From Devin Heitmueller:

[obnox/wireshark/wip.git] / crypt-rc4.c

diff --git a/crypt-rc4.c b/crypt-rc4.c
new file mode 100644 (file)
index 0000000..73d08d4
--- /dev/null
+++ b/crypt-rc4.c
@@ -0,0 +1,81 @@
+/* 
+   Unix SMB/CIFS implementation.
+
+   a partial implementation of RC4 designed for use in the 
+   SMB authentication protocol
+
+   Copyright (C) Andrew Tridgell 1998
+
+   $Id: crypt-rc4.c,v 1.1 2002/12/03 00:37:27 guy Exp $
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+#include <glib.h>
+
+/* Perform RC4 on a block of data using specified key.  "data" is a pointer
+   to the block to be processed.  Output is written to same memory as input,
+   so caller may need to make a copy before calling this function, since
+   the input will be overwritten.  "val" specifies length of data buffer.
+   "key" is assumed to be a 16 octets in length
+   
+   Taken from Samba source code.  In the long term, it might be nice to have
+   the input and output buffer differ, have a length specifier for the key,
+   and separate the initialization function from the process function (as is
+   done with the Alleged-RC4 implementation).
+*/
+
+void crypt_rc4( unsigned char *data, const unsigned char *key, int val)
+{
+  unsigned char s_box[256];
+  unsigned char index_i = 0;
+  unsigned char index_j = 0;
+  unsigned char j = 0;
+  int ind;
+
+  for (ind = 0; ind < 256; ind++)
+  {
+    s_box[ind] = (unsigned char)ind;
+  }
+
+  for( ind = 0; ind < 256; ind++)
+  {
+     unsigned char tc;
+
+     j += (s_box[ind] + key[ind%16]);
+
+     tc = s_box[ind];
+     s_box[ind] = s_box[j];
+     s_box[j] = tc;
+  }
+  for( ind = 0; ind < val; ind++)
+  {
+    unsigned char tc;
+    unsigned char t;
+
+    index_i++;
+    index_j += s_box[index_i];
+
+    tc = s_box[index_i];
+    s_box[index_i] = s_box[index_j];
+    s_box[index_j] = tc;
+
+    t = s_box[index_i] + s_box[index_j];
+    data[ind] = data[ind] ^ s_box[t];
+  }
+}