Good day,

I am a self-taught developer aiming to expand my knowledge and improve my skills. Currently, I am working on establishing a secure WebSocket (WSS) connection in a C# console application using the WebSocketSharp library. Despite my efforts, I am encountering several issues and would appreciate some guidance.

Goal: Establish a secure WebSocket (WSS) connection between a server and a client using the WebSocketSharp library in a C# console application.

Current Status:

• WebSocket (ws) connection works over the internet using the domain name.
• WSS connection is problematic: The server starts without “HMAC is not supported” error, but the client immediately triggers ws.OnClose without ever triggering ws.OnOpen.

Problems:

1. In the Unity implementation, I encountered the “HMAC is not supported” error, which I tried to resolve using Bouncy Castle but without success.
2. In the Visual Studio C# console app, the WSS connection starts and immediately closes without establishing a successful connection.

Environment:

• C# Console App in Visual Studio 2022
• Unity Game Engine
• WebSocketSharp library: websocket-sharp-core(https://github.com/ImoutoChan/websocket-sharp-core)
• Windows OS
• Router port forwarding for server setup
• DuckDNS for domain name
• SSL certificate from Let’s Encrypt

Client Code:

using System;a
using WebSocketSharp;


namespace ClientLast
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                using (var ws = new WebSocket("ws://localhost:50001/Echo"))
                //using (var ws = new WebSocket("wss://abyza.duckdns.org:50001/Echo"))
                {
                    ws.OnMessage += (sender, e) =>
                        Console.WriteLine("Received from server: " + e.Data);

                    ws.OnOpen += (sender, e) =>
                        Console.WriteLine("Connection opened");

                    ws.OnClose += (sender, e) =>
                        Console.WriteLine("Connection closed: " + e.Reason);

                    ws.OnError += (sender, e) =>
                        Console.WriteLine("Error: " + e.Message);


                    ws.Connect();
                    ws.Send("Hello, World!");

                    Console.ReadKey(true);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error: {ex.Message}");
                Console.WriteLine($"Stack Trace: {ex.StackTrace}");
            }
        }
    }
}

Server Code:

using System;
using System.Security.Cryptography.X509Certificates;
using WebSocketSharp;
using WebSocketSharp.Server;


namespace serverLast
{


    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                var wssv = new WebSocketServer(System.Net.IPAddress.Any, 50001);
                //var wssv = new WebSocketServer(System.Net.IPAddress.Any, 50001,true);

                // Load the PFX certificate
                var cert = new X509Certificate2("D:\3_apps\5_vscode_projects\website server\sslcert - Copy//certificate.pfx", "pass");
                wssv.SslConfiguration.ServerCertificate = cert;

                wssv.AddWebSocketService<Echo>("/Echo");
                wssv.Start();

                Console.WriteLine("WebSocket server started on wss://localhost:443");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error starting server: {ex.Message}");
            }

            Console.ReadKey();
        }

        public class Echo : WebSocketBehavior
        {
            protected override void OnMessage(MessageEventArgs e)
            {
                Console.WriteLine($"Received message: {e.Data}");
                Send(e.Data);
            }
        }
    }


}

SSL Certificate:

• Obtained using DuckDNS and Let’s Encrypt’s Certbot
• Certificate files: cert.pem, chain.pem, fullchain.pem, privkey.pem
• Converted to .pfx using:

openssl pkcs12 -export -out certificate.pfx -in combined.pem

Other Condiderations:

• I used port forwarding on my home router to my laptop to serve the website, WebSocket, and SSL certificate server.
• I know the certificate works because I used the fullchain.pem and privkey.pem files in a Python file to run a simple website, which I could successfully open using HTTPS.
• To create the .pfx file, I first combined the fullchain.pem and privkey.pem into a single combined.pem file.

Questions:

1. What might be causing the immediate closure of the WSS connection in the C# console app?
2. How can I resolve the “HMAC is not supported” error in Unity for establishing a secure WebSocket connection?
3. Are there any additional configurations or steps I might have missed in setting up the WebSocketSharp library for secure connections?

Thank you for your assistance!