C#与Java同步加密解密DES算法

在实际项目中，往往前端和后端使用不同的语言。比如使用C#开发客户端，使用Java开发服务器端。有时出于安全性考虑需要将字符加密传输后，由服务器解密获取。本文介绍一种采用DES算法的C#与Java同步加密解密的代码。

C#端代码：（注意：DES的秘钥采用8位字符）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Globalization;
using System.Threading.Tasks;
using System.Security.Cryptography;
using System.IO;

namespace ChatDemo.util
{
    public static class PasswordHelper
    {
        ///<summary><![CDATA[字符串DES加密函数]]></summary>
        ///<param name="str"><![CDATA[被加密字符串 ]]></param>
        ///<param name="key"><![CDATA[密钥 ]]></param>
        ///<returns><![CDATA[加密后字符串]]></returns>
        public static string EncodeDES(string str, string key)
        {
            try
            {
                DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
                provider.Key = Encoding.ASCII.GetBytes(key.Substring(0, 8));
                provider.IV = Encoding.ASCII.GetBytes(key.Substring(0, 8));
                byte[] bytes = Encoding.GetEncoding("UTF-8").GetBytes(str);
                MemoryStream stream = new MemoryStream();
                CryptoStream stream2 = new CryptoStream(stream, provider.CreateEncryptor(), CryptoStreamMode.Write);
                stream2.Write(bytes, 0, bytes.Length);
                stream2.FlushFinalBlock();
                StringBuilder builder = new StringBuilder();
                foreach (byte num in stream.ToArray())
                {
                    builder.AppendFormat("{0:X2}", num);
                }
                stream.Close();
                return builder.ToString();
            }
            catch (Exception) { return "xxxx"; }
        }
        ///<summary><![CDATA[字符串DES解密函数]]></summary>
        ///<param name="str"><![CDATA[被解密字符串 ]]></param>
        ///<param name="key"><![CDATA[密钥 ]]></param>
        ///<returns><![CDATA[解密后字符串]]></returns>
        public static string DecodeDES(string str, string key)
        {
            try
            {
                DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
                provider.Key = Encoding.ASCII.GetBytes(key.Substring(0, 8));
                provider.IV = Encoding.ASCII.GetBytes(key.Substring(0, 8));
                byte[] buffer = new byte[str.Length / 2];
                for (int i = 0; i < (str.Length / 2); i++)
                {
                    int num2 = Convert.ToInt32(str.Substring(i * 2, 2), 0x10);
                    buffer[i] = (byte)num2;
                }
                MemoryStream stream = new MemoryStream();
                CryptoStream stream2 = new CryptoStream(stream, provider.CreateDecryptor(), CryptoStreamMode.Write);
                stream2.Write(buffer, 0, buffer.Length);
                stream2.FlushFinalBlock();
                stream.Close();
                return Encoding.GetEncoding("UTF-8").GetString(stream.ToArray());
            }
            catch (Exception) { return ""; }
        }
    }
}

Java端代码：

package com.hbcloudwide.didaoa.chatserver.util;


import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

import org.apache.commons.codec.digest.DigestUtils;

/**
 * 密码加密解密处理工具类
 *
 * @author lee
 *
 */
public class PasswordUtil {

    // 解密数据
    /**
     * DES解密
     * @param message
     * @param key
     * @return
     * @throws Exception
     *
     * lee on 2016-12-26 00:28:18
     */
    public static String DecodeDES(String message, String key) throws Exception {

        byte[] bytesrc = convertHexString(message);
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF-8"));
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        SecretKey secretKey = keyFactory.generateSecret(desKeySpec);
        IvParameterSpec iv = new IvParameterSpec(key.getBytes("UTF-8"));
        cipher.init(Cipher.DECRYPT_MODE, secretKey, iv);
        byte[] retByte = cipher.doFinal(bytesrc);
        return new String(retByte);
    }

    /**
     * DES加密
     * @param message
     * @param key
     * @return
     * @throws Exception
     *
     * lee on 2016-12-26 00:28:28
     */
    public static byte[] EncodeDES(String message, String key) throws Exception {
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF-8"));
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        SecretKey secretKey = keyFactory.generateSecret(desKeySpec);
        IvParameterSpec iv = new IvParameterSpec(key.getBytes("UTF-8"));
        cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);
        return cipher.doFinal(message.getBytes("UTF-8"));
    }

    /**
     * MD5加密
     * 使用org.apache.commons.codec.digest.DigestUtils加密
     * http://commons.apache.org/proper/commons-codec/download_codec.cgi
     * @param message
     * @return
     *
     * lee on 2016-12-26 00:28:28
         */
    public static String EncodeMD5(String message) {
        return DigestUtils.md5Hex(message);
    }


    public static byte[] convertHexString(String ss) {
        byte digest[] = new byte[ss.length() / 2];
        for (int i = 0; i < digest.length; i++) {
            String byteString = ss.substring(2 * i, 2 * i + 2);
            int byteValue = Integer.parseInt(byteString, 16);
            digest[i] = (byte) byteValue;
        }
        return digest;
    }

    public static String toHexString(byte b[]) {
        StringBuffer hexString = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            String plainText = Integer.toHexString(0xff & b[i]);
            if (plainText.length() < 2)
                plainText = "0" + plainText;
            hexString.append(plainText);
        }
        return hexString.toString();
    }


}

C# DES加密后的字符传递到Java端获取后，可以正确进行解密。反之亦然。
BTW：Java代码中有一个方法用来进行MD5加密，采用org.apache.commons.codec.digest.DigestUtils进行加密。