That page doesn't say that, and "tied to the phone number" sounds like they will only give you the key if you can authenticate via SMS.

Do you have a better cite or did you check directly recently?

I'm sorry, but where did you get that information from? The FAQ only states:

> Media and messages you back up aren't protected by WhatsApp end-to-end encryption while in Google Drive.

That makes sense, why would you re-encrypt the messages with the end-to-end-key which is individual for each chat, if you could simply use a symmetric encryption for backups?

So the statement

> It is encrypted with a per user key known to WhatsApp.

could still hold true, there's no information contrary to that in the FAQ (but no information indicating another kind of encryption either).