how can i encrypt my message when sending to the server? can some 1 add in the code for me, as i am unfamiliar with encryption?/ any help??

Question

i would like to encrypt my message when sending to the server from client, how can i do it?

Client

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.Net.Sockets;
using System.Threading;

namespace SocketClient
{

public partial class SocketClient : Form
{
    System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();
    NetworkStream serverStream = default(NetworkStream);
    string readData = null;


    public SocketClient()
    {
        InitializeComponent();
    }


    private void getMessage()
    {
        while (true)
        {
            serverStream = clientSocket.GetStream();
            int buffSize = 0;
            byte[] inStream = new byte[10025];
            buffSize = clientSocket.ReceiveBufferSize;
            serverStream.Read(inStream, 0, buffSize);
            string returndata = System.Text.Encoding.ASCII.GetString(inStream);
            readData = "" + returndata;
            msg();
        }
    }


    private void msg()
    {
        if (this.InvokeRequired)
            this.Invoke(new MethodInvoker(msg));
        else
            textDisplay.Text = textDisplay.Text + Environment.NewLine + " >> " + readData;
    }


    private void buttonConnect_Click(object sender, EventArgs e)
    {
        readData = "Conected to NYP Chat Server ...";
        msg();
        //clientSocket.Connect("127.0.0.1", 8888);
        clientSocket.Connect(textIP.Text, Convert.ToInt32(textPort.Text));
        serverStream = clientSocket.GetStream();

        byte[] outStream = System.Text.Encoding.ASCII.GetBytes(textName.Text + "$");
        serverStream.Write(outStream, 0, outStream.Length);
        serverStream.Flush();

        Thread ctThread = new Thread(getMessage);
        ctThread.Start();
    }

    private void buttonSend_Click(object sender, EventArgs e)
    {
        // Show msg box if no server is connected
        if (serverStream == null)
        {
            MessageBox.Show("Please connect to a server first!");
            return;
        }

        // Send text
        byte[] outStream = System.Text.Encoding.ASCII.GetBytes(textSend.Text + "$");
        serverStream.Write(outStream, 0, outStream.Length);
        serverStream.Flush();

        // Clear text
        textSend.Text = "";

    }

    private void textDisplay_TextChanged(object sender, EventArgs e)
    {
        textDisplay.SelectionStart = textDisplay.Text.Length;
        textDisplay.ScrollToCaret();
        textDisplay.Refresh();
    }

    private void textSend_TextChanged(object sender, EventArgs e)
    {
        buttonSend.Enabled = !string.IsNullOrEmpty(textSend.Text);
    }
}

}

server

using System;
using System.Threading;
using System.Net.Sockets;
using System.Text;
using System.Collections;

namespace ConsoleApplication1
{
class Program
{
    public static Hashtable clientsList = new Hashtable();

    static void Main(string[] args)
    {
        //TcpListener serverSocket = new TcpListener(portFromAppConfig);

        TcpListener serverSocket = new TcpListener(9999);
        TcpClient clientSocket = default(TcpClient);
        int counter = 0;

        serverSocket.Start();
        Console.WriteLine("Welcome to NYP Chat Server ");
        counter = 0;
        while ((true))
        {
            counter += 1;
            clientSocket = serverSocket.AcceptTcpClient();

            byte[] bytesFrom = new byte[10025];
            string dataFromClient = null;

            NetworkStream networkStream = clientSocket.GetStream();
            networkStream.Read(bytesFrom, 0, (int)clientSocket.ReceiveBufferSize);
            dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
            dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));

            clientsList.Add(dataFromClient, clientSocket);

            broadcast(dataFromClient + " Connected ", dataFromClient, false);

            Console.WriteLine(dataFromClient + " has join the chat room ");
            handleClinet client = new handleClinet();
            client.startClient(clientSocket, dataFromClient, clientsList);
        }

        clientSocket.Close();
        serverSocket.Stop();
        Console.WriteLine("exit");
        Console.ReadLine();
    }

    public static void broadcast(string msg, string uName, bool flag)
    {
        foreach (DictionaryEntry Item in clientsList)
        {
            TcpClient broadcastSocket;
            broadcastSocket = (TcpClient)Item.Value;
            NetworkStream broadcastStream = broadcastSocket.GetStream();
            Byte[] broadcastBytes = null;

            if (flag == true)
            {
                broadcastBytes = Encoding.ASCII.GetBytes(uName + " says : " + msg);
            }
            else
            {
                broadcastBytes = Encoding.ASCII.GetBytes(msg);
            }

            broadcastStream.Write(broadcastBytes, 0, broadcastBytes.Length);
            broadcastStream.Flush();
        }
    }  //end broadcast function
}//end Main class


public class handleClinet
{
    TcpClient clientSocket;
    string clNo;
    Hashtable clientsList;

    public void startClient(TcpClient inClientSocket, string clineNo, Hashtable cList)
    {
        this.clientSocket = inClientSocket;
        this.clNo = clineNo;
        this.clientsList = cList;
        Thread ctThread = new Thread(doChat);
        ctThread.Start();
    }

    private void doChat()
    {
        int requestCount = 0;
        byte[] bytesFrom = new byte[10025];
        string dataFromClient = null;
        Byte[] sendBytes = null;
        string serverResponse = null;
        string rCount = null;
        requestCount = 0;

        while ((true))
        {
            try
            {
                requestCount = requestCount + 1;
                NetworkStream networkStream = clientSocket.GetStream();
                networkStream.Read(bytesFrom, 0, (int)clientSocket.ReceiveBufferSize);
                dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
                dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));
                Console.WriteLine("From client - " + clNo + " : " + dataFromClient);
                rCount = Convert.ToString(requestCount);

                Program.broadcast(dataFromClient, clNo, true);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
        }//end while
    }//end doChat
} //end class handleClinet
}//end namespace

Answer 1

Take a look at this article. It shows symmetric encryption/decryption methods.

Answer 2

C# provides a namespace for cryptography System.Security.Cryptography... for start you could check that out... Or try to implement a cryptography algorithm like Vernamm which is the simplest and easiest to implement. Or if you want to be fully secured you should use both the System.Security.Cryptography namespace the System.Security.Cryptography.X509Certificates namespace.

Answer 3

Also, have a look here:

Aync Socket Server with Encryption and Compression on CodeProject.

Answer 4

Absolute simplest way is to rip all the code you wrote and just use WCF.

Next simplest way is to use a secure stream instead of the raw Network Stream, like SslStream or NegotiateStream. There a full blown sample at Secure Streams Sample that shows both the client and the server for NTLM/Kerberos and SChannel protocols (aka SSL/TLS).

One thing you should absolutely not do is write your own encryption. Encrypting messages is trivial and you'll find a myriad samples on the web. But creating a key exchange protocol so you actually have something to encrypt with is one of the hardest tasks in crypto. Use one of the industry acknowledged key exchange schemes like Kerberos or SSL/TLS, and these are already implemented in the two stream classes I linked.