KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > Acme > Crypto > StreamCipher


1 // StreamCipher - a stream encryption template
2 //
3 // Copyright (C) 1996 by Jef Poskanzer <jef@acme.com>. All rights reserved.
4 //
5 // Redistribution and use in source and binary forms, with or without
6 // modification, are permitted provided that the following conditions
7 // are met:
8 // 1. Redistributions of source code must retain the above copyright
9 // notice, this list of conditions and the following disclaimer.
10 // 2. Redistributions in binary form must reproduce the above copyright
11 // notice, this list of conditions and the following disclaimer in the
12 // documentation and/or other materials provided with the distribution.
13 //
14 // THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 // ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 // OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 // HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 // LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 // OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 // SUCH DAMAGE.
25 //
26 // Visit the ACME Labs Java page for up-to-date versions of this and other
27 // fine Java utilities: http://www.acme.com/java/
28
29 package Acme.Crypto;
30
31 import java.io.*;
32
33 /// A stream encryption template.
34 // <P>
35 // <A HREF="../../../resources/classes/Acme/Crypto/StreamCipher.java">Fetch the software.</A><BR>
36 // <A HREF="../../../resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>
37 // <P>
38 // @see Cipher
39 // @see BlockCipher
40 // @see EncryptedOutputStream
41 // @see EncryptedInputStream
42 // @see Rc4Cipher
43
44 public abstract class StreamCipher extends Cipher
45     {
46
47     /// Constructor.
48 public StreamCipher( int keySize )
49     {
50     super( keySize );
51     }
52
53     /// Encrypt a byte.
54 public abstract byte encrypt( byte clearText );
55
56     /// Decrypt a byte.
57 public abstract byte decrypt( byte cipherText );
58
59     /// Encrypt an array of bytes.
60 public void encrypt( byte[] clearText, byte[] cipherText )
61     {
62     encrypt( clearText, 0, cipherText, 0, clearText.length );
63     }
64
65     /// Decrypt an array of bytes.
66 public void decrypt( byte[] cipherText, byte[] clearText )
67     {
68     decrypt( cipherText, 0, clearText, 0, cipherText.length );
69     }
70
71     /// Encrypt some bytes.
72 // The default implementation just calls encrypt(byte) repeatedly.
73 // This can be overridden for speed.
74 public void encrypt( byte[] clearText, int clearOff, byte[] cipherText, int cipherOff, int len )
75     {
76     for ( int i = 0; i < len; ++i )
77         cipherText[cipherOff + i] = encrypt( clearText[clearOff + i] );
78     }
79
80     /// Decrypt some bytes.
81 // The default implementation just calls decrypt(byte) repeatedly.
82 // This can be overridden for speed.
83 public void decrypt( byte[] cipherText, int cipherOff, byte[] clearText, int clearOff, int len )
84     {
85     for ( int i = 0; i < len; ++i )
86         clearText[clearOff + i] = decrypt( cipherText[cipherOff + i] );
87     }
88
89     }
90
Popular Tags