There's a smart way to lock down iPhone X's Face ID instantly

Of all the new features on the iPhone X, one of the most discussed – and potentially misunderstood – is Face ID. Apple's new biometric security system had a rocky start, with exec Craig Federighi finding his demo handset had locked itself down after backstage staff inadvertently sent the face recognition into a panic when he tried to demo it at the launch event on Tuesday this week. However, despite some concerns, it seems Apple has put no small amount of thought into how Face ID will hold up in the wild.

The new system relies on the iPhone X's unique front-facing camera. Dubbed the TrueDepth Camera, it builds up a point cloud of the face and then makes a biometric "fingerprint" of sorts to identify the registered user. That way, Apple claims, it can keep track even as faces evolve gradually over time, such as if you change glasses, hairstyle, or even grow a beard.

The iPhone X will only unlock, so the theory goes, if the register user pays attention to it. That means not only must their face be in view, but their eyes have to be looking at the screen, too. It's a factor that led some to worry that thieves could snatch the handset, hold it up briefly to bypass Face ID security, and then escape with the $999+ device.

According to Federighi, however, there's a workaround to that, as long as you're on the ball. Developer Keith Krimbel emailed the exec with some questions about how Face ID works, and got a lengthy reply detailing some of the security considerations Apple has baked in. Most notably, Face ID can be temporarily disabled.

According to the message, should you be mugged, "if you grip the buttons on both sides of the phone when you hand it over, it will temporarily disable Face ID." The face recognition system will presumably need to be re-enabled by punching in the user's PIN or passcode. It's actually a similar issue to that which caused Federighi's demo glitch, though intentionally triggered rather than accidentally.

It's not the first time we've heard Apple has been baking in ways to instantly lock down your iPhone. Back in August, it was revealed that iOS 11 will support disabling Touch ID by hitting the power button rapidly five times in a row. After that, it'll take the PIN to re-enable fingerprint recognition.

Although this has clear uses if you're being mugged, there are also broader implications for times when your device might be of interest to law enforcement agencies. Currently, there's precedent for people using biometric security like fingerprint scanning to be compelled to unlock their device by court order. In contrast, courts have ruled against people being forced to enter their PIN.

Either way, you'll need to be quick enough making the trigger action to actually disable the biometrics. Still, if you're worried about your expensive new iPhone X being a potential theft risk, a surreptitious squeeze should be enough to keep your own face from giving the game away.