Visiting Facebook ID users without permission?

Question

I have a Facebook application (FBML). I do not want to click visitors to the application through the authorization process, however I want to know their Facebook identifier.

Is it possible to find a Facebook visitor on Facebook without having to "Authorize" my application?

Answer 1

Before that, I said that this is impossible, but it is possible.

http://developers.facebook.com/docs/authentication/canvas

Read that is great. You need to decode the Base64 string and verify that the signature is correct, but in addition it gets the user ID among other things (for example, the access token for the .facebook.com chart)

: "" ! , ...

, :)