/* * Copyright (c) 2003 Apple Computer, Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved. * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this * file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_LICENSE_HEADER_END@ */ /* $FreeBSD: src/lib/libc/gen/arc4random.c,v 1.4 2000/01/27 23:06:13 jasone Exp $ */ /* * Arc4 random number generator for OpenBSD. * Copyright 1996 David Mazieres <dm@lcs.mit.edu>. * * Modification and redistribution in source and binary forms is * permitted provided that due credit is given to the author and the * OpenBSD project (for instance by leaving this copyright notice * intact). */ /* * This code is derived from section 17.1 of Applied Cryptography, * second edition, which describes a stream cipher allegedly * compatible with RSA Labs "RC4" cipher (the actual description of * which is a trade secret). The same algorithm is used as a stream * cipher called "arcfour" in Tatu Ylonen's ssh package. * * Here the stream cipher has been modified always to include the time * when initializing the state. That makes it impossible to * regenerate the same random sequence twice, so this can't be used * for encryption, but will generate good random numbers. * * RC4 is a registered trademark of RSA Laboratories. */ #include <stdlib.h> #include <fcntl.h> #include <unistd.h> #include <sys/types.h> #include <sys/time.h> struct arc4_stream { u_int8_t i; u_int8_t j; u_int8_t s[256]; }; static int rs_initialized; static struct arc4_stream *rs = NULL; static inline void arc4_init(as) struct arc4_stream *as; { int n; for (n = 0; n < 256; n++) as->s[n] = n; as->i = 0; as->j = 0; } static inline void arc4_addrandom(as, dat, datlen) struct arc4_stream *as; u_char *dat; int datlen; { int n; u_int8_t si; as->i--; for (n = 0; n < 256; n++) { as->i = (as->i + 1); si = as->s[as->i]; as->j = (as->j + si + dat[n % datlen]); as->s[as->i] = as->s[as->j]; as->s[as->j] = si; } } static void arc4_stir(as) struct arc4_stream *as; { int fd; struct { struct timeval tv; pid_t pid; u_int8_t rnd[128 - sizeof(struct timeval) - sizeof(pid_t)]; } rdat; gettimeofday(&rdat.tv, NULL); rdat.pid = getpid(); fd = open("/dev/urandom", O_RDONLY, 0); if (fd >= 0) { (void) read(fd, rdat.rnd, sizeof(rdat.rnd)); close(fd); } /* fd < 0? Ah, what the heck. We'll just take whatever was on the * stack... */ arc4_addrandom(as, (void *) &rdat, sizeof(rdat)); } static inline u_int8_t arc4_getbyte(as) struct arc4_stream *as; { u_int8_t si, sj; as->i = (as->i + 1); si = as->s[as->i]; as->j = (as->j + si); sj = as->s[as->j]; as->s[as->i] = sj; as->s[as->j] = si; return (as->s[(si + sj) & 0xff]); } static inline u_int32_t arc4_getword(as) struct arc4_stream *as; { u_int32_t val; val = arc4_getbyte(as) << 24; val |= arc4_getbyte(as) << 16; val |= arc4_getbyte(as) << 8; val |= arc4_getbyte(as); return val; } void arc4random_stir() { if ( rs == NULL ) { rs = malloc( sizeof(struct arc4_stream) ); if( rs == NULL ) return ; /* Hmmm. */ } if (!rs_initialized) { arc4_init(rs); rs_initialized = 1; } arc4_stir(rs); } void arc4random_addrandom(dat, datlen) u_char *dat; int datlen; { if (!rs_initialized) arc4random_stir(); arc4_addrandom(rs, dat, datlen); } u_int32_t arc4random() { if (!rs_initialized) arc4random_stir(); return arc4_getword(rs); } #if 0 /*-------- Test code for i386 --------*/ #include <stdio.h> #include <machine/pctr.h> int main(int argc, char **argv) { const int iter = 1000000; int i; pctrval v; v = rdtsc(); for (i = 0; i < iter; i++) arc4random(); v = rdtsc() - v; v /= iter; printf("%qd cycles\n", v); } #endif