To keep things short, I want to create a webpanel for user.
He links his client with website and now he has option to create his channel and change his groups etc. in the panel.

How to make the linking process secure and easy for the user?
Is pasting his UID good enough or create some one time code generation on website and he has to use that?

What are your thoughts? Maybe someone did something like this and want to share his/her experience with me?