> Face ID data doesn’t leave your device, and is never backed up to iCloud or anywhere else. Only in the case that you wish to provide Face ID diagnostic data to AppleCare for support will this information be transferred from your device. Enabling Face ID Diagnostics requires a digitally signed authorization from Apple that’s similar to the one used in the software update personalization process. After authorization, you'll be able to activate Face ID Diagnostics and begin the setup process from within the Settings app of your iPhone X.
What is preventing the government from compelling Apple to give up this key, and intercept your diagnostic data?