Update: When asked about the intricacies of Face ID, Apple provided the following comment:
Our teams have been developing the technologies behind Face ID for several years, and our users’ privacy has been a priority since the very beginning.
Face ID provides intuitive and secure authentication enabled by the TrueDepth camera system and the A11 Bionic chip, which uses advanced technologies to accurately map and match the geometry of a user’s face. Face ID data never leaves the device, is encrypted and protected by the Secure Enclave.
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