/* HMACT64 keyed hashing algorithm
* Copyright (C) 2003 "Eric Glass"
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
import java.security.MessageDigest;
/**
* This is an implementation of the HMACT64 keyed hashing algorithm.
* HMACT64 is defined by Luke Leighton as a modified HMAC-MD5 (RFC 2104)
* in which the key is truncated at 64 bytes (rather than being hashed
* via MD5).
*/
public class HMACT64 extends MessageDigest implements Cloneable {
private static final int BLOCK_LENGTH = 64;
private static final byte IPAD = (byte) 0x36;
private static final byte OPAD = (byte) 0x5c;
private MessageDigest md5;
private byte[] ipad = new byte[BLOCK_LENGTH];
private byte[] opad = new byte[BLOCK_LENGTH];
/**
* Creates an HMACT64 instance which uses the given secret key material.
*
* @param key The key material to use in hashing.
*/
public HMACT64(byte[] key) {
super("HMACT64");
int length = Math.min(key.length, BLOCK_LENGTH);
for (int i = 0; i < length; i++) {
ipad[i] = (byte) (key[i] ^ IPAD);
opad[i] = (byte) (key[i] ^ OPAD);
}
for (int i = length; i < BLOCK_LENGTH; i++) {
ipad[i] = IPAD;
opad[i] = OPAD;
}
try {
md5 = MessageDigest.getInstance("MD5");
} catch (Exception ex) {
throw new IllegalStateException(ex.getMessage());
}
engineReset();
}
private HMACT64(HMACT64 hmac) throws CloneNotSupportedException {
super("HMACT64");
this.ipad = hmac.ipad;
this.opad = hmac.opad;
this.md5 = (MessageDigest) hmac.md5.clone();
}
public Object clone() {
try {
return new HMACT64(this);
} catch (CloneNotSupportedException ex) {
throw new IllegalStateException(ex.getMessage());
}
}
protected byte[] engineDigest() {
byte[] digest = md5.digest();
md5.update(opad);
return md5.digest(digest);
}
protected int engineDigest(byte[] buf, int offset, int len) {
byte[] digest = md5.digest();
md5.update(opad);
md5.update(digest);
try {
return md5.digest(buf, offset, len);
} catch (Exception ex) {
throw new IllegalStateException();
}
}
protected int engineGetDigestLength() {
return md5.getDigestLength();
}
protected void engineReset() {
md5.reset();
md5.update(ipad);
}
protected void engineUpdate(byte b) {
md5.update(b);
}
protected void engineUpdate(byte[] input, int offset, int len) {
md5.update(input, offset, len);
}
}