Apple has released a white paper explaining some of the finer details of Face ID, the facial recognition system coming with the iPhone X. Much like Touch ID, Face ID stores only a partial version of your biometric data on the device, so even if an attacker extracted the data, they couldn’t reconstruct your face. Also, Face ID occasionally adds photos from successful logins to its model so it can continue to recognize you as your face changes over time. Unfortunately, Face ID may not be adequate to foil evil twins (we’re not kidding!). follow link
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Apple Documents Face ID Security Details