1 files changed, 182 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..5b376488ec
--- /dev/null
+++ b/src/lib/libc/crypt/arc4random.c
@@ -0,0 +1,182 @@
+/*      $OpenBSD: arc4random.c,v 1.10 2003/11/26 21:40:08 djm 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 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/param.h>
+#include <sys/time.h>
+#include <sys/sysctl.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];
+};
+
+static int rs_initialized;
+static struct arc4_stream rs;
+static pid_t arc4_stir_pid;
+
+static inline u_int8_t arc4_getbyte(struct arc4_stream *);
+
+static inline void
+arc4_init(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(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;
+        }
+        as->j = as->i;
+}
+
+static void
+arc4_stir(struct arc4_stream *as)
+{
+        int     i, mib[2];
+        size_t  len;
+        struct {
+                struct timeval tv;
+                u_int rnd[(128 - sizeof(struct timeval)) / sizeof(u_int)];
+        }       rdat;
+
+        gettimeofday(&rdat.tv, NULL);
+        mib[0] = CTL_KERN;
+        mib[1] = KERN_ARND;
+
+        for (i = 0; i < sizeof(rdat.rnd) / sizeof(u_int); i ++) {
+                len = sizeof(u_int);
+                if (sysctl(mib, 2, &rdat.rnd[i], &len, NULL, 0) == -1)
+                        break;
+        }
+
+        arc4_stir_pid = getpid();
+        arc4_addrandom(as, (void *) &rdat, sizeof(rdat));
+
+        /*
+         * Discard early keystream, as per recommendations in:
+         * http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
+         */
+        for (i = 0; i < 256; i++)
+                (void) arc4_getbyte(as);
+}
+
+static inline u_int8_t
+arc4_getbyte(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(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(void)
+{
+        if (!rs_initialized) {
+                arc4_init(&rs);
+                rs_initialized = 1;
+        }
+        arc4_stir(&rs);
+}
+
+void
+arc4random_addrandom(u_char *dat, int datlen)
+{
+        if (!rs_initialized)
+                arc4random_stir();
+        arc4_addrandom(&rs, dat, datlen);
+}
+
+u_int32_t
+arc4random(void)
+{
+        if (!rs_initialized || arc4_stir_pid != getpid())
+                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