Apple’s new iPhone X won’t be available until later this year, but the company is revealing a bit more information about how the facial recognition features of the new phone will work.
The company published a white paper Wednesday on Face ID security, alongside an update to its website’s privacy section. The paper answers a handful of the most pressing privacy and security related questions that people have had in the weeks following the iPhone X reveal.
So, uh, remind me — how does this thing work?
Every time you wake the iPhone X, it looks for your face. Next, it tries to confirm that your eyes are open and looking at the device — what Apple calls “intent to unlock.” Once that intent has been established, the phone’s TrueDepth camera system attempts to authenticate your identity by creating a model of your face.
First, a dot projector projects over 30,000 invisible dots of infrared light onto your face, which is read by an infrared camera and used to create a 3D image, or depth map. Next, the camera captures a separate 2D infrared image with the help of something called a flood illuminator, which is what helps the phone see your face in the dark.
These images are combined to create what Apple calls a “mathematical representation” of your face, which it compares to the model that was created when you first setup Face ID — after which the images are discarded.
What if someone makes a really good mask?
Apple says its put a handful of safeguards in place to prevent an unauthorized user from accessing your phone with a photo or mask. By matching against the 3D image of your face, for example, Apple says you can’t simply spoof the system with a 2D photograph, which doesn’t have any depth. And the company also says it’s trained a neural network dedicated to spotting spoofs — such as masks — though no additional information is provided.
And “to counter both digital and physical spoofs, the TrueDepth camera randomizes the sequence of 2D images and depth map captures, and projects a device-specific random pattern,” the white paper reads.
As a result of these and other measures, Apple claims that there’s a one in 1,000,000 chance that a random person could unlock your phone with their face (though Apple says this probability is “different” for twins and siblings, and doesn’t specify what that probability is).