/* 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 3 of the License, 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, see <http://www.gnu.org/licenses/>. 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); }

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