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.
We first heard about this problem a few weeks ago and have yet to find an answer. We think it’s worth telling our readers about it, especially if you plan to fix an iPhone 5s with a part bought from us at some point down the road. Here’s what you need to know:
The iPhone 5S Touch ID Home Button, and it’s sensor, is uniquely paired with each iPhone. For now, it looks like that means you will never be able to use another Touch ID sensor with your iPhone. When Apple revealed Touch ID, they said that the fingerprint data is stored safely in the A7 chip of the iPhone 5S. Now it appears that Apple does more than that and calibrates each sensor to work with one device.
What about a brand new iPhone 5S Touch ID Home Button?
We’re still trying to figure out why a brand new iPhone 5S Touch ID Home Button wouldn’t work. We can see why Apple would want to lock down a used one that was pulled from another phone… but why a brand new sensor? It seems that iMore only tested swapping sensors from one phone to another; we suspect it may be possible to put a brand new sensor into a used iPhone 5S.
Think of this theory as a permanent Bluetooth pair. Once you plug in a brand new sensor, it gets a code from the A7 chip in the phone. Unlike a Bluetooth device, the sensor cannot be re-paired with a new iPhone. We have a few sensors on order to test out this theory. We will report back with an answer to our theory in a future article.