Use Google authentication token with Firebase

Question

I have a .NET application (not a web app) where users are already authenticated by Google Authorization, and therefore a token has been issued.

I'd like this application to store user data to Firebase with a user read-write security rule of type: "$user_id === auth.uid".

Since you may authenticate to Firebase with Google, is there a way that the application would pass to Firebase an already Google issued token?

Answer 1

The Firebase REST API only takes Firebase JWT tokens. You can take the information from the Google token and mint a JWT from it, using one of the libraries Firebase provides for the purpose.

This is covered in the User Authentication section of the Firebase documentation.