const void *k
, size_t sz
)
161 rmd160_hmacinit(&r
->k
, k
, sz
);
164 /* --- @rand_add@ --- *
166 * Arguments: @rand_pool *r@ = pointer to a randomness pool
167 * @const void *p@ = pointer a buffer of data to add
168 * @size_t sz@ = size of the data buffer
169 * @unsigned goodbits@ = number of good bits estimated in buffer
173 * Use: Mixes the data in the buffer with the contents of the
174 * pool. The estimate of the number of good bits is added to
175 * the pool's own count. The mixing operation is not
176 * cryptographically strong. However, data in the input pool
177 * isn't output directly, only through the one-way gating
178 * operation, so that shouldn't matter.
181 void rand_add(rand_pool
*r
, const void *p
, size_t sz
, unsigned goodbits
)
186 #if RAND_POOLSZ != 128
187 # error Polynomial in rand_add is out of date. Fix it.
192 i
= r
->i
; rot
= r
->irot
;
196 r
->pool
[i
] ^= (ROL8(o
, rot
) ^
197 r
->pool
[(i
+ 1) % RAND_POOLSZ
] ^
198 r
->pool
[(i
+ 2) % RAND_POOLSZ
] ^
199 r
->pool
[(i
+ 7) % RAND_POOLSZ
]);
201 i
++; if (i
>= RAND_POOLSZ
) i
-= RAND_POOLSZ
;
207 r
->ibits
+= goodbits
;
208 if (r
->ibits
> RAND_IBITS
)
209 r
->ibits
= RAND_IBITS
;
212 /* --- @rand_goodbits@ --- *
214 * Arguments: @rand_pool *r@ = pointer to a randomness pool
216 * Returns: Estimate of the number of good bits remaining in the pool.
219 unsigned rand_goodbits(rand_pool
*r
)
222 return (r
->ibits
+ r
->obits
);
225 /* --- @rand_gate@ --- *
227 * Arguments: @rand_pool *r@ = pointer to a randomness pool
231 * Use: Mixes up the entire state of the generator in a nonreversible
235 void rand_gate(rand_pool
*r
)
237 octet mac
[RMD160_HASHSZ
];
242 /* --- Hash up all the data in the pool --- */
247 rmd160_macinit(&mc
, &r
->k
);
248 rmd160_machash(&mc
, r
->pool
, sizeof(r
->pool
));
249 rmd160_machash(&mc
, r
->buf
, sizeof(r
->buf
));
250 rmd160_macdone(&mc
, mac
);
254 /* --- Now mangle all of the data based on the hash --- */
259 blowfish_cbcinit(&bc
, mac
, sizeof(mac
), 0);
260 blowfish_cbcencrypt(&bc
, r
->pool
, r
->pool
, sizeof(r
->pool
));
261 blowfish_cbcencrypt(&bc
, r
->buf
, r
->buf
, sizeof(r
->buf
));
265 /* --- Reset the various state variables --- */
268 r
->obits
+= r
->ibits
;
269 if (r
->obits
> RAND_OBITS
) {
270 r
->ibits
= r
->obits
- r
->ibits
;
271 r
->obits
= RAND_OBITS
;
277 /* --- @rand_stretch@ --- *
279 * Arguments: @rand_pool *r@ = pointer to a randomness pool
283 * Use: Stretches the contents of the output buffer by transforming
284 * it in a nonreversible way. This doesn't add any entropy
285 * worth speaking about, but it works well enough when the
286 * caller doesn't care about that sort of thing.
289 void rand_stretch(rand_pool
*r
)
291 octet mac
[RMD160_HASHSZ
];
296 /* --- Hash up all the data in the buffer --- */
301 rmd160_macinit(&mc
, &r
->k
);
302 rmd160_machash(&mc
, r
->pool
, sizeof(r
->pool
));
303 rmd160_machash(&mc
, r
->buf
, sizeof(r
->buf
));
304 rmd160_macdone(&mc
, mac
);
308 /* --- Now mangle the buffer based on that hash --- */
313 blowfish_cbcinit(&bc
, mac
, sizeof(mac
), 0);
314 blowfish_cbcencrypt(&bc
, r
->buf
, r
->buf
, sizeof(r
->buf
));
318 /* --- Reset the various state variables --- */
324 /* --- @rand_get@ --- *
326 * Arguments: @rand_pool *r@ = pointer to a randomness pool
327 * @void *p@ = pointer to output buffer
328 * @size_t sz@ = size of output buffer
332 * Use: Gets random data from the pool. The pool's contents can't be
333 * determined from the output of this function; nor can the
334 * output data be determined from a knowledge of the data input
335 * to the pool wihtout also having knowledge of the secret key.
336 * The good bits counter is decremented, although no special
337 * action is taken if it reaches zero.
340 void rand_get(rand_pool
*r
, void *p
, size_t sz
)
350 if (r
->o
+ sz
<= RAND_BUFSZ
) {
351 memcpy(o
, r
->buf
+ r
->o
, sz
);
355 size_t chunk
= RAND_BUFSZ
- r
->o
;
357 memcpy(o
, r
->buf
+ r
->o
, chunk
);
365 if (r
->obits
> sz
* 8)
371 /* --- @rand_getgood@ --- *
373 * Arguments: @rand_pool *r@ = pointer to a randomness pool
374 * @void *p@ = pointer to output buffer
375 * @size_t sz@ = size of output buffer
379 * Use: Gets random data from the pool, ensuring that there are
380 * enough good bits. This interface isn't recommended: it makes
381 * the generator slow, and doesn't provide much more security
382 * than @rand_get@, assuming you've previously done a
386 void rand_getgood(rand_pool
*r
, void *p
, size_t sz
)
394 if (!r
->s
|| !r
->s
->getnoise
) {
403 if (chunk
* 8 > r
->obits
) {
404 if (chunk
* 8 > r
->ibits
+ r
->obits
)
405 do r
->s
->getnoise(r
); while (r
->ibits
+ r
->obits
< 256);
407 if (chunk
* 8 > r
->obits
)
408 chunk
= r
->obits
/ 8;
411 if (chunk
+ r
->o
> RAND_BUFSZ
)
412 chunk
= RAND_BUFSZ
- r
->o
;
414 memcpy(o
, r
->buf
+ r
->o
, chunk
);
416 r
->obits
-= chunk
* 8;
422 /*----- Generic random number generator interface -------------------------*/
424 #define GRESOLVE(g, r) do { \
425 if (r != &rand_global) \
429 pool = (gctx *)rand_create(); \
434 static void gdestroy(grand
*r
)
444 static int gmisc(grand
*r
, unsigned op
, ...)
454 switch (va_arg(ap
, unsigned)) {
457 case GRAND_SEEDUINT32
:
458 case GRAND_SEEDBLOCK
:
475 case GRAND_SEEDINT
: {
476 unsigned u
= va_arg(ap
, unsigned);
477 rand_add(&g
->p
, &u
, sizeof(u
), sizeof(u
));
479 case GRAND_SEEDUINT32
: {
480 uint32 i
= va_arg(ap
, uint32
);
481 rand_add(&g
->p
, &i
, sizeof(i
), 4);
483 case GRAND_SEEDBLOCK
: {
484 const void *p
= va_arg(ap
, const void *);
485 size_t sz
= va_arg(ap
, size_t);
486 rand_add(&g
->p
, p
, sz
, sz
);
488 case GRAND_SEEDRAND
: {
489 grand
*rr
= va_arg(ap
, grand
*);
491 rr
->ops
->fill(rr
, buf
, sizeof(buf
));
492 rand_add(&g
->p
, buf
, sizeof(buf
), 8);
501 const void *k
= va_arg(ap
, const void *);
502 size_t sz
= va_arg(ap
, size_t);
503 rand_key(&g
->p
, k
, sz
);
506 rand_noisesrc(&g
->p
, va_arg(ap
, const rand_source
*));
509 rand_seed(&g
->p
, va_arg(ap
, unsigned));
515 rc
= rand_goodbits(&g
->p
);
518 const void *p
= va_arg(ap
, const void *);
519 size_t sz
= va_arg(ap
, size_t);
520 unsigned goodbits
= va_arg(ap
, unsigned);
521 rand_add(&g
->p
, p
, sz
, goodbits
);
532 static octet
gbyte(grand
*r
)
537 rand_getgood(&g
->p
, &o
, 1);
541 static uint32
gword(grand
*r
)
546 rand_getgood(&g
->p
, &b
, sizeof(b
));
550 static void gfill(grand
*r
, void *p
, size_t sz
)
554 rand_get(&g
->p
, p
, sz
);
557 static const grand_ops gops
= {
561 gword
, gbyte
, gword
, grand_range
, gfill
564 grand rand_global
= { &gops
};
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 -------------------------------------------------*/