--- /dev/null
+/*
+ * 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 <sys/cdefs.h>
+__FBSDID("$FreeBSD: src/lib/libc/gen/arc4random.c,v 1.10 2004/03/24 14:44:57 green Exp $");
+
+#include "namespace.h"
+#include <sys/types.h>
+#include <sys/time.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pthread.h>
+
+#include "libc_private.h"
+#include "un-namespace.h"
+
+struct arc4_stream {
+ u_int8_t i;
+ u_int8_t j;
+ u_int8_t s[256];
+};
+
+static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
+
+#define RANDOMDEV "/dev/urandom"
+#define THREAD_LOCK() \
+ do { \
+ if (__isthreaded) \
+ _pthread_mutex_lock(&arc4random_mtx); \
+ } while (0)
+
+#define THREAD_UNLOCK() \
+ do { \
+ if (__isthreaded) \
+ _pthread_mutex_unlock(&arc4random_mtx); \
+ } while (0)
+
+static struct arc4_stream rs;
+static int rs_initialized;
+static int rs_stired;
+
+static inline u_int8_t arc4_getbyte(struct arc4_stream *);
+static void arc4_stir(struct arc4_stream *);
+
+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, n;
+ 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(RANDOMDEV, 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));
+
+ /*
+ * Throw away the first N bytes of output, as suggested in the
+ * paper "Weaknesses in the Key Scheduling Algorithm of RC4"
+ * by Fluher, Mantin, and Shamir. N=1024 is based on
+ * suggestions in the paper "(Not So) Random Shuffles of RC4"
+ * by Ilya Mironov.
+ */
+ for (n = 0; n < 1024; n++)
+ arc4_getbyte(as);
+}
+
+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);
+}
+
+static void
+arc4_check_init(void)
+{
+ if (!rs_initialized) {
+ arc4_init(&rs);
+ rs_initialized = 1;
+ }
+}
+
+static void
+arc4_check_stir(void)
+{
+ if (!rs_stired) {
+ arc4_stir(&rs);
+ rs_stired = 1;
+ }
+}
+
+void
+arc4random_stir()
+{
+ THREAD_LOCK();
+ arc4_check_init();
+ arc4_stir(&rs);
+ THREAD_UNLOCK();
+}
+
+void
+arc4random_addrandom(dat, datlen)
+ u_char *dat;
+ int datlen;
+{
+ THREAD_LOCK();
+ arc4_check_init();
+ arc4_check_stir();
+ arc4_addrandom(&rs, dat, datlen);
+ THREAD_UNLOCK();
+}
+
+u_int32_t
+arc4random()
+{
+ u_int32_t rnd;
+
+ THREAD_LOCK();
+ arc4_check_init();
+ arc4_check_stir();
+ rnd = arc4_getword(&rs);
+ THREAD_UNLOCK();
+
+ return (rnd);
+}
+
+#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
projects / apple / libc.git / blobdiff