Everyone was concerned about the iPhone 5S’ fingerprint sensor collecting data, such as our fingerprint images. Then people worried about the NSA collecting that information. However, as we heard during Apple’s conference, that data is not stored remotely. It’s stored directly on the iPhone.
There’s more to that. According to the Wall Street Journal, which spoke to an unnamed Apple spokesperson, it will only collect “fingerprint data,” not your fingerprint image. This means that if someone does manage to work their way in and hack your iPhone, and crack the encrypted chip, it’s still very unlikely that they could “reverse engineer someone’s fingerprint.”
You will also be required to create a passcode. For one, if you’re worried about the fingerprint thing. Two, and more importantly for the rest of us, in case you injure (cut) your finger, or the sensor is dirty, etc. You can simply use the passcode unlock. The passcode is also required if you reboot your handset or haven’t unlocked it within 48 hours. This is also a security feature that helps “block hackers from stalling for time as they try to find a way to circumvent the fingerprint sensor.”