00001 // NullCipher - the null encryption method 00002 // 00003 // Copyright (C) 1996 by Jef Poskanzer <jef@acme.com>. All rights reserved. 00004 // 00005 // Redistribution and use in source and binary forms, with or without 00006 // modification, are permitted provided that the following conditions 00007 // are met: 00008 // 1. Redistributions of source code must retain the above copyright 00009 // notice, this list of conditions and the following disclaimer. 00010 // 2. Redistributions in binary form must reproduce the above copyright 00011 // notice, this list of conditions and the following disclaimer in the 00012 // documentation and/or other materials provided with the distribution. 00013 // 00014 // THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 00015 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 00016 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 00017 // ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 00018 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 00019 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 00020 // OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 00021 // HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 00022 // LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 00023 // OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 00024 // SUCH DAMAGE. 00025 // 00026 // Visit the ACME Labs Java page for up-to-date versions of this and other 00027 // fine Java utilities: http://www.acme.com/java/ 00028 00029 package Acme.Crypto; 00030 00031 import java.io.*; 00032 00034 // <P> 00035 // This is a block cipher that just copies input to output, unmodified. 00036 // It's mostly for testing. However, using the null cipher in CBC mode, 00037 // for example via EncryptedOutputStream and EncryptedInputStream, turns 00038 // out to hash things up enough to protect against casual inspection. 00039 // There may be applications where this is appropriate. 00040 // <P> 00041 // <A HREF="/resources/classes/Acme/Crypto/NullCipher.java">Fetch the software.</A><BR> 00042 // <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A> 00043 // <P> 00044 // @see EncryptedOutputStream 00045 // @see EncryptedInputStream 00046 00047 public class NullCipher extends BlockCipher 00048 { 00049 00051 public NullCipher() 00052 { 00053 super( 0, 8 ); 00054 } 00055 00056 00057 // Key routines. 00058 00060 public void setKey( byte[] key ) 00061 { 00062 throw new InternalError( "NullCipher does not need a key" ); 00063 } 00064 00065 00066 // Block encryption routines. 00067 00069 public void encrypt( byte[] clearText, int clearOff, byte[] cipherText, int cipherOff ) 00070 { 00071 copyBlock( clearText, clearOff, cipherText, cipherOff, blockSize ); 00072 } 00073 00075 public void decrypt( byte[] cipherText, int cipherOff, byte[] clearText, int clearOff ) 00076 { 00077 copyBlock( cipherText, cipherOff, clearText, clearOff, blockSize ); 00078 } 00079 00080 }