DES加密、解密字符串算法

/*
* Created on Feb 27, 2012
*
* DesUtils.java
*
* Copyright (C) 2012 by Citicorp Software & Technology Services (Shanghai) Limited.
* All rights reserved. Citicorp Software & Technology Services (Shanghai) Limited
* claims copyright in this computer program as an unpublished work. Claim of copyright
* does not imply waiver of other rights.
*
* NOTICE OF PROPRIETARY RIGHTS
*
* This program is a confidential trade secret and the property of
* Citicorp Software & Technology Services (Shanghai) Limited. Use, examination,
* reproduction, disassembly, decompiling, transfer and/or disclosure to others of
* all or any part of this software program are strictly prohibited except by express
* written agreement with Citicorp Software & Technology Services (Shanghai) Limited.
*/
/*
* ---------------------------------------------------------------------------------
* Modification History
* Date               Author                     Version     Description
* Feb 27, 2012       gl65293                    1.0         New
* ---------------------------------------------------------------------------------
*/
/**
*
*/
package com.cemso.util;

/**
* @author gl65293
*
*/
import java.security.Key;
import java.security.Security;

import javax.crypto.Cipher;

/**
* DES加密和解密工具,可以对字符串进行加密和解密操作。
*
* @author cross
*         <p>
*         2012-2-27
*         </p>
*/
public class DesUtils {

    /** 字符串默认键值*/
    private static String strDefaultKey = "national";

    /** 加密工具*/
    private Cipher encryptCipher = null;

    /** 解密工具*/
    private Cipher decryptCipher = null;

    /**
     * 将byte数组转换为表示16进制值的字符串，如：byte[]{8,18}转换为：0813，和public static byte[]
     * hexStr2ByteArr(String strIn) 互为可逆的转换过程
     *
     * @param arrB
     *            需要转换的byte数组
     * @return 转换后的字符串
     * @throws Exception
     *             本方法不处理任何异常，所有异常全部抛出
     */
    public static String byteArr2HexStr(byte[] arrB) throws Exception {
        int iLen = arrB.length;
        // 每个byte用两个字符才能表示，所以字符串的长度是数组长度的两倍
        StringBuffer sb = new StringBuffer(iLen * 2);
        for (int i = 0; i < iLen; i++) {
            int intTmp = arrB[i];
            // 把负数转换为正数
            while (intTmp < 0) {
                intTmp = intTmp + 256;
            }
            // 小于0F的数需要在前面补0
            if (intTmp < 16) {
                sb.append("0");
            }
            sb.append(Integer.toString(intTmp, 16));
        }
        return sb.toString();
    }

    /**
     * 将表示16进制值的字符串转换为byte数组，和public static String byteArr2HexStr(byte[] arrB)
     * 互为可逆的转换过程
     *
     * @param strIn
     *           需要转换的字符串
     * @return 转换后的byte数组
     * @throws Exception
     *             本方法不处理任何异常，所有异常全部抛出
     * @author <a href="mailto:leo841001@163.com">LiGuoQing</a>
     */
    public static byte[] hexStr2ByteArr(String strIn) throws Exception {
        byte[] arrB = strIn.getBytes();
        int iLen = arrB.length;

        // 两个字符表示一个字节，所以字节数组长度是字符串长度除以2
        byte[] arrOut = new byte[iLen / 2];
        for (int i = 0; i < iLen; i = i + 2) {
            String strTmp = new String(arrB, i, 2);
            arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16);
        }
        return arrOut;
    }

    /**
     * 默认构造方法，使用默认密钥
     *
     * @throws Exception
     */
    public DesUtils() throws Exception {
        this(strDefaultKey);
    }

    /**
     * 指定密钥构造方法
     *
     * @param strKey
     *            指定的密钥
     * @throws Exception
     */

补充：综合编程 , 安全编程 ,