revoke GCM Server Key after migration to FCM

Question

I'm planning my project's migration from GCM to FCM.

An experienced FCM person says:

... after importing the project to Firebase, it would generate its own Server Key that you could use [in FCM legacy API calls to push to devices with GCM-generated tokens and FCM-generated tokens]

With this new Firebase Server Key I would no longer need the old GCM Server Key. Because the old GCM key won't be necessary I'd like to revoke it to limit possible attacks. Is it possible to revoke all old GCM Server Keys for a project after migrating the project to FCM?

Answer 1

It's possible. GCM Projects were provided Server Keys that are accessible via the Google Developer's Console (make sure you select the correct project).

From the screenshot above, you could see Server key (auto created by Google Service). The option to delete the API Key can also be seen here -- the trash icon is beside the copy icon.

If you already imported the project to Firebase, navigating to the Cloud Messaging tab would also show the old Server Key, aka the Legacy Server Key.

Choosing to delete the default Server API Key will show the following prompt:

This credential will be deleted immediately and permanently. Once deleted, it can no longer be used to make API requests.

Do you want to delete the credential?

Proceeding to delete the key, then refreshing both pages afterwards, would show a new auto created Server Key.