00001 // StreamCipher - a stream encryption template 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 // <A HREF="/resources/classes/Acme/Crypto/StreamCipher.java">Fetch the software.</A><BR> 00036 // <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A> 00037 // <P> 00038 // @see Cipher 00039 // @see BlockCipher 00040 // @see EncryptedOutputStream 00041 // @see EncryptedInputStream 00042 // @see Rc4Cipher 00043 00044 public abstract class StreamCipher extends Cipher 00045 { 00046 00048 public StreamCipher( int keySize ) 00049 { 00050 super( keySize ); 00051 } 00052 00054 public abstract byte encrypt( byte clearText ); 00055 00057 public abstract byte decrypt( byte cipherText ); 00058 00060 public void encrypt( byte[] clearText, byte[] cipherText ) 00061 { 00062 encrypt( clearText, 0, cipherText, 0, clearText.length ); 00063 } 00064 00066 public void decrypt( byte[] cipherText, byte[] clearText ) 00067 { 00068 decrypt( cipherText, 0, clearText, 0, cipherText.length ); 00069 } 00070 00072 // The default implementation just calls encrypt(byte) repeatedly. 00073 // This can be overridden for speed. 00074 public void encrypt( byte[] clearText, int clearOff, byte[] cipherText, int cipherOff, int len ) 00075 { 00076 for ( int i = 0; i < len; ++i ) 00077 cipherText[cipherOff + i] = encrypt( clearText[clearOff + i] ); 00078 } 00079 00081 // The default implementation just calls decrypt(byte) repeatedly. 00082 // This can be overridden for speed. 00083 public void decrypt( byte[] cipherText, int cipherOff, byte[] clearText, int clearOff, int len ) 00084 { 00085 for ( int i = 0; i < len; ++i ) 00086 clearText[clearOff + i] = decrypt( cipherText[cipherOff + i] ); 00087 } 00088 00089 }