Mega Code Archive
AtkinsonHash utility class implements the hash algorithm used by HyperCards ask password command
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/*
* Copyright © 2009-2011 Rebecca G. Bettencourt / Kreative Software
* <p>
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* <a href="http://www.mozilla.org/MPL/">http://www.mozilla.org/MPL/</a>
* <p>
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
* License for the specific language governing rights and limitations
* under the License.
* <p>
* Alternatively, the contents of this file may be used under the terms
* of the GNU Lesser General Public License (the "LGPL License"), in which
* case the provisions of LGPL License are applicable instead of those
* above. If you wish to allow use of your version of this file only
* under the terms of the LGPL License and not to allow others to use
* your version of this file under the MPL, indicate your decision by
* deleting the provisions above and replace them with the notice and
* other provisions required by the LGPL License. If you do not delete
* the provisions above, a recipient may use your version of this file
* under either the MPL or the LGPL License.
* @since OpenXION 0.9
* @author Rebecca G. Bettencourt, Kreative Software
*/
//package com.kreative.openxion.util;
import java.io.UnsupportedEncodingException;
/**
* The AtkinsonHash utility class implements the hash algorithm used by
* HyperCard's ask password command.
*
* @since OpenXION 0.9
* @author Rebecca G. Bettencourt, Kreative Software
*/
public class AtkinsonHash {
private AtkinsonHash() {
}
public static int hash(String password) {
try {
return hash(password.toLowerCase().getBytes("MACROMAN"));
} catch (UnsupportedEncodingException uee) {
return hash(password.toLowerCase().getBytes());
}
}
/* From: Anthony DeRobertis <derobert@erols.com> */
/* Date: 22-May-2001 11:08:56 GMT */
/* HyperCard's password hashing is essentially as follows: */
public static int hash(byte[] data) {
if (data == null || data.length == 0)
return 0x42696C6C;
else {
int hash = 0;
/*
* Seed the Toolbox PRNG with chartonum(char 1 of password) + the
* length of password
*/
int seed = (data[0] & 0xFF) + data.length;
/* Loop through all the BITS of password */
for (byte b : data) {
for (int m = 0x80; m != 0; m >>>= 1) {
/* Call Random() */
long newSeed = (seed & 0xFFFFFFFFL) * 0x41A7L;
while (newSeed >= 0x80000000L) {
newSeed = (newSeed & 0x7FFFFFFFL) + (newSeed >>> 31L);
}
seed = (newSeed == 0x7FFFFFFFL) ? 0 : (int) newSeed;
/* If the bit is set, add in the _new_ random seed */
if ((b & m) != 0)
hash += seed;
}
}
/* Return accumulator */
return hash;
}
}
/* [ A little reverse engineering can go a long way ;-) ] */
}
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