试问用DES加密解密是否安全

   数据加密现在有很多方式，现在在思考系统中是采用不可逆加密还是采用可逆加密？是采用MD5加密还是采用DES加密？

下面给出一个例子：采用md5加密：

加密字符串是：admin

密文是：21232F297A57A5A743894A0E4A801FC3

但是复制密文在百度中随便搜索MD5解密，然后输入进行就显示解密后内容为：admin

采用DES加密：

因为DES解密是可以根据传入的Key值，然后产生一个密文

比如参考代码：

/**
* DescKey.java
* 版权所有(C) 2012
* 创建:cuiran 2012-05-21 10:32:16
*/
package com.wpn.web.util;

import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

/**
* DES 加密
* @author cuiran
* @version TODO
*/
public class DescKey {

    Key key;

    public DescKey(String str) {
        setKey(str);// 生成密匙
    }

    public DescKey() {
        setKey("bjwpn");
    }

    /**
     * 根据参数生成KEY
     */
    public void setKey(String strKey) {
        try {
            KeyGenerator _generator = KeyGenerator.getInstance("DES");
            _generator.init(new SecureRandom(strKey.getBytes()));
            this.key = _generator.generateKey();
            _generator = null;
        } catch (Exception e) {
            throw new RuntimeException(
                    "Error initializing SqlMap class. Cause: " + e);
        }
    }

    /**
     * 加密String明文输入,String密文输出
     */
    public String getEncString(String strMing) {
        byte[] byteMi = null;
        byte[] byteMing = null;
        String strMi = "";
        BASE64Encoder base64en = new BASE64Encoder();
        try {
            byteMing = strMing.getBytes("UTF8");
            byteMi = this.getEncCode(byteMing);
            strMi = base64en.encode(byteMi);
        } catch (Exception e) {
            throw new RuntimeException(
                    "Error initializing SqlMap class. Cause: " + e);
        } finally {
            base64en = null;
            byteMing = null;
            byteMi = null;
        }
        return strMi;
    }

    /**
     * www.zzzyk.com 解密以String密文输入,String明文输出
     *
     * @param strMi
     * @return
     */
    public String   getDesString(String strMi) {
        BASE64Decoder base64De = new BASE64Decoder();
        byte[] byteMing = null;
        byte[] byteMi = null;
        String strMing = "";
        try {
            byteMi = base64De.decodeBuffer(strMi);
            byteMing = this.getDesCode(byteMi);
            strMing = new String(byteMing, "UTF8");
        } catch (Exception e) {
            throw new RuntimeException(
                    "Error initializing SqlMap class. Cause: " + e);
        } finally {
            base64De = null;
            byteMing = null;
            byteMi = null;
        }
        return strMing;
    }

    /**
     * 加密以byte[]明文输入,byte[]密文输出
     *
     * @param byteS
     * @return
     */
    private byte[] getEncCode(byte[] byteS) {
        byte[] byteFina = null;
        Cipher cipher;
        try {
            cipher = Cipher.getInstance("DES");
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byteFina = cipher.doFinal(byteS);
        } catch (Exception e) {
            throw new RuntimeException(
                    "Error initializing SqlMap class. Cause: " + e

补充：综合编程 , 安全编程 ,