mirror of
https://github.com/matrix-construct/construct
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* librb is no longer a separately configured subproject. * charybdis is now a standalone directory with a binary. * Include path layout now requires a directory ircd/ rb/ etc.
219 lines
4.7 KiB
C
219 lines
4.7 KiB
C
/* $$$: arc4random.c 2005/02/08 robert */
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/* $NetBSD: arc4random.c,v 1.5.2.1 2004/03/26 22:52:50 jmc Exp $ */
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/* $OpenBSD: arc4random.c,v 1.6 2001/06/05 05:05:38 pvalchev Exp $ */
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/*
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* Arc4 random number generator for OpenBSD.
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* Copyright 1996 David Mazieres <dm@lcs.mit.edu>.
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*
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* Modification and redistribution in source and binary forms is
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* permitted provided that due credit is given to the author and the
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* OpenBSD project by leaving this copyright notice intact.
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*/
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/*
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* This code is derived from section 17.1 of Applied Cryptography,
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* second edition, which describes a stream cipher allegedly
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* compatible with RSA Labs "RC4" cipher (the actual description of
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* which is a trade secret). The same algorithm is used as a stream
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* cipher called "arcfour" in Tatu Ylonen's ssh package.
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*
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* Here the stream cipher has been modified always to include the time
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* when initializing the state. That makes it impossible to
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* regenerate the same random sequence twice, so this can't be used
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* for encryption, but will generate good random numbers.
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*
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* RC4 is a registered trademark of RSA Laboratories.
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*/
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#include <rb/rb.h>
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#if !defined(HAVE_OPENSSL) && !defined(HAVE_GNUTLS) && !defined(HAVE_MBEDTLS) && !defined(HAVE_ARC4RANDOM)
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#include "arc4random.h"
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#ifdef HAVE_GETRUSAGE
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#include <sys/resource.h>
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#endif
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struct arc4_stream
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{
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uint8_t i;
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uint8_t j;
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uint8_t s[256];
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};
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static int rs_initialized;
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static struct arc4_stream rs;
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static inline void arc4_init(struct arc4_stream *);
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static inline void arc4_addrandom(struct arc4_stream *, uint8_t *, int);
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static void arc4_stir(struct arc4_stream *);
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static inline uint8_t arc4_getbyte(struct arc4_stream *);
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static inline uint32_t arc4_getword(struct arc4_stream *);
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static inline void
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arc4_init(struct arc4_stream *as)
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{
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int n;
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for(n = 0; n < 256; n++)
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as->s[n] = n;
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as->i = 0;
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as->j = 0;
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}
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static inline void
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arc4_addrandom(struct arc4_stream *as, uint8_t *dat, int datlen)
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{
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int n;
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uint8_t si;
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as->i--;
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for(n = 0; n < 256; n++)
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{
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as->i = (as->i + 1);
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si = as->s[as->i];
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as->j = (as->j + si + dat[n % datlen]);
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as->s[as->i] = as->s[as->j];
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as->s[as->j] = si;
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}
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as->j = as->i;
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}
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static void
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arc4_stir(struct arc4_stream *as)
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{
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struct timeval tv;
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pid_t pid;
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int n;
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#ifdef _WIN32
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HMODULE lib;
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#endif
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/* XXX this doesn't support egd sources or similiar */
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pid = getpid();
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arc4_addrandom(as, (void *)&pid, sizeof(pid));
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rb_gettimeofday(&tv, NULL);
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arc4_addrandom(as, (void *)&tv.tv_sec, sizeof(&tv.tv_sec));
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arc4_addrandom(as, (void *)&tv.tv_usec, sizeof(&tv.tv_usec));
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rb_gettimeofday(&tv, NULL);
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arc4_addrandom(as, (void *)&tv.tv_usec, sizeof(&tv.tv_usec));
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#if defined(HAVE_GETRUSAGE) && RUSAGE_SELF
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{
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struct rusage buf;
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getrusage(RUSAGE_SELF, &buf);
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arc4_addrandom(as, (void *)&buf, sizeof(buf));
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memset(&buf, 0, sizeof(buf))}
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#endif
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#if !defined(_WIN32)
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{
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uint8_t rnd[128];
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int fd;
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fd = open("/dev/urandom", O_RDONLY);
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if(fd != -1)
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{
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read(fd, rnd, sizeof(rnd));
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close(fd);
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arc4_addrandom(as, (void *)rnd, sizeof(rnd));
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memset(&rnd, 0, sizeof(rnd));
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}
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}
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#else
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{
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LARGE_INTEGER performanceCount;
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if(QueryPerformanceCounter(&performanceCount))
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{
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arc4_addrandom(as, (void *)&performanceCount, sizeof(performanceCount));
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}
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lib = LoadLibrary("ADVAPI32.DLL");
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if(lib)
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{
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uint8_t rnd[128];
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BOOLEAN(APIENTRY * pfn) (void *, ULONG) =
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(BOOLEAN(APIENTRY *) (void *, ULONG))GetProcAddress(lib,
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"SystemFunction036");
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if(pfn)
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{
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if(pfn(rnd, sizeof(rnd)) == TRUE)
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arc4_addrandom(as, (void *)rnd, sizeof(rnd));
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memset(&rnd, 0, sizeof(rnd));
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}
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}
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}
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#endif
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/*
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* Throw away the first N words of output, as suggested in the
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* paper "Weaknesses in the Key Scheduling Algorithm of RC4"
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* by Fluher, Mantin, and Shamir.
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* http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
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* N = 256 in our case.
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*/
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for(n = 0; n < 256 * 4; n++)
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arc4_getbyte(as);
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}
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static inline uint8_t
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arc4_getbyte(struct arc4_stream *as)
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{
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uint8_t si, sj;
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as->i = (as->i + 1);
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si = as->s[as->i];
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as->j = (as->j + si);
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sj = as->s[as->j];
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as->s[as->i] = sj;
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as->s[as->j] = si;
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return (as->s[(si + sj) & 0xff]);
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}
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static inline uint32_t
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arc4_getword(struct arc4_stream *as)
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{
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uint32_t val;
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val = arc4_getbyte(as) << 24;
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val |= arc4_getbyte(as) << 16;
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val |= arc4_getbyte(as) << 8;
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val |= arc4_getbyte(as);
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return val;
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}
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void
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arc4random_stir(void)
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{
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if(!rs_initialized)
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{
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arc4_init(&rs);
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rs_initialized = 1;
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}
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arc4_stir(&rs);
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}
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void
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arc4random_addrandom(uint8_t *dat, int datlen)
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{
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if(!rs_initialized)
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arc4random_stir();
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arc4_addrandom(&rs, dat, datlen);
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}
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uint32_t
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arc4random(void)
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{
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if(!rs_initialized)
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arc4random_stir();
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return arc4_getword(&rs);
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}
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#endif
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