I have a WebSocket server written in javascript and send data to it from my CSharp application. Now how can I make sure that these are correct? I thought I could do something with hash values but I don't know how to do that. Does anyone have an idea or code example?
The first thing to understand is the types of WebSocket protocol/transports. WebSocket ws:// transport is basically unusable in terms of security as it uses HTTP. The wss:// protocol establishes a secure connection over TCP/HTTPS. The wss protocol, therefore, protects against man-in-the-middle attacks.
There is multiple methods to authenticate a user when setting up a WebSocket connection, and none are perfect. Since the standard WebSocket usage prevents additional headers from being set such as custom authentication headers, tried and true methods that would be used in a standard HTTPS request to verify the validity of a client can't be used.
The link here outlines some common methods to keep the client and server in sync while setting up a WebSocket connection, and still add some security so the server can keep track of what clients are opening WebSocket connections. There are a lot of workarounds listed for the server to safely receive sensitive, authentication data from the client.