01: // NullCipher - the null encryption method
02: //
03: // Copyright (C) 1996 by Jef Poskanzer <jef@acme.com>. All rights reserved.
04: //
05: // Redistribution and use in source and binary forms, with or without
06: // modification, are permitted provided that the following conditions
07: // are met:
08: // 1. Redistributions of source code must retain the above copyright
09: // 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: /// Constructor.
50: public NullCipher() {
51: super (0, 8);
52: }
53:
54: // Key routines.
55:
56: /// Set the key. Null routine to avoid compilation error.
57: public void setKey(byte[] key) {
58: throw new InternalError("NullCipher does not need a key");
59: }
60:
61: // Block encryption routines.
62:
63: /// "Encrypt" a block of eight bytes.
64: public void encrypt(byte[] clearText, int clearOff,
65: byte[] cipherText, int cipherOff) {
66: copyBlock(clearText, clearOff, cipherText, cipherOff, blockSize);
67: }
68:
69: /// "Decrypt" a block of eight bytes.
70: public void decrypt(byte[] cipherText, int cipherOff,
71: byte[] clearText, int clearOff) {
72: copyBlock(cipherText, cipherOff, clearText, clearOff, blockSize);
73: }
74:
75: }
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