/*
* Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Resin Open Source 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, or any warranty
* of NON-INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
*
* Free Software Foundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package com.caucho.server.distcache;
import com.caucho.util.HashKey;
import java.security.*;
/**
* Creates hashes for the identifiers.
*/
public class HashManager {
public static final int SIZE = 32;
public static final String HASH_ALGORITHM = "SHA-256";
public static final HashKey NULL = new HashKey(new byte[SIZE]);
private MessageDigest _digest;
/**
* Creates the manager
*/
public HashManager()
{
try {
_digest = MessageDigest.getInstance(HASH_ALGORITHM);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
/**
* Generates a hash from a string
*/
public HashKey generateHash(String key)
{
synchronized (_digest) {
_digest.reset();
int len = key.length();
for (int i = 0; i < len; i++) {
char ch = key.charAt(i);
_digest.update((byte) ch);
_digest.update((byte) (ch >> 8));
}
return new HashKey(_digest.digest());
}
}
/**
* Generates a hash from a prior hash and a string
*/
public HashKey generateHash(HashKey priorHash, String key)
{
synchronized (_digest) {
_digest.reset();
_digest.update(priorHash.getHash());
int len = key.length();
for (int i = 0; i < len; i++) {
char ch = key.charAt(i);
_digest.update((byte) ch);
_digest.update((byte) (ch >> 8));
}
return new HashKey(_digest.digest());
}
}
}