Cipher.java

00001 // Cipher - an 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/Cipher.java">Fetch the software.</A><BR>
00036 // <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>
00037 // <P>
00038 // @see StreamCipher
00039 // @see BlockCipher
00040 // @see EncryptedOutputStream
00041 // @see EncryptedInputStream
00042 
00043 public abstract class Cipher extends CryptoUtils
00044     {
00045 
00047     public Cipher( int keySize )
00048         {
00049         this.keySize = keySize;
00050         }
00051 
00053     // also use 0.
00054     public int keySize;
00055 
00057     public int keySize()
00058         {
00059         return keySize;
00060         }
00061 
00063     public abstract void setKey( byte[] key );
00064 
00065 
00066     // Utility routines.
00067 
00069     public void setKey( String keyStr )
00070         {
00071         setKey( makeKey( keyStr ) );
00072         }
00073 
00075     public byte[] makeKey( String keyStr )
00076         {
00077         byte[] key;
00078         if ( keySize == 0 )
00079             key = new byte[keyStr.length()];
00080         else
00081             key = new byte[keySize];
00082         int i, j;
00083 
00084         for ( j = 0; j < key.length; ++j )
00085             key[j] = 0;
00086 
00087         for ( i = 0, j = 0; i < keyStr.length(); ++i, j = (j+1) % key.length )
00088             key[j] ^= (byte) keyStr.charAt( i );
00089 
00090         return key;
00091         }
00092 
00093     }

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