mirror of
git://git.sv.gnu.org/coreutils.git
synced 2026-07-29 03:50:45 +02:00
New file, containing ISAAC code that was in shred.c.
Make state size runtime-configurable. (isaac_new, isaac_copy): New functions.
This commit is contained in:
Paul Eggert
@@ -0,0 +1,406 @@
|
||||
/* rand-isaac.c - ISAAC random number generator
|
||||
|
||||
Copyright (C) 1999-2005 Free Software Foundation, Inc.
|
||||
Copyright (C) 1997, 1998, 1999 Colin Plumb.
|
||||
|
||||
This program is free software; you can redistribute it and/or modify
|
||||
it under the terms of the GNU General Public License as published by
|
||||
the Free Software Foundation; either version 2, or (at your option)
|
||||
any later version.
|
||||
|
||||
This program is distributed in the hope that it will be useful,
|
||||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
GNU General Public License for more details.
|
||||
|
||||
You should have received a copy of the GNU General Public License
|
||||
along with this program; if not, write to the Free Software Foundation,
|
||||
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
||||
|
||||
Written by Colin Plumb. */
|
||||
|
||||
/*
|
||||
* --------------------------------------------------------------------
|
||||
* Bob Jenkins' cryptographic random number generator, ISAAC.
|
||||
* Hacked by Colin Plumb.
|
||||
*
|
||||
* We need a source of random numbers for some of the overwrite data
|
||||
* for shred. Cryptographically secure is desirable, but it's not
|
||||
* life-or-death so I can be a little bit experimental in the choice
|
||||
* of RNGs here.
|
||||
*
|
||||
* This generator is based somewhat on RC4, but has analysis
|
||||
* <http://burtleburtle.net/bob/rand/isaacafa.html>
|
||||
* pointing to it actually being better. I like it because it's nice
|
||||
* and fast, and because the author did good work analyzing it.
|
||||
* --------------------------------------------------------------------
|
||||
*/
|
||||
|
||||
|
||||
#ifdef HAVE_CONFIG_H
|
||||
# include <config.h>
|
||||
#endif
|
||||
|
||||
#include "system.h"
|
||||
#include "gethrxtime.h"
|
||||
|
||||
#include "rand-isaac.h"
|
||||
|
||||
#define ISAAC_SIZE(words) \
|
||||
(sizeof (struct isaac_state) - \
|
||||
(ISAAC_MAX_WORDS - words) * sizeof (uint32_t))
|
||||
|
||||
/*
|
||||
* Create a new state, optionally at the location specified. This
|
||||
* should be called to create/initialize each new isaac_state. 'words'
|
||||
* must be a power of 2, and should be at least 8. Smaller values give
|
||||
* less security.
|
||||
*/
|
||||
struct isaac_state *
|
||||
isaac_new (struct isaac_state *s, int words)
|
||||
{
|
||||
size_t w;
|
||||
size_t ss = ISAAC_SIZE (words);
|
||||
if (!s)
|
||||
{
|
||||
s = xmalloc (ss);
|
||||
}
|
||||
memset (s, 0, ss);
|
||||
s->words = words;
|
||||
s->log = 0;
|
||||
for (w=1; w<words; w<<=1, s->log++) {}
|
||||
return s;
|
||||
}
|
||||
|
||||
/*
|
||||
* Copy a state. Destination block must be at least as large as
|
||||
* source.
|
||||
*/
|
||||
void
|
||||
isaac_copy (struct isaac_state *dst, struct isaac_state *src)
|
||||
{
|
||||
memcpy(dst, src, ISAAC_SIZE (src->words));
|
||||
}
|
||||
|
||||
/*
|
||||
* Refill the entire R array, and update S.
|
||||
*/
|
||||
void
|
||||
isaac_refill (struct isaac_state *s, uint32_t r[/* s>-words */])
|
||||
{
|
||||
uint32_t a, b; /* Caches of a and b */
|
||||
uint32_t x, y; /* Temps needed by isaac_step macro */
|
||||
uint32_t *m = s->mm; /* Pointer into state array */
|
||||
uint32_t w = s->words;
|
||||
|
||||
a = s->a;
|
||||
b = s->b + (++s->c);
|
||||
|
||||
do
|
||||
{
|
||||
isaac_step (s, a << 13, a, b, m, w / 2, r);
|
||||
isaac_step (s, a >> 6, a, b, m + 1, w / 2, r + 1);
|
||||
isaac_step (s, a << 2, a, b, m + 2, w / 2, r + 2);
|
||||
isaac_step (s, a >> 16, a, b, m + 3, w / 2, r + 3);
|
||||
r += 4;
|
||||
}
|
||||
while ((m += 4) < s->mm + w / 2);
|
||||
do
|
||||
{
|
||||
isaac_step (s, a << 13, a, b, m, -w / 2, r);
|
||||
isaac_step (s, a >> 6, a, b, m + 1, -w / 2, r + 1);
|
||||
isaac_step (s, a << 2, a, b, m + 2, -w / 2, r + 2);
|
||||
isaac_step (s, a >> 16, a, b, m + 3, -w / 2, r + 3);
|
||||
r += 4;
|
||||
}
|
||||
while ((m += 4) < s->mm + w);
|
||||
s->a = a;
|
||||
s->b = b;
|
||||
}
|
||||
|
||||
/*
|
||||
* The basic seed-scrambling step for initialization, based on Bob
|
||||
* Jenkins' 256-bit hash.
|
||||
*/
|
||||
#define mix(a,b,c,d,e,f,g,h) \
|
||||
( a ^= b << 11, d += a, \
|
||||
b += c, b ^= c >> 2, e += b, \
|
||||
c += d, c ^= d << 8, f += c, \
|
||||
d += e, d ^= e >> 16, g += d, \
|
||||
e += f, e ^= f << 10, h += e, \
|
||||
f += g, f ^= g >> 4, a += f, \
|
||||
g += h, g ^= h << 8, b += g, \
|
||||
h += a, h ^= a >> 9, c += h, \
|
||||
a += b )
|
||||
|
||||
/* The basic ISAAC initialization pass. */
|
||||
void
|
||||
isaac_mix (struct isaac_state *s, uint32_t const seed[/* s->words */])
|
||||
{
|
||||
int i;
|
||||
uint32_t a = s->iv[0];
|
||||
uint32_t b = s->iv[1];
|
||||
uint32_t c = s->iv[2];
|
||||
uint32_t d = s->iv[3];
|
||||
uint32_t e = s->iv[4];
|
||||
uint32_t f = s->iv[5];
|
||||
uint32_t g = s->iv[6];
|
||||
uint32_t h = s->iv[7];
|
||||
uint32_t w = s->words;
|
||||
|
||||
for (i = 0; i < w; i += 8)
|
||||
{
|
||||
a += seed[i];
|
||||
b += seed[i + 1];
|
||||
c += seed[i + 2];
|
||||
d += seed[i + 3];
|
||||
e += seed[i + 4];
|
||||
f += seed[i + 5];
|
||||
g += seed[i + 6];
|
||||
h += seed[i + 7];
|
||||
|
||||
mix (a, b, c, d, e, f, g, h);
|
||||
|
||||
s->mm[i] = a;
|
||||
s->mm[i + 1] = b;
|
||||
s->mm[i + 2] = c;
|
||||
s->mm[i + 3] = d;
|
||||
s->mm[i + 4] = e;
|
||||
s->mm[i + 5] = f;
|
||||
s->mm[i + 6] = g;
|
||||
s->mm[i + 7] = h;
|
||||
}
|
||||
|
||||
s->iv[0] = a;
|
||||
s->iv[1] = b;
|
||||
s->iv[2] = c;
|
||||
s->iv[3] = d;
|
||||
s->iv[4] = e;
|
||||
s->iv[5] = f;
|
||||
s->iv[6] = g;
|
||||
s->iv[7] = h;
|
||||
}
|
||||
|
||||
#if 0 /* Provided for reference only; not used in this code */
|
||||
/*
|
||||
* Initialize the ISAAC RNG with the given seed material. Its size
|
||||
* MUST be a multiple of s->words * sizeof (uint32_t), and may be
|
||||
* stored in the s->mm array.
|
||||
*
|
||||
* This is a generalization of the original ISAAC initialization code
|
||||
* to support larger seed sizes. For seed sizes of 0 and s->words *
|
||||
* sizeof (uint32_t), it is identical.
|
||||
*/
|
||||
void
|
||||
isaac_init (struct isaac_state *s, uint32_t const *seed, size_t seedsize)
|
||||
{
|
||||
static uint32_t const iv[8] =
|
||||
{
|
||||
0x1367df5a, 0x95d90059, 0xc3163e4b, 0x0f421ad8,
|
||||
0xd92a4a78, 0xa51a3c49, 0xc4efea1b, 0x30609119};
|
||||
int i;
|
||||
|
||||
# if 0
|
||||
/* The initialization of iv is a precomputed form of: */
|
||||
for (i = 0; i < 7; i++)
|
||||
iv[i] = 0x9e3779b9; /* the golden ratio */
|
||||
for (i = 0; i < 4; ++i) /* scramble it */
|
||||
mix (iv[0], iv[1], iv[2], iv[3], iv[4], iv[5], iv[6], iv[7]);
|
||||
# endif
|
||||
s->a = s->b = s->c = 0;
|
||||
|
||||
for (i = 0; i < 8; i++)
|
||||
s->iv[i] = iv[i];
|
||||
|
||||
if (seedsize)
|
||||
{
|
||||
/* First pass (as in reference ISAAC code) */
|
||||
isaac_mix (s, seed);
|
||||
/* Second and subsequent passes (extension to ISAAC) */
|
||||
while (seedsize -= s->words * sizeof (uint32_t))
|
||||
{
|
||||
seed += s->words;
|
||||
for (i = 0; i < s->words; i++)
|
||||
s->mm[i] += seed[i];
|
||||
isaac_mix (s, s->mm);
|
||||
}
|
||||
}
|
||||
else
|
||||
{
|
||||
/* The no seed case (as in reference ISAAC code) */
|
||||
for (i = 0; i < s->words; i++)
|
||||
s->mm[i] = 0;
|
||||
}
|
||||
|
||||
/* Final pass */
|
||||
isaac_mix (s, s->mm);
|
||||
}
|
||||
#endif
|
||||
|
||||
/* Start seeding an ISAAC structire */
|
||||
void
|
||||
isaac_seed_start (struct isaac_state *s)
|
||||
{
|
||||
static uint32_t const iv[8] =
|
||||
{
|
||||
0x1367df5a, 0x95d90059, 0xc3163e4b, 0x0f421ad8,
|
||||
0xd92a4a78, 0xa51a3c49, 0xc4efea1b, 0x30609119
|
||||
};
|
||||
int i;
|
||||
|
||||
#if 0
|
||||
/* The initialization of iv is a precomputed form of: */
|
||||
for (i = 0; i < 7; i++)
|
||||
iv[i] = 0x9e3779b9; /* the golden ratio */
|
||||
for (i = 0; i < 4; ++i) /* scramble it */
|
||||
mix (iv[0], iv[1], iv[2], iv[3], iv[4], iv[5], iv[6], iv[7]);
|
||||
#endif
|
||||
for (i = 0; i < 8; i++)
|
||||
s->iv[i] = iv[i];
|
||||
|
||||
/* used to do memset here to clear the state array, but now it's
|
||||
done in isaac_new */
|
||||
|
||||
/* s->c gets used for a data pointer during the seeding phase */
|
||||
s->a = s->b = s->c = 0;
|
||||
}
|
||||
|
||||
/* Add a buffer of seed material */
|
||||
void
|
||||
isaac_seed_data (struct isaac_state *s, void const *buffer, size_t size)
|
||||
{
|
||||
unsigned char const *buf = buffer;
|
||||
unsigned char *p;
|
||||
size_t avail;
|
||||
size_t i;
|
||||
|
||||
avail = s->words - (size_t) s->c; /* s->c is used as a write pointer */
|
||||
|
||||
/* Do any full buffers that are necessary */
|
||||
while (size > avail)
|
||||
{
|
||||
p = (unsigned char *) s->mm + s->c;
|
||||
for (i = 0; i < avail; i++)
|
||||
p[i] ^= buf[i];
|
||||
buf += avail;
|
||||
size -= avail;
|
||||
isaac_mix (s, s->mm);
|
||||
s->c = 0;
|
||||
avail = s->words;
|
||||
}
|
||||
|
||||
/* And the final partial block */
|
||||
p = (unsigned char *) s->mm + s->c;
|
||||
for (i = 0; i < size; i++)
|
||||
p[i] ^= buf[i];
|
||||
s->c = size;
|
||||
}
|
||||
|
||||
|
||||
/* End of seeding phase; get everything ready to produce output. */
|
||||
void
|
||||
isaac_seed_finish (struct isaac_state *s)
|
||||
{
|
||||
isaac_mix (s, s->mm);
|
||||
isaac_mix (s, s->mm);
|
||||
/* Now reinitialize c to start things off right */
|
||||
s->c = 0;
|
||||
}
|
||||
#define ISAAC_SEED(s,x) isaac_seed_data (s, &(x), sizeof (x))
|
||||
|
||||
/*
|
||||
* Get seed material. 16 bytes (128 bits) is plenty, but if we have
|
||||
* /dev/urandom, we get 32 bytes = 256 bits for complete overkill.
|
||||
*/
|
||||
void
|
||||
isaac_seed (struct isaac_state *s)
|
||||
{
|
||||
isaac_seed_start (s);
|
||||
|
||||
{ pid_t t = getpid (); ISAAC_SEED (s, t); }
|
||||
{ pid_t t = getppid (); ISAAC_SEED (s, t); }
|
||||
{ uid_t t = getuid (); ISAAC_SEED (s, t); }
|
||||
{ gid_t t = getgid (); ISAAC_SEED (s, t); }
|
||||
|
||||
{
|
||||
xtime_t t = gethrxtime ();
|
||||
ISAAC_SEED (s, t);
|
||||
}
|
||||
|
||||
{
|
||||
char buf[32];
|
||||
int fd = open ("/dev/urandom", O_RDONLY | O_NOCTTY);
|
||||
if (fd >= 0)
|
||||
{
|
||||
read (fd, buf, 32);
|
||||
close (fd);
|
||||
isaac_seed_data (s, buf, 32);
|
||||
}
|
||||
else
|
||||
{
|
||||
fd = open ("/dev/random", O_RDONLY | O_NONBLOCK | O_NOCTTY);
|
||||
if (fd >= 0)
|
||||
{
|
||||
/* /dev/random is more precious, so use less */
|
||||
read (fd, buf, 16);
|
||||
close (fd);
|
||||
isaac_seed_data (s, buf, 16);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
isaac_seed_finish (s);
|
||||
}
|
||||
|
||||
void
|
||||
irand_init (struct irand_state *r, struct isaac_state *s)
|
||||
{
|
||||
r->numleft = 0;
|
||||
r->s = s;
|
||||
memset (r->r, 0, s->words * sizeof (uint32_t));
|
||||
}
|
||||
|
||||
/*
|
||||
* We take from the end of the block deliberately, so if we need
|
||||
* only a small number of values, we choose the final ones which are
|
||||
* marginally better mixed than the initial ones.
|
||||
*/
|
||||
uint32_t
|
||||
irand32 (struct irand_state *r)
|
||||
{
|
||||
if (!r->numleft)
|
||||
{
|
||||
isaac_refill (r->s, r->r);
|
||||
r->numleft = r->s->words;
|
||||
}
|
||||
return r->r[--r->numleft];
|
||||
}
|
||||
|
||||
/*
|
||||
* Return a uniformly distributed random number between 0 and n,
|
||||
* inclusive. Thus, the result is modulo n+1.
|
||||
*
|
||||
* Theory of operation: as x steps through every possible 32-bit number,
|
||||
* x % n takes each value at least 2^32 / n times (rounded down), but
|
||||
* the values less than 2^32 % n are taken one additional time. Thus,
|
||||
* x % n is not perfectly uniform. To fix this, the values of x less
|
||||
* than 2^32 % n are disallowed, and if the RNG produces one, we ask
|
||||
* for a new value.
|
||||
*/
|
||||
uint32_t
|
||||
irand_mod (struct irand_state *r, uint32_t n)
|
||||
{
|
||||
uint32_t x;
|
||||
uint32_t lim;
|
||||
|
||||
if (!++n)
|
||||
return irand32 (r);
|
||||
|
||||
lim = -n % n; /* == (2**32-n) % n == 2**32 % n */
|
||||
do
|
||||
{
|
||||
x = irand32 (r);
|
||||
}
|
||||
while (x < lim);
|
||||
return x % n;
|
||||
}
|
||||
Reference in New Issue
Block a user