Apple's Touch ID fingerprint sensor explained: Here's what you need to know

Apple's iPhone 5S looks nearly identical to the iPhone 5 apart from new colour options and a slim steel ring around the Home Button. But this ring isn't just for aesthetics. It detects fingerprints and alerts a new technology - called Touch ID - to scan, read and recognise fingerprints.

While celebrated as one of the headlining features of iPhone 5S, Touch ID is also causing many to furrow their brows over security concerns. Something that can capture fingerprints, unlock iPhones and authorise App Store purchases might be frightening to some, but it's a game-changing advancement that potentially saves time and paves the way for more innovation.

So, before you dismiss iPhone 5S and Touch ID, read what Pocket-lint has compiled below. It's everything you need to know and more.

1. What is Touch ID?

Apple has embedded a fingerprint sensor into the iPhone 5S's Home Button as a way to bypass the lock screen's passcode and do away with Apple ID passwords. It has called this innovation "Touch ID".

Touch ID is just a brand name created by Apple. It stands for the Home Button's fingerprint sensor and the technology used to read and recognise fingerprints. Since Touch ID is both new hardware and software from Apple, it's only available on the iPhone 5S.

Apple's premise behind Touch ID is simple: a fingerprint is one of the best passwords in the world because no two are alike and it's always with you. Therefore, the company thinks it is an ideal way to make iOS devices easier to use as well as more secure.

2. What tech is behind Touch ID?

The Home Button is made from Sapphire Crystal, and it protects a 170 microns-thin sensor underneath. The Home Button also doubles as a lens, allowing the 500-ppi sensor to focus on your fingerprint.

The steel ring around the button is what detects your finger and notifies Touch ID to start reading your fingerprint, while the sensor uses advanced capacitive touch to capture high-resolution images of your fingerprint.

As for software, Touch ID reads fingerprints in 360-degrees of orientation, analyses the sub epidermal layers of the skin and categorises each fingerprint into arch, loop or whorl categories.

Touch ID will then map individual details of fingerprint ridges, including variations like pores, and compile all of the data together. Touch ID uses this data to match and recognise fingerprints.

3. How do you set up Touch ID?

It's simple, actually. Go to Settings > Passcode & Fingerprint > Fingerprint. From there, choose “Add a Fingerprint".

An on-screen prompt will then guide you through the fingerprint-scanning process. Touch ID will want to scan all the angles and unique identifiers of your fingerprint. All you need to do is keep touching the Home Button.

Once finished setting up, Touch ID will continue to learn your fingerprint every time you touch the Home Button. It even gets better at reading fingerprints and can recognise them in any orientation. It'll also read up to five fingerprints (which is handy for families using the same account/device).

You'll need to set up a passcode to configure Touch ID. Apple said Touch ID will minimise the input of your passcode, though a passcode is still required for additional security. You could alternatively set up a complex alphanumeric passcode.

4. How does Touch ID work?

Just touch the Home Button. The Touch ID sensor will read your fingerprint. Upon reading your fingerprint, Touch ID will automatically unlock a passcode-enabled iPhone 5S.

Touch ID can also authorise purchases in the App Store, iTunes Store and iBook Store. Just tap the "buy" button for any song, app, book, movie, etc., and your iPhone 5S will immediately prompt you to touch the Home Button.

Similar to how it unlocks a passcode-enabled iPhone 5S, the Touch ID sensor will read your fingerprint and authorise purchases. You will have to scan your fingerprint with each purchase. However, after five failed attempts, iPhone 5S will ask you to enter your Apple ID password.

5. Is Touch ID secure?

All fingerprint information is encrypted and stored in Apple's new A7 chip. Touch ID doesn't store any images of fingerprints, but it does store "mathematical representation" of fingerprints. Apple said it is not possible for a fingerprint image to be "reverse-engineered" from this mathematical representation.

The iPhone 5S also features an advanced security architecture - called the Secure Enclave - within the A7 chip that protects and verifies fingerprint matches. Apple said the Secure Enclave is "walled off from the rest of A7 and as well as the rest of iOS", meaning only Touch ID has access to fingerprint data. It's not available to other software, stored on servers or backed up to iCloud.

Touch ID is also not available to third-party app developers - at least initially. So, it's going to work only on lock screen passcodes and Apple ID passwords. More information about Touch ID security is available on Apple's dedicated support page.

6. Will Touch ID recognise toeprints?

Yes. You can use your toes to open the new iPhone 5S. Read more about it at Pocket-lint.



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