pbewithmd5anddes.java

面向应用的智能安全代理平台和工具包是一个综合网络应用的安全共性需求而设计和实现的一个通用性的网络信息安全应用支撑平台

package au.net.aba.crypto.provider;

/*
 * $Id: PBEWithMD5AndDES.java,v 1.3 1999/01/22 06:00:47 leachbj Exp $
 * $Author: leachbj $
 *
 * Copyright (C) 1996-1998 Australian Business Access Pty Ltd.
 * All rights reserved.
 * 
 * Use, modification, copying and distribution of this software is subject the
 * terms and conditions of the ABA Public Licence. See the file
 * "PUBLIC_LICENCE" for additional information.
 *
 * If you have not received a copy of the Public Licence, you must destroy all
 * copies of this file immediately. 
 *
 * $Source: /aba/CVSROOT/jdk1.1/src/au.net.aba/crypto/provider/PBEWithMD5AndDES.java,v $
 * $Revision: 1.3 $
 * $Date: 1999/01/22 06:00:47 $
 * $State: Exp $
 */

import java.security.*;

import java.security.*;
import java.security.spec.*;

import javax.crypto.*;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

/**
 * This Cipher implements password based encryption (PBE) as specified
 * in PKCS#5.  This Cipher uses MD5 to convert the password into a
 * DES Key and an initialisation vector.  DES is then used in
 * CBC mode (with PKCS#5 padding) to encrypt or decrypt the data.
 */
public class PBEWithMD5AndDES extends PBE
{
	public final static String ident = "$Id: PBEWithMD5AndDES.java,v 1.3 1999/01/22 06:00:47 leachbj Exp $";

	public PBEWithMD5AndDES()
	{
		super("DES/CBC/PKCS5Padding");
	}
	/**
	 * Initialises the cipher for encrypt or decryption using the
	 * provided algorithm parameters.
	 *
	 * @param opmode Encrypt/Decrypt
	 * @param salt The salt to add to the password
	 * @param iteration The iteration count for key generation
	 * @param password The actual password to use in the key generation
	 */
	protected void initCipher(
		int opmode,
		byte[] salt,
		int iteration,
		char[] password)
	{
		// Convert password into bytes
		byte[] bytes = new byte[password.length];
		for (int i = 0; i < password.length; i++)
		{
			bytes[i] = (byte)password[i];
		}

		try
		{
			MessageDigest digest =
				MessageDigest.getInstance("MD5", "ABA");
			for (int i = 0; i < iteration; i++)
			{
				digest.update(bytes, 0, bytes.length);
				digest.update(salt, 0, salt.length);
			}
			byte[] digestBytes = digest.digest();

			DESKeySpec keySpec = new DESKeySpec(digestBytes);
			SecretKeyFactory skf =
				SecretKeyFactory.getInstance("DES");
			SecretKey secKey = skf.generateSecret(keySpec);

			IvParameterSpec pSpec = new IvParameterSpec(digestBytes,
				digestBytes.length - 8, 8);

			/*
			 * initalise cipher with out new key and an
			 * initialisation vector of the last 8 bytes
			 * of the digest
			 */
			cipher.init(opmode, secKey, pSpec);
		}
		catch(Exception e)
		{
			throw new ExceptionInInitializerError(e);
		}
	}
}