AJAX在C#中處理WebSocket消息加密與解密

在C#中，處理WebSocket消息的加密和解密通常涉及到使用SSL/TLS來保護數據傳輸的安全。這里是一個簡單的示例，展示了如何在C#中使用WebSocket和SSL/TLS來發送和接收加密消息。

首先，你需要安裝System.Net.WebSockets和System.Security.Cryptography.X509Certificates命名空間。

using System;
using System.Net.WebSockets;
using System.Security.Cryptography.X509Certificates;
using System.Threading;
using System.Threading.Tasks;

接下來，創建一個WebSocket服務器，使用SSL/TLS來保護連接。

class WebSocketServer
{
    private readonly Uri _uri;
    private readonly X509Certificate2 _certificate;

    public WebSocketServer(Uri uri, string certificatePath, string certificatePassword)
    {
        _uri = uri;
        _certificate = new X509Certificate2(certificatePath, certificatePassword);
    }

    public async Task StartAsync()
    {
        using (var listener = new HttpListener())
        {
            listener.Prefixes.Add(_uri.ToString());
            listener.Start();

            while (true)
            {
                var context = await listener.GetContextAsync();
                if (context.Request.IsWebSocketRequest)
                {
                    ProcessWebSocketRequest(context);
                }
            }
        }
    }

    private async void ProcessWebSocketRequest(HttpListenerContext context)
    {
        var webSocketContext = await context.AcceptWebSocketAsync(subProtocol: null, keepAliveInterval: TimeSpan.FromSeconds(30), receiveBufferSize: 1024, _certificate);
        var webSocket = webSocketContext.WebSocket;

        var buffer = new byte[1024];
        var result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);

        while (!result.CloseStatus.HasValue)
        {
            // Process received message
            var message = Encoding.UTF8.GetString(buffer, 0, result.Count);
            Console.WriteLine($"Received message: {message}");

            // Send response
            var response = Encoding.UTF8.GetBytes("Hello from the server!");
            await webSocket.SendAsync(new ArraySegment<byte>(response), WebSocketMessageType.Text, true, CancellationToken.None);

            result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
        }

        await webSocket.CloseAsync(result.CloseStatus.Value, result.CloseStatusDescription, CancellationToken.None);
    }
}

現在，你可以創建一個WebSocket客戶端，用于連接到服務器并發送和接收加密消息。

class WebSocketClient
{
    private readonly Uri _uri;

    public WebSocketClient(Uri uri)
    {
        _uri = uri;
    }

    public async Task ConnectAsync()
    {
        using (var client = new ClientWebSocket())
        {
            client.Options.RemoteCertificateValidationCallback = (sender, certificate, chain, sslPolicyErrors) => true; // Accept any certificate for demonstration purposes
            await client.ConnectAsync(_uri, CancellationToken.None);

            // Send message
            var message = Encoding.UTF8.GetBytes("Hello from the client!");
            await client.SendAsync(new ArraySegment<byte>(message), WebSocketMessageType.Text, true, CancellationToken.None);

            // Receive response
            var buffer = new byte[1024];
            var result = await client.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
            var response = Encoding.UTF8.GetString(buffer, 0, result.Count);
            Console.WriteLine($"Received response: {response}");

            await client.CloseAsync(WebSocketCloseStatus.NormalClosure, "Bye", CancellationToken.None);
        }
    }
}

最后，你可以在主程序中啟動WebSocket服務器和客戶端，以測試加密和解密的功能。

static async Task Main(string[] args)
{
    var serverUri = new Uri("wss://localhost:8080/");
    var server = new WebSocketServer(serverUri, "path/to/your/certificate.pfx", "your_certificate_password");
    var client = new WebSocketClient(serverUri);

    Task.Run(() => server.StartAsync());
    await Task.Delay(1000); // Give the server some time to start
    await client.ConnectAsync();
}

請注意，這個示例僅用于演示目的，實際應用中你需要根據自己的需求進行調整。同時，確保使用正確的證書文件路徑和密碼。