1 files changed, 176 insertions, 0 deletions

diff --git a/src/lib/libc/crypt/arc4random.c b/src/lib/libc/crypt/arc4random.c
new file mode 100644
index 0000000000..5279c21518
--- /dev/null
+++ b/src/lib/libc/crypt/arc4random.c
@@ -0,0 +1,176 @@
+/*      $OpenBSD: arc4random.c,v 1.3 1998/03/22 19:01:16 niklas 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 <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/time.h>
+
+#ifdef __GNUC__
+#define inline __inline
+#else                           /* !__GNUC__ */
+#define inline
+#endif                          /* !__GNUC__ */
+
+struct arc4_stream {
+        u_int8_t i;
+        u_int8_t j;
+        u_int8_t s[256];
+};
+
+int     rs_initialized;
+static struct arc4_stream rs;
+
+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;
+                u_int8_t rnd[128 - sizeof(struct timeval)];
+        }       rdat;
+
+        gettimeofday(&rdat.tv, NULL);
+        fd = open("/dev/arandom", O_RDONLY);
+        if (fd >= 0) {
+                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_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