Check if Windows Live ID is valid

Question

I register new users to my app using their windows live id. How do I check if a Windows Live Id is valid, before I register the user.

Answer 1

Which type of Windows Live ID authentication are you using? Windows Live ID Delegated Authentication, Windows Live ID Web Authentication or RPS Server authentication?

Answer 2

 Windows Live ID Web Authentication 

Answer 3

I register new users to my app using their windows live id. How do I check if a Windows Live Id is valid, before I register the user.

I'm confused by this.  What do you mean by valid?  If a LiveID isn't valid, then you won't receive the login token.  Have you experimented with the samples for web authentication?

Answer 4

I want to check if a given Id is a Windows Live Id.

Answer 5

You should try working through the LiveID samples.  Once you understand them, the answer to your question should be obvious.

Answer 6

It just occurred to me that you might be asking how to check that the webauthtoken cookie has not been tampered with.  Is that what you're asking?

I'm no expert on the matter, but it appears that if you tamper with the webauthtoken using Firebug/Firecookie, you'll see errors such as this in VS's Immediate Window:

Error: u64: Base64 conversion error: ...
Error: DecodeToken: Attempted to decode invalid token.
Error: ProcessToken: Failed to decode/validate token: ...

You can follow along in WindowsLiveLogin.cs if you like.

I believe if you can decode webauthtoken without error, then the resulting WindowsLive.WindowsLiveLogin.User.Id is valid.  At least, I hope that would be the case.