When Apple first revealed the Touch ID fingerprint sensor, it was accompanied by a long and detailed explanation of how and where your fingerprint data is stored on the device -- in a special area on the iPhone 5s' A7 chip. But as iMore has discovered, locking your print details away in a dark corner of the processor isn't the only advanced hardware security measure that Apple has taken. It now appears that each Touch ID sensor is paired to its host device and won't respond if used elsewhere.
After being contacted by a third-party iPhone repair and modification company that was having an issue getting a replacement Touch ID sensor working on a new iPhone 5s, iMore did some testing. They discovered that each Touch ID sensor, though appearing identical on the outside, will only work with the phone it came with from the factory, suggesting an additional security layer that Apple decided to not to disclose.
But why pair the hardware components in such a way? Well, hackers are crafty, and while Apple insists that the fingerprint data is stored in a way that couldn't be reverse-engineered, if someone could tap into the conversation between the Touch ID and the A7 chip (possibly by spoofing the digital appearance of the Touch ID sensor) that information could be vulnerable. The chances that an individual could pull off such a feat is unlikely on its own, but by tying the sensor itself to one specific device makes it exponentially more difficult.