[src/trunk]: src/sys/lib/libkern have arc4random(9).

[itojun <itojun%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/06cf3617b370
branches:  trunk
changeset: 531875:06cf3617b370
user:      itojun <itojun%NetBSD.org@localhost>
date:      Tue May 28 10:09:24 2002 +0000

description:
have arc4random(9).

diffstat:

 sys/lib/libkern/Makefile     |    4 +-
 sys/lib/libkern/arc4random.c |  141 +++++++++++++++++++++++++++++++++++++++++++
 sys/lib/libkern/libkern.h    |    3 +-
 3 files changed, 145 insertions(+), 3 deletions(-)

diffs (180 lines):

diff -r edff6d13a257 -r 06cf3617b370 sys/lib/libkern/Makefile
--- a/sys/lib/libkern/Makefile  Tue May 28 10:07:51 2002 +0000
+++ b/sys/lib/libkern/Makefile  Tue May 28 10:09:24 2002 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: Makefile,v 1.63 2001/12/12 01:50:04 tv Exp $
+#      $NetBSD: Makefile,v 1.64 2002/05/28 10:09:24 itojun Exp $
 
 LIB=   kern
 NOPIC= # defined
@@ -37,7 +37,7 @@
 
 # Other stuff
 SRCS+= __cmsg_alignbytes.c inet_addr.c intoa.c md4c.c md5c.c sha1.c pmatch.c
-SRCS+= _que.c
+SRCS+= _que.c arc4random.c
 
 # Files to clean up
 CLEANFILES+= lib${LIB}.o lib${LIB}.po
diff -r edff6d13a257 -r 06cf3617b370 sys/lib/libkern/arc4random.c
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/sys/lib/libkern/arc4random.c      Tue May 28 10:09:24 2002 +0000
@@ -0,0 +1,141 @@
+/*     $NetBSD: arc4random.c,v 1.1 2002/05/28 10:09:24 itojun Exp $    */
+
+/*-
+ * THE BEER-WARE LICENSE
+ *
+ * <dan%FreeBSD.ORG@localhost> wrote this file.  As long as you retain this notice you
+ * can do whatever you want with this stuff.  If we meet some day, and you
+ * think this stuff is worth it, you can buy me a beer in return.
+ *
+ * Dan Moschuk
+ *
+ * $FreeBSD: src/sys/libkern/arc4random.c,v 1.9 2001/08/30 12:30:58 bde Exp $
+ */
+
+#include <sys/types.h>
+#include <sys/time.h>
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/systm.h>
+
+#include <lib/libkern/libkern.h>
+
+#if NRND > 0
+#include <dev/rnd.h>
+#endif
+
+#define        ARC4_MAXRUNS 16384
+#define        ARC4_RESEED_SECONDS 300
+#define        ARC4_KEYBYTES 32 /* 256 bit key */
+
+static u_int8_t arc4_i, arc4_j;
+static int arc4_initialized = 0;
+static int arc4_numruns = 0;
+static u_int8_t arc4_sbox[256];
+static struct timeval arc4_tv_nextreseed;
+
+static u_int8_t arc4_randbyte(void);
+
+static __inline void
+arc4_swap(u_int8_t *a, u_int8_t *b)
+{
+       u_int8_t c;
+
+       c = *a;
+       *a = *b;
+       *b = c;
+}      
+
+/*
+ * Stir our S-box.
+ */
+static void
+arc4_randomstir(void)
+{
+       u_int8_t key[256];
+       int r, n;
+
+#if NRND > 0
+       r = rnd_extract_data(key, ARC4_KEYBYTES, RND_EXTRACT_ANY);
+#else
+       r = 0;  /*XXX*/
+#endif
+       /* If r == 0 || -1, just use what was on the stack. */
+       if (r > 0) {
+               for (n = r; n < sizeof(key); n++)
+                       key[n] = key[n % r];
+       }
+
+       for (n = 0; n < 256; n++) {
+               arc4_j = (arc4_j + arc4_sbox[n] + key[n]) % 256;
+               arc4_swap(&arc4_sbox[n], &arc4_sbox[arc4_j]);
+       }
+
+       /* Reset for next reseed cycle. */
+       arc4_tv_nextreseed = mono_time;
+       arc4_tv_nextreseed.tv_sec += ARC4_RESEED_SECONDS;
+       arc4_numruns = 0;
+}
+
+/*
+ * Initialize our S-box to its beginning defaults.
+ */
+static void
+arc4_init(void)
+{
+       int n;
+
+       arc4_i = arc4_j = 0;
+       for (n = 0; n < 256; n++)
+               arc4_sbox[n] = (u_int8_t) n;
+
+       arc4_randomstir();
+       arc4_initialized = 1;
+
+       /*
+        * Throw away the first N words of output, as suggested in the
+        * paper "Weaknesses in the Key Scheduling Algorithm of RC4"
+        * by Fluher, Mantin, and Shamir.  (N = 256 in our case.)
+        */
+       for (n = 0; n < 256 * 4; n++)
+               arc4_randbyte();
+}
+
+/*
+ * Generate a random byte.
+ */
+static u_int8_t
+arc4_randbyte(void)
+{
+       u_int8_t arc4_t;
+
+       arc4_i = (arc4_i + 1) % 256;
+       arc4_j = (arc4_j + arc4_sbox[arc4_i]) % 256;
+
+       arc4_swap(&arc4_sbox[arc4_i], &arc4_sbox[arc4_j]);
+
+       arc4_t = (arc4_sbox[arc4_i] + arc4_sbox[arc4_j]) % 256;
+       return arc4_sbox[arc4_t];
+}
+
+u_int32_t
+arc4random(void)
+{
+       u_int32_t ret;
+
+       /* Initialize array if needed. */
+       if (!arc4_initialized)
+               arc4_init();
+
+       if ((++arc4_numruns > ARC4_MAXRUNS) || 
+           (mono_time.tv_sec > arc4_tv_nextreseed.tv_sec)) {
+               arc4_randomstir();
+       }
+
+       ret = arc4_randbyte();
+       ret |= arc4_randbyte() << 8;
+       ret |= arc4_randbyte() << 16;
+       ret |= arc4_randbyte() << 24;
+
+       return ret;
+}
diff -r edff6d13a257 -r 06cf3617b370 sys/lib/libkern/libkern.h
--- a/sys/lib/libkern/libkern.h Tue May 28 10:07:51 2002 +0000
+++ b/sys/lib/libkern/libkern.h Tue May 28 10:09:24 2002 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: libkern.h,v 1.39 2001/12/28 07:37:06 thorpej Exp $     */
+/*     $NetBSD: libkern.h,v 1.40 2002/05/28 10:09:24 itojun Exp $      */
 
 /*-
  * Copyright (c) 1992, 1993
@@ -298,6 +298,7 @@
 void   *memchr __P((const void *, int, size_t));
 void   *memmove __P((void *, const void *, size_t));
 int     pmatch __P((const char *, const char *, const char **));
+u_int32_t arc4random __P((void));
 u_long  random __P((void));
 int     scanc __P((u_int, const u_char *, const u_char *, int));
 int     skpc __P((int, size_t, u_char *));