01: // Cipher - an encryption template
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: /// An encryption template.
34: // <P>
35: // <A HREF="/resources/classes/Acme/Crypto/Cipher.java">Fetch the software.</A><BR>
36: // <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>
37: // <P>
38: // @see StreamCipher
39: // @see BlockCipher
40: // @see EncryptedOutputStream
41: // @see EncryptedInputStream
42:
43: public abstract class Cipher extends CryptoUtils {
44:
45: /// Constructor.
46: public Cipher(int keySize) {
47: this .keySize = keySize;
48: }
49:
50: /// How big a key is. Keyless ciphers use 0. Variable-length-key ciphers
51: // also use 0.
52: public int keySize;
53:
54: /// Return how big a key is.
55: public int keySize() {
56: return keySize;
57: }
58:
59: /// Set the key from a block of bytes.
60: public abstract void setKey(byte[] key);
61:
62: // Utility routines.
63:
64: /// Utility routine to set the key from a string.
65: public void setKey(String keyStr) {
66: setKey(makeKey(keyStr));
67: }
68:
69: /// Utility routine to turn a string into a key of the right length.
70: public byte[] makeKey(String keyStr) {
71: byte[] key;
72: if (keySize == 0)
73: key = new byte[keyStr.length()];
74: else
75: key = new byte[keySize];
76: int i, j;
77:
78: for (j = 0; j < key.length; ++j)
79: key[j] = 0;
80:
81: for (i = 0, j = 0; i < keyStr.length(); ++i, j = (j + 1)
82: % key.length)
83: key[j] ^= (byte) keyStr.charAt(i);
84:
85: return key;
86: }
87:
88: }
|