I just read Channels — Phoenix v1.6.5 again and some threads regarding the authentication in channels and now I’m confused.
As far as I understand it you should never expose authentication credentials to any part of a website that can be read by JS since an attacker could use this information to access your API. But in the docs it is described to render a Phoenix.Token into the site and use that to connect to the channel.
I understand that websocket connections are vulnerable to cross-origin attacks, so you cannot simply access the session.
And now I wonder how to do this securely? Because on one hand we cannot access the HTTP-Only session cookie and on the other rendering the Phoenix.Token would be vulnerable against cross site scripting if I’m not mistaken…
Also in LiveView I noticed that the second parameter for “mount” is actually
session. How is that implemented? Is that the reason, we have to pass a csrf token? Could this technique also be used in channels?