How Does Touch ID Really Work?

Newer Apple devices like the iPhone 5S and the iPhone 6 allow users to unlock the Home screen with a fingerprint instead of a passcode. Those unfamiliar with the new Touch ID technology may wonder how it works and how secure it really is. What happens if your fingerprint won’t read? How likely is the sensor to break? Find out how it works and why it’s great.

What Touch ID Is


Image via Flickr by Janitors

Starting with the iPhone 5S, Apple has added Touch ID to the Home button of iPhones and iPads, taking the security measures of the passcode and making them more personalized. The Touch ID technology allows users to unlock their devices with a fingerprint instead of a passcode.

Fingerprints are far more unique than passcodes, and the print reader takes a fraction of the time necessary to enter a passcode.

Touch ID stores multiple fingerprints from the same user or from multiple users (up to five total), making it convenient for family and shared devices. You also have the option of setting up Touch ID for app and music purchase authorization in the Apple store.

What It’s Made Of

A sapphire glass lens sits on top of the Home button, protecting the Touch ID components beneath. Around it is a steel ring which helps detect your finger on the sensor. Inside is the sensor itself, which essentially takes a picture of your fingerprint, and a tactile switch. Then that fingerprint scan gets compared to mathematical representations of fingerprints stored within the phone, and if it recognizes you, you’re taken to the Home screen. This elegant and convenient process happens in a fraction of a second.

How It Captures Fingerprints

Iphone picture two

Image via Flickr by Janitors

The sensor in the home button has the ability to map fingerprints at 360 degrees. Once you’ve got your fingerprint in the phone, you can unlock it from any angle. It categorizes fingerprints into three types: loop, whorl, and arch. It also reads sub-epidermal skin, which means it’s not capturing the fingerprint on the outer layer of your skin, but on a living layer beneath, which makes it even more secure (though it’s hard to imagine someone using a fake fingerprint to try to unlock your phone!).

To add a fingerprint to your iPhone, go to Settings, Fingerprints & Passcodes, and Fingerprints. From there the phone will give you instructions which include touching the Home button several times with the finger you want to use, then moving the finger around to widen the internal picture. Every time you use the Touch ID on your iPhone 5S, the phone adds to the fingerprint it has on file, capturing even more detail. Even with a reliable and secure network like T-Mobile, your fingerprint images are never sent out, but stored only in your phone.

Why It’s More Secure

Touch ID users still need to have a passcode set in their devices. You only get five attempts to unlock your device with a fingerprint before it requires you to enter the passcode. You also must enter the passcode if you haven’t used your device for 48 hours, after restarting the device, or to load the Touch ID and fingerprint screens in the settings menu. Finally, if you lose your phone and lock it remotely, once you get it back you’ll have to enter your passcode to unlock it again.

Someone has a 1 in 10,000 chance of guessing your passcode. Those odds prove that the passcode is still a good way to protect your information, but there’s always the possibility that someone sees you enter it or that you’ve used a common one, like your birthday. Touch ID works in tandem with the passcode to keep your phone and your information safer. If the ease of access makes more people willing to use Touch ID than a passcode, that in and of itself makes Touch ID more secure than other phone locking methods and mechanisms.

Touch ID is one of the many things that make Apple devices so user-friendly. The temptation to leave your iPhone unprotected by a passcode to make it quicker to unlock is solved with the tap of a fingerprint. With Touch ID becoming standard on new Apple devices, your next Apple upgrade will have the same great security and convenience.


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