在很多項目中，為了安全安全考慮，需要對數據包進行加密處理，本文實例所述的即為C#加密代碼，在應用開發中有很大的實用價值。說起數據包加密，其實對C#編程者來說，應該是一個基礎的技巧，是進行C#程序設計人員必須要掌握的技能。
C#實現加密功能的核心代碼如下：
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 定義全局對象及變量 private IPEndPoint Server;//服務器端 private IPEndPoint Client;//客戶端 private Socket mySocket;//套接字 private EndPoint ClientIP;//IP地址 byte[] buffer, data;//接收緩存 bool blFlag = true;//標識是否第一次發送信息 bool ISPort = false;//判斷端口打開 int SendNum1, ReceiveNum1, DisNum1; //記錄窗體加載時的已發送/已接收/丟失的數據報 int SendNum2, ReceiveNum2, DisNum2; //記錄當前已發送/已接收/丟失的數據報 int SendNum3, ReceiveNum3, DisNum3; //緩存已發送/已接收/丟失的數據報 int port;//端口號 #endregion //異步接收信息 private void StartLister(IAsyncResult IAResult) { int Num = mySocket.EndReceiveFrom(IAResult, ref ClientIP); string strInfo = Encoding.Unicode.GetString(buffer, 0, Num); rtbContent.AppendText("用戶" + ClientIP.ToString()); rtbContent.AppendText("："); rtbContent.AppendText("/r/n"); rtbContent.AppendText(DecryptDES(strInfo, "mrsoftxk"));//對接收到的信息進行解密 rtbContent.AppendText("/r/n"); mySocket.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref ClientIP, new AsyncCallback(StartLister), null); } //初始化已發送、已接收和丟失的數據報 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()); } } //設置端口號 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;//打開指定端口號 } catch { } } //發送信息 private void button2_Click(object sender, EventArgs e) { if (ISPort == true)//判斷是否有打開的端口號 { IPGlobalProperties NetInfo = IPGlobalProperties.GetIPGlobalProperties(); UdpStatistics myUdpStat = null; myUdpStat = NetInfo.GetUdpIPv4Statistics(); try { if (blFlag == false)//非第一次發送 { 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; //記錄本次的發送數據報 ReceiveNum3 = ReceiveNum2;//記錄本次的接收數據報 DisNum3 = DisNum2; //記錄本次的丟失數據報 if (blFlag == true)//第一次發送 { 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");//加密要發送的信息 data = Encoding.Unicode.GetBytes(str); mySocket.SendTo(data, data.Length, SocketFlags.None, Client); rtbSend.Text = ""; } else { MessageBox.Show("請首先打開端口！", "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>組合鍵發送信息 private void rtbSend_KeyDown(object sender, KeyEventArgs e) { //當同時按下Ctrl和Enter時，發送消息 if (e.Control && e.KeyValue == 13) { e.Handled = true; button2_Click(this, null); } } //聊天記錄隨時滾動 private void rtbContent_TextChanged(object sender, EventArgs e) { rtbContent.ScrollToCaret(); } private static byte[] Keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };//密鑰 #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">加密密鑰,要求為8位</param> ///<returns>加密成功返回加密后的字符串，失敗返回源字符串</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">解密密鑰,要求為8位,和加密密鑰相同</param> ///<returns>解密成功返回解密后的字符串，失敗返源字符串</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 }} 本例備有詳細的注釋，對于開發者而言應該不難理解，讀者可以根據自身項目需要改進本例代碼以符合自身應用需求。
