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Diffstat (limited to 'lib/rand-isaac.c')
| -rw-r--r-- | lib/rand-isaac.c | 301 |
1 files changed, 301 insertions, 0 deletions
diff --git a/lib/rand-isaac.c b/lib/rand-isaac.c new file mode 100644 index 0000000..cfdc643 --- /dev/null +++ b/lib/rand-isaac.c @@ -0,0 +1,301 @@ +/* Bob Jenkins's cryptographic random number generator, ISAAC. + + Copyright (C) 1999-2006 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. */ + +/* + * -------------------------------------------------------------------- + * We need a source of random numbers for some data. + * 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. + * -------------------------------------------------------------------- + */ +#include <config.h> + +#include "rand-isaac.h" + +#include <string.h> +#include <unistd.h> + +#include "gethrxtime.h" + + +/* This index operation is more efficient on many processors */ +#define ind(mm, x) \ + (* (uint32_t *) ((char *) (mm) \ + + ((x) & (ISAAC_WORDS - 1) * sizeof (uint32_t)))) + +/* + * The central step. This uses two temporaries, x and y. mm is the + * whole state array, while m is a pointer to the current word. off is + * the offset from m to the word ISAAC_WORDS/2 words away in the mm array, + * i.e. +/- ISAAC_WORDS/2. + */ +#define isaac_step(mix, a, b, mm, m, off, r) \ +( \ + a = ((a) ^ (mix)) + (m)[off], \ + x = *(m), \ + *(m) = y = ind (mm, x) + (a) + (b), \ + *(r) = b = ind (mm, (y) >> ISAAC_LOG) + x \ +) + +/* Use and update *S to generate random data to fill R. */ +void +isaac_refill (struct isaac_state *s, uint32_t r[ISAAC_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 */ + + a = s->a; + b = s->b + (++s->c); + + do + { + isaac_step (a << 13, a, b, s->mm, m, ISAAC_WORDS / 2, r); + isaac_step (a >> 6, a, b, s->mm, m + 1, ISAAC_WORDS / 2, r + 1); + isaac_step (a << 2, a, b, s->mm, m + 2, ISAAC_WORDS / 2, r + 2); + isaac_step (a >> 16, a, b, s->mm, m + 3, ISAAC_WORDS / 2, r + 3); + r += 4; + } + while ((m += 4) < s->mm + ISAAC_WORDS / 2); + do + { + isaac_step (a << 13, a, b, s->mm, m, -ISAAC_WORDS / 2, r); + isaac_step (a >> 6, a, b, s->mm, m + 1, -ISAAC_WORDS / 2, r + 1); + isaac_step (a << 2, a, b, s->mm, m + 2, -ISAAC_WORDS / 2, r + 2); + isaac_step (a >> 16, a, b, s->mm, m + 3, -ISAAC_WORDS / 2, r + 3); + r += 4; + } + while ((m += 4) < s->mm + ISAAC_WORDS); + 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. */ +static void +isaac_mix (struct isaac_state *s, uint32_t const seed[/* ISAAC_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]; + + for (i = 0; i < ISAAC_WORDS; 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 ISAAC_BYTES, 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 ISAAC_BYTES, + * it is identical. + */ +static 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 -= ISAAC_BYTES) + { + seed += ISAAC_WORDS; + for (i = 0; i < ISAAC_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 < ISAAC_WORDS; i++) + s->mm[i] = 0; + } + + /* Final pass */ + isaac_mix (s, s->mm); +} +#endif + +/* Initialize *S to a somewhat-random value. */ +static void +isaac_seed_start (struct isaac_state *s) +{ + static uint32_t const iv[8] = + { + 0x1367df5a, 0x95d90059, 0xc3163e4b, 0x0f421ad8, + 0xd92a4a78, 0xa51a3c49, 0xc4efea1b, 0x30609119 + }; + +#if 0 + /* The initialization of iv is a precomputed form of: */ + int i; + 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 + + memset (s->mm, 0, sizeof s->mm); + memcpy (s->iv, iv, sizeof s->iv); + + /* 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. */ +static 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 = sizeof s->mm - 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 = sizeof s->mm; + } + + /* 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. */ +static 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)) + +/* Initialize *S to a somewhat-random value; this starts seeding, + seeds with somewhat-random data, and finishes seeding. */ +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); + } + + isaac_seed_finish (s); +} |