/*
* Copyright 2010 Srikanth Reddy Lingala  
* 
* Licensed under the Apache License, Version 2.0 (the "License"); 
* you may not use this file except in compliance with the License. 
* You may obtain a copy of the License at 
* 
* http://www.apache.org/licenses/LICENSE-2.0 
* 
* Unless required by applicable law or agreed to in writing, 
* software distributed under the License is distributed on an "AS IS" BASIS, 
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
* See the License for the specific language governing permissions and 
* limitations under the License. 
*/

package com.zip4j.crypto.PBKDF2;

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

/*
 * Source referred from Matthias Gartner's PKCS#5 implementation - 
 * see http://rtner.de/software/PBKDF2.html 
 */

public class MacBasedPRF implements PRF
{
    protected Mac mac;

    protected int hLen;

    protected String macAlgorithm;

    public MacBasedPRF(String macAlgorithm)
    {
        this.macAlgorithm = macAlgorithm;
        try
        {
            mac = Mac.getInstance(macAlgorithm);
            hLen = mac.getMacLength();
        }
        catch (NoSuchAlgorithmException e)
        {
            throw new RuntimeException(e);
        }
    }

    public MacBasedPRF(String macAlgorithm, String provider)
    {
        this.macAlgorithm = macAlgorithm;
        try
        {
            mac = Mac.getInstance(macAlgorithm, provider);
            hLen = mac.getMacLength();
        }
        catch (NoSuchAlgorithmException e)
        {
            throw new RuntimeException(e);
        }
        catch (NoSuchProviderException e)
        {
            throw new RuntimeException(e);
        }
    }

    public byte[] doFinal(byte[] M)
    {
        byte[] r = mac.doFinal(M);
        return r;
    }
    
    public byte[] doFinal() {
    	byte[] r = mac.doFinal();
        return r;
    }

    public int getHLen()
    {
        return hLen;
    }

    public void init(byte[] P)
    {
        try
        {
            mac.init(new SecretKeySpec(P, macAlgorithm));
        }
        catch (InvalidKeyException e)
        {
            throw new RuntimeException(e);
        }
    }
    
    public void update(byte[] U) {
    	
    	try {
			mac.update(U);
		} catch (IllegalStateException e) {
			throw new RuntimeException(e);
		}
    
    }
    
    public void update (byte[] U, int start, int len) {
    	try {
			mac.update(U, start, len);
		} catch (IllegalStateException e) {
			throw new RuntimeException(e);
		}
    }
}
