- deraadt@cvs.openbsd.org 2005/02/25 13:29:30

[openssh.git] / openbsd-compat / bsd-arc4random.c

diff --git a/openbsd-compat/bsd-arc4random.c b/openbsd-compat/bsd-arc4random.c
index 25a559be006bf2d55b800b5783926b0f2895e941..d45fb182a6fb9725bb8794d7f7b947a8bf2f6c7a 100644 (file)
--- a/openbsd-compat/bsd-arc4random.c
+++ b/openbsd-compat/bsd-arc4random.c
@@ -1,31 +1,27 @@
 /*
- * Copyright (c) 1999-2000 Damien Miller.  All rights reserved.
+ * Copyright (c) 1999,2000,2004 Damien Miller <djm@mindrot.org>
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
  *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
 #include "includes.h"
-#include "log.h"
 
-RCSID("$Id$");
+#include <sys/types.h>
+
+#include <string.h>
+#include <stdarg.h>
+
+#include "log.h"
 
 #ifndef HAVE_ARC4RANDOM
 
@@ -42,7 +38,8 @@ RCSID("$Id$");
 static int rc4_ready = 0;
 static RC4_KEY rc4;
 
-unsigned int arc4random(void)
+unsigned int
+arc4random(void)
 {
        unsigned int r = 0;
        static int first_time = 1;
@@ -61,15 +58,25 @@ unsigned int arc4random(void)
        return(r);
 }
 
-void arc4random_stir(void)
+void
+arc4random_stir(void)
 {
        unsigned char rand_buf[SEED_SIZE];
+       int i;
 
        memset(&rc4, 0, sizeof(rc4));
-       if (!RAND_bytes(rand_buf, sizeof(rand_buf)))
+       if (RAND_bytes(rand_buf, sizeof(rand_buf)) <= 0)
                fatal("Couldn't obtain random bytes (error %ld)",
                    ERR_get_error());
        RC4_set_key(&rc4, sizeof(rand_buf), rand_buf);
+
+       /*
+        * 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 += sizeof(rand_buf))
+               RC4(&rc4, sizeof(rand_buf), rand_buf, rand_buf);
+
        memset(rand_buf, 0, sizeof(rand_buf));
 
        rc4_ready = REKEY_BYTES;