The key could be added to the appleid on the server, without telling the phone about it. Others sending messages to you would then also encrypt with the new bac

The key could be added to the appleid on the server, without telling the phone about it. Others sending messages to you would then also encrypt with the new backdoor key. Likewise, you don't get notifications about your friends' keys updating (in fact there's not even any UI to show the current keys for a contact), so your phone would start encrypting messages to the recipient's additional backdoored key silently too. :(