If someone severs your finger, they still can't unlock your new iPhone 5s

The introduction of the iPhone 5S and its easy to use fingerprint verification button has suddenly pushed biometric security into the mainstream. But for those with a little imagination, there are now concerns that smartphone thieves might soon resort to physically removing a person’s finger in order to gain access to a stolen device.

More broadly, some of the immediate concerns from the Apple community ranged from fears that, based on recent government surveillance revelations, the government might now collect all iPhone user fingerprints, to the notion that a person’s fingerprint might be lifted from a surface and used to hack into the device.

But neither of those concerns — at least one of which has since been dismissed as unfounded — resonated more than the frightening thought of having one’s hand physically mutilated in the course of being robbed of the new iPhone 5S. In recent years, such fears have been driven in part by reports like the one from Malaysia that detailed the theft of a biometrically secured Mercedes S-class car that resulted in the owner losing a finger so the thieves could start the car.

Now, after the Apple event dust has settled, biometric security experts have begun to weigh in and the overall verdict is: Your fingers are safe.  Now, after the Apple event dust has settled, biometric security experts have begun to weigh in and the overall verdict is: Your fingers are safe.

What we now know is that the iPhone’s Touch ID fingerprint sensor uses radio frequency scanning to detect the sub-epidermal layers of your skin, a dynamic that requires the owner of the finger to be alive and attached to the finger being used.

“The [RF capacitive sensor] technology is built in a way that the [fingerprint] image has to be taken from a live finger,” says Sebastien Taveau, chief technology officer at Validity Sensors, a California based provider of fingerprint sensor solutions. “No one in biometrics wants to talk about cut fingers and dead bodies, but at the end of the day we are still asked to remove the fears of consumer and make sure that they understand that [a severed finger] will not work.”

Of course, this new feature of the iPhone 5S doesn’t rule out instances of victims being forced to use their fingers to access the smartphone, but it does offer some comfort to those worried about worst-case scenarios.

For long-time observers of Apple this latest development doesn’t come as much of surprise, as it fits the company’s tradition of taking existing technology and mainstreaming it through innovation. “[Apple] used a technology that’s been around for a long time, but the big difference is that they made it cool," says Taveau. "It’s been around on laptops, but besides locking and unlocking your laptop there was not much of a use case for it.

"Now with Apple, by actually building an experience, they are educating the market, which is very important... Expect to see the Android world shipping [these kinds of] devices in the next couple of months.”