Apple's new Face ID technology only appears in the iPhone X flagship. This replaces Touch ID on this device, instead of unlocking the phone via facial recognition. This has raised concerns among users who have become accustomed to the speed and reliability of Touch ID and have seen similar facial recognition technologies fail. While the technology behind Face ID isn't new or revolutionary, Apple says it's better implemented than ever.
ContentsHow Face ID works?What about sunglasses, beards and darkness?Is Face ID secure?Will Face ID replace Touch ID?
The infrared light used by Face ID is invisible to humans, but it works much like normal light. However, since its frequency is lower than that of ordinary light, it finds it a bit easier for it to pass through certain objects. This includes things like sunglasses which are generally balanced to block visible and ultra-violet (UV) light. This light exists at the opposite, high-frequency end of the visible light spectrum. As a result, most sunglasses let infrared light through. This allows Face ID to preview even when sunglasses obscure your face.
The vaunted A11 Bionic chip in the iPhone X supports machine learning, allowing Face ID to adapt to changes in your appearance. If you grow a beard, cut your hair, or put on glasses, Face ID should track the changes. We'll have to see the success of this feature in practice, but if it works as advertised, it will be a major step forward in the usefulness of facial recognition.
Infrared light also allows Face ID to work in the dark. Since the camera provides its own light source in the form of an infrared beam, the system does not need external light sources to operate. It can also use the flood illuminator (essentially an infrared flash) to balance and normalize the lighting on your face. And because this infrared light is invisible to humans, there will be no flash of light. This means that even in total darkness or uneven lighting, the iPhone X should be able to correctly identify your face.
According to Apple, Face ID avoids common spoofing attacks that made other face unlock systems insecure. Because it uses a depth-sensitive infrared camera, attackers cannot fool the camera with a photo. Even three-dimensional masks apparently failed to fool Face ID.
Although methods to avoid three-dimensional spoofing have not been published, infrared light can penetrate the skin, allowing the TrueDepth camera to scan subcutaneous features that would be difficult (or even impossible) to reproduce for mask makers. We can also assume that the thousands of facial recognition points make it difficult to create a mask with enough fidelity to fool the TrueDepth camera.
Like Touch ID fingerprints, the mathematical models of recognized faces remain in the iPhone X's secure enclave. They are encrypted, inaccessible to other apps and much of the operating system, not to mention attackers. Recognized faces only exist on the device and are not stored on Apple servers or synced to iCloud. And as far as we know, Secure Enclave has not yet been compromised.
According to Apple, Face ID's error rate is 1 in 1,000,000. That means Face ID could unlock for the wrong person once in a million attempts. Touch ID had an error rate of 1 in 50,000, which makes Face ID more accurate by orders of magnitude. And just like Touch ID, Face ID can also authenticate Apple Pay. Does this mean Face ID will eventually replace Touch ID? If it turns out to be as simple and reliable as Apple claims, it just might.
