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//******************************************************************************
//
// File: Encrypt.java
// Package: edu.rit.clu.keysearch
// Unit: Class edu.rit.clu.keysearch.Encrypt
//
// This Java source file is copyright (C) 2007 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ 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 3 of the License, or (at your option) any later version.
//
// PJ 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.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************
package edu.rit.clu.keysearch;
import edu.rit.crypto.blockcipher.AES256Cipher;
import edu.rit.util.Hex;
/**
* Class Encrypt prepares input for the AES partial key search programs. The
* program's command line arguments are a message string to encrypt, the
* encryption key, and <I>n</I>, the number of key bits to search for. The
* program prints on the standard output the plaintext (128-bit hexadecimal
* number), the ciphertext (128-bit hexadecimal number), the partial key with
* the <I>n</I> least significant bits set to 0 (256-bit hexadecimal number),
* and <I>n</I>, the number of key bits to search for.
* <P>
* Usage: java edu.rit.clu.keysearch.Encrypt <I>message</I> <I>key</I> <I>n</I>
* <BR><I>message</I> = Message string to encrypt
* <BR><I>key</I> = Encryption key (256-bit hexadecimal number)
* <BR><I>n</I> = Number of key bits to search for
*
* @author Alan Kaminsky
* @version 16-Jan-2007
*/
public class Encrypt
{
// Prevent construction.
private Encrypt()
{
}
// Main program.
/**
* Encrypt main program.
*/
public static void main
(String[] args)
throws Exception
{
// Parse command line arguments.
if (args.length != 3) usage();
String message = args[0];
byte[] key = Hex.toByteArray (args[1]);
int n = Integer.parseInt (args[2]);
// Set up plaintext block.
byte[] msg = message.getBytes();
byte[] block = new byte [16];
System.arraycopy (msg, 0, block, 0, Math.min (msg.length, 16));
System.out.println (Hex.toString (block));
// Encrypt plaintext.
AES256Cipher cipher = new AES256Cipher (key);
cipher.encrypt (block);
System.out.println (Hex.toString (block));
// Wipe out n least significant bits of the key.
int off = 31;
int len = n;
while (len >= 8)
{
key[off] = (byte) 0;
-- off;
len -= 8;
}
key[off] &= mask[len];
System.out.println (Hex.toString (key));
System.out.println (n);
}
private static final int[] mask = new int[]
{0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80};
// Hidden operations.
/**
* Print a usage message and exit.
*/
private static void usage()
{
System.err.println ("Usage: java edu.rit.clu.keysearch.Encrypt <message> <key> <n>");
System.err.println ("<message> = Message string to encrypt");
System.err.println ("<key> = Encryption key (256-bit hexadecimal number)");
System.err.println ("<n> = Number of key bits to search for");
System.exit (0);
}
}
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