Setting up secure web sockets (wss) service for my https web app

Question

I have this web app that is served via https, and now it needs to use a websocket service that is served from another server. Chrome, Firefox and Internet Explorer complain right away that if the application is secure (https), then it is not allowed to connect to an insecure websocket service (ws:// URI). Strangely, Apple Safari doesn't complain so.

Well, fair enough, I assumed any globally trusted certificate would be fine to be installed at the websocket server side, to enable secure service (wss:// URI). However the company that maintains the socket server claims that they have to install there the very same certificate that secures my web application. I read in webs that the wss will not run with self-signed certificate, but nowhere that it must be the same certificate that the calling web site runs on.

Since we are talking sharing a certificate key file with 3rd party, I wanted to double check this. If my secure site runs at domain first.com, and the websocket server at IP address a.b.c.d, what kind of certificate should be installed on the websocket server to enable the communication? On one hand, that would be a kind of cross-site scripting, but perhaps the browser security model allows it, assuming the user knows what they want?

Answer 1

Since we are talking sharing a certificate key file with 3rd party, I wanted to double check this. If my secure site runs at domain first.com, and the websocket server at IP address a.b.c.d, what kind of certificate should be installed on the websocket server to enable the communication? On one hand, that would be a kind of cross-site scripting, but perhaps the browser security model allows it, assuming the user knows what they want?

You cannot provide a certificate for an IP address. In order to use WSS:// you need to connect to a domain name, and have a valid certificate for that domain name. So you need a SSL certificate for the domain name of your WebSocket server.

As far as I know, it does not need to be the same than the one on the site. You can check by entering here: http://vtortola.github.io/ng-terminal-emulator/ and executing the command websocket wss://echo.websocket.org, you will connect to a WebSocket in websocket.org that echoes your inputs.

WebSockets are not constrained by the SOP (Same Origin Policy), you can connect anywhere, and the server is responsible of checking the HTTP request header "Origin" and accept or refuse the connection.