C#实现数据包加密与解密实例详解

在很多项目中，为了安全安全考虑，需要对数据包进行加密处理，本文实例所述的即为c#加密代码，在应用开发中有很大的实用价值。说起数据包加密，其实对c#编程者来说，应该是一个基础的技巧，是进行c#程序设计人员必须要掌握的技能。

c#实现加密功能的核心代码如下：

using system;
using system.collections.generic;
using system.componentmodel;
using system.data;
using system.drawing;
using system.linq;
using system.text;
using system.windows.forms;
using system.threading;
using system.net;
using system.net.sockets;
using system.net.networkinformation;
using system.security.cryptography;
using system.io;
namespace encryptdatareport
{
  public partial class form1 : form
  {
    public form1()
    {
      initializecomponent();
    }
    #region 定义全局对象及变量
    private ipendpoint server;//服务器端
    private ipendpoint client;//客户端
    private socket mysocket;//套接字
    private endpoint clientip;//ip地址
    byte[] buffer, data;//接收缓存
    bool blflag = true;//标识是否第一次发送信息
    bool isport = false;//判断端口打开
    int sendnum1, receivenum1, disnum1; //记录窗体加载时的已发送\已接收\丢失的数据报
    int sendnum2, receivenum2, disnum2; //记录当前已发送\已接收\丢失的数据报
    int sendnum3, receivenum3, disnum3; //缓存已发送\已接收\丢失的数据报
    int port;//端口号
    #endregion
    //异步接收信息
    private void startlister(iasyncresult iaresult)
    {
      int num = mysocket.endreceivefrom(iaresult, ref clientip);
      string strinfo = encoding.unicode.getstring(buffer, 0, num);
      rtbcontent.appendtext("用户" + clientip.tostring());
      rtbcontent.appendtext("：");
      rtbcontent.appendtext("\r\n");
      rtbcontent.appendtext(decryptdes(strinfo, "mrsoftxk"));//对接收到的信息进行解密
      rtbcontent.appendtext("\r\n");
      mysocket.beginreceivefrom(buffer, 0, buffer.length, socketflags.none, ref clientip, new asynccallback(startlister), null);
    }
    //初始化已发送、已接收和丢失的数据报
    private void form1_load(object sender, eventargs e)
    {
      if (blflag == true)
      {
        ipglobalproperties netinfo = ipglobalproperties.getipglobalproperties();
        udpstatistics myudpstat = null;
        myudpstat = netinfo.getudpipv4statistics();
        sendnum1 = int32.parse(myudpstat.datagramssent.tostring());
        receivenum1 = int32.parse(myudpstat.datagramsreceived.tostring());
        disnum1 = int32.parse(myudpstat.incomingdatagramsdiscarded.tostring());
      }
    }
    //设置端口号
    private void button4_click(object sender, eventargs e)
    {
      try
      {
        port = convert.toint32(textbox4.text);
        checkforillegalcrossthreadcalls = false;
        buffer = new byte[1024];
        data = new byte[1024];
        server = new ipendpoint(ipaddress.any, port);
        client = new ipendpoint(ipaddress.broadcast, port);
        clientip = (endpoint)server;
        mysocket = new socket(addressfamily.internetwork, sockettype.dgram, protocoltype.udp);
        mysocket.setsocketoption(socketoptionlevel.socket, socketoptionname.broadcast, 1);
        mysocket.bind(server);
        mysocket.beginreceivefrom(buffer, 0, buffer.length, socketflags.none, ref clientip, new asynccallback(startlister), null);
        isport = true;//打开指定端口号
      }
      catch { }
    }
    //发送信息
    private void button2_click(object sender, eventargs e)
    {
      if (isport == true)//判断是否有打开的端口号
      {
        ipglobalproperties netinfo = ipglobalproperties.getipglobalproperties();
        udpstatistics myudpstat = null;
        myudpstat = netinfo.getudpipv4statistics();
        try
        {
          if (blflag == false)//非第一次发送
          {
            sendnum2 = int32.parse(myudpstat.datagramssent.tostring());
            receivenum2 = int32.parse(myudpstat.datagramsreceived.tostring());
            disnum2 = int32.parse(myudpstat.incomingdatagramsdiscarded.tostring());
            textbox1.text = convert.tostring(sendnum2 - sendnum3);
            textbox2.text = convert.tostring(receivenum2 - receivenum3);
            textbox3.text = convert.tostring(disnum2 - disnum3);
          }
          sendnum2 = int32.parse(myudpstat.datagramssent.tostring());
          receivenum2 = int32.parse(myudpstat.datagramsreceived.tostring());
          disnum2 = int32.parse(myudpstat.incomingdatagramsdiscarded.tostring());
          sendnum3 = sendnum2; //记录本次的发送数据报
          receivenum3 = receivenum2;//记录本次的接收数据报
          disnum3 = disnum2; //记录本次的丢失数据报
          if (blflag == true)//第一次发送
          {
            textbox1.text = convert.tostring(sendnum2 - sendnum1);
            textbox2.text = convert.tostring(receivenum2 - receivenum1);
            textbox3.text = convert.tostring(disnum2 - disnum1);
            blflag = false;
          }
        }
        catch (exception ex)
        {
          messagebox.show(ex.message, "提示信息", messageboxbuttons.ok, messageboxicon.information);
        }
        string str = encryptdes(rtbsend.text, "mrsoftxk");//加密要发送的信息
        data = encoding.unicode.getbytes(str);
        mysocket.sendto(data, data.length, socketflags.none, client);
        rtbsend.text = "";
      }
      else
      {
        messagebox.show("请首先打开端口！", "提示", messageboxbuttons.ok, messageboxicon.information);
        button4.focus();
      }
    }
    //清屏
    private void button1_click(object sender, eventargs e)
    {
      rtbcontent.clear();
    }
    //退出
    private void button3_click(object sender, eventargs e)
    {
      application.exit();
    }
    //按<ctrl+enter>组合键发送信息
    private void rtbsend_keydown(object sender, keyeventargs e)
    {
      //当同时按下ctrl和enter时，发送消息
      if (e.control && e.keyvalue == 13)
      {
        e.handled = true;
        button2_click(this, null);
      }
    }
    //聊天记录随时滚动
    private void rtbcontent_textchanged(object sender, eventargs e)
    {
      rtbcontent.scrolltocaret();
    }
    private static byte[] keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xab, 0xcd, 0xef };//密钥
    #region des加密字符串
    ///<summary>  
    ///des加密字符串  
    ///</summary>  
    ///<param name="str">待加密的字符串</param>  
    ///<param name="key">加密密钥,要求为8位</param>  
    ///<returns>加密成功返回加密后的字符串，失败返回源字符串</returns>  
    public string encryptdes(string str, string key)
    {
      try
      {
        byte[] rgbkey = encoding.utf8.getbytes(key.substring(0, 8));
        byte[] rgbiv = keys;
        byte[] inputbytearray = encoding.utf8.getbytes(str);
        descryptoserviceprovider mydes = new descryptoserviceprovider();
        memorystream mstream = new memorystream();
        cryptostream cstream = new cryptostream(mstream, mydes.createencryptor(rgbkey, rgbiv), cryptostreammode.write);
        cstream.write(inputbytearray, 0, inputbytearray.length);
        cstream.flushfinalblock();
        return convert.tobase64string(mstream.toarray());
      }
      catch
      {
        return str;
      }
    }
    #endregion
    #region des解密字符串
    ///<summary>  
    ///des解密字符串  
    ///</summary>  
    ///<param name="str">待解密的字符串</param>  
    ///<param name="key">解密密钥,要求为8位,和加密密钥相同</param>  
    ///<returns>解密成功返回解密后的字符串，失败返源字符串</returns>  
    public string decryptdes(string str, string key)
    {
      try
      {
        byte[] rgbkey = encoding.utf8.getbytes(key);
        byte[] rgbiv = keys;
        byte[] inputbytearray = convert.frombase64string(str);
        descryptoserviceprovider mydes = new descryptoserviceprovider();
        memorystream mstream = new memorystream();
        cryptostream cstream = new cryptostream(mstream, mydes.createdecryptor(rgbkey, rgbiv), cryptostreammode.write);
        cstream.write(inputbytearray, 0, inputbytearray.length);
        cstream.flushfinalblock();
        return encoding.utf8.getstring(mstream.toarray());
      }
      catch
      {
        return str;
      }
    }
    #endregion
  }
}

本例备有详细的注释，对于开发者而言应该不难理解，读者可以根据自身项目需要改进本例代码以符合自身应用需求。