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Java > Open Source Codes > Acme > Crypto > NullCipher


1 // NullCipher - the null encryption method
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 /// The null encryption method.
34 // <P>
35 // This is a block cipher that just copies input to output, unmodified.
36 // It's mostly for testing. However, using the null cipher in CBC mode,
37 // for example via EncryptedOutputStream and EncryptedInputStream, turns
38 // out to hash things up enough to protect against casual inspection.
39 // There may be applications where this is appropriate.
40 // <P>
41 // <A HREF="../../../resources/classes/Acme/Crypto/NullCipher.java">Fetch the software.</A><BR>
42 // <A HREF="../../../resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>
43 // <P>
44 // @see EncryptedOutputStream
45 // @see EncryptedInputStream
46
47 public class NullCipher extends BlockCipher
48     {
49
50     /// Constructor.
51 public NullCipher()
52     {
53     super( 0, 8 );
54     }
55
56
57     // Key routines.
58
59     /// Set the key. Null routine to avoid compilation error.
60 public void setKey( byte[] key )
61     {
62     throw new InternalError JavaDoc( "NullCipher does not need a key" );
63     }
64
65
66     // Block encryption routines.
67
68     /// "Encrypt" a block of eight bytes.
69 public void encrypt( byte[] clearText, int clearOff, byte[] cipherText, int cipherOff )
70     {
71     copyBlock( clearText, clearOff, cipherText, cipherOff, blockSize );
72     }
73
74     /// "Decrypt" a block of eight bytes.
75 public void decrypt( byte[] cipherText, int cipherOff, byte[] clearText, int clearOff )
76     {
77     copyBlock( cipherText, cipherOff, clearText, clearOff, blockSize );
78     }
79
80     }
81
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