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 -------------------------------------------------*/