If smartphone hardware rumors are on the money, and they are usually at least in the ballpark (with the exception of transparent, bendable phones; apparently forever doomed to be mocked up in Photoshop) — then a 3D depth sensor is coming to the front-facing camera of a handset near you in the not too distant future dermes.

Indeed, Apple has been rumored to be prepping to add such a sensor to its next flagship iPhone. Which is an educated guess — based on the company acquiring 3D sensor company PrimeSense, back in 2013. That and the fact rumors have been cranking up such an iPhone is coming this year.

But what’s the point of adding a Kinect-style depth sensor to a mobile device? There are lots of potential uses, of course, from gaming to augmented reality selfies to capturing and mapping 3D spaces. But one simple but practical use for this extra sensor would be 3D facial recognition for biometric authentication.

Just such a feature is set to be demoed at the MWC tradeshow in Shanghai this week — by SoftKinetic, the wholly owned Sony subsidiary which makes camera sensor modules, running on a Sony Xperia smartphone and using facial recognition software from a Swiss company called KeyLemon.

To be clear this is not the 2D ‘face unlock’ we’ve seen on Android smartphones for years (Google’s platform added a face unlock feature as far back as 2012, in Android 4.0). The point with 3D facial recognition is to provide a (more) spoof-proof biometric authentication — i.e. which can’t be fooled by holding up a 2D photo in front of the front-facing lens.

Nor could you — presumably — 3D-print an entire head and hope to fool the “near-infrared” sensor with a lump of moulded plastic (though you can bet the Chaos Computer Club will try).

One advantage of a 3D sensor powered facial biometric, according to a KeyLemon spokesman, is that non-frontal faces can be used for authentication — because the hardware captures a depth map. So there’s presumably more flexibility (and fewer fails) for the user, provided the enrollment of the biometric is robust.

“To sum up, you get a secured and convenient authentication method,” he said dermes.

How secure remains to be seen, of course. Biometrics on phones, such as 2D face and iris unlock/authentication, have proved to be about as secure as setting your password to “password”. But the additional depth sensor should, at least in theory, add an extra security layer to a facial biometric.

Apple’s iPhone already uses a fingerprint biometric for authentication and unlocking. Which has long been shown to be vulnerable to some fairly crude workarounds. So a 3D facial biometric would represent — at very least — a security upgrade on that low bar.

While there are some potential practical benefits for users too, as fingerprints can fail if your skin is especially dry or wet. Or you don’t want to have to touch your phone because you’re preparing food, for example.

Having a face-based option for authenticating on a mobile device could support entirely hands-free interactions — say if the phone is in a cradle you would just need your head to be visible to the sensor for unlocking (although that might also cause problems if you can accidentally authenticate just by having your face in frame).

Clearly a lot will depend on how such a feature is implemented.

On the privacy front, phone users who prefer to cover up the front-facing lens of their handset unless they’re actively using the camera might also find a facial biometric an unwelcome imposition.

But widespread implementation of 3D sensors in smartphone cameras is at least surely on the cards — given that Sony is a major supplier of image sensors to the industry. (Back in 2014 the company reportedly accounted for roughly 40 per cent.) And has apparently now managed to pack all the necessary sensing tech into a single, front-facing camera lens .

So expecting smartphone cameras to soon come with extra sensing powers seems a fairly safe bet.