iPhone 5s full review

We continue our in-depth iPhone 5s review with a look at security.

iPhone 5s review: security and the Touch ID fingerprint scanner

If you are looking for a new phone the security features should be an important part of the decision. Your phone is one of the most valuable products you will have in your possession at all times. Consider what would happen if it fell into the wrong hands. Would someone be able to access your email, Facebook, your bank account? Apple has endeavored to improve security of the iPhone in a number of ways over the years.

For example, back in June 2010 the company introduced Find my iPhone, a tool that enables you to look up the location of your iPhone on the web or in an app and wipe it so that your personal information can't fall into the hands of criminals.

Apple has gone one step further to secure your iPhone with the iPhone 5s. When it comes to technical innovations, the iPhone 5s can boast two major breakthroughs and one of these breakthroughs is the Touch ID fingerprint sensor.

For convenience and simplicity, securing your phone by that most familiar of unique identifiers – the fingerprint - would seem to be a logical next step in smartphone technology. And yet, when Apple added the technology no other company had successfully staked fingerprint recognition on its phones – attempts by Motorola and LG were pretty poor, hindered by such poorly thought out ideas as placing the reader on the back of the phone.

In the months that followed the iPhone 5s launch some smartphones have gained similar fingerprint recognition such as the Samsung Galaxy S5's fingerprint-based authentication system for which PayPal already has an accompanying app.

The surprise was that Apple didn't add Touch ID to the iPads that launched in October 2013.

The Touch ID fingerprint sensor in the iPhone 5s is the result of Apple's purchase of biometric specialist AuthenTec back in 2012.

Using the Touch ID fingerprint scanner

iPhone 5s review: How Touch ID works

Unlike the awkward print readers beloved of Windows laptops, which might unlock one time in three attempts, and require you to carefully stroke your fingertip along a narrow scanner, the Apple reader is a capacitive touch sensor which is defined as: "A touch screen technology that uses a uniform electric field across a transparent conductive layer. When a user's finger touches the layer, the measured amount of current drawn from each corner is used to calculate the location of the touch."

This sensor is only 170 microns thin (thinner than a strand of hair), and takes a high-resolution (500ppi) picture of the sub-epidermal layers of your skin and then compares it to the fingerprint it has on file for you. In essence Apple has turned the home button into a very high-resolution camera.

The Touch ID sensor is covered by a sapphire crystal lens that Apple claims protects the sensor and acts as a lens to focus it on your finger. Apple describes sapphire as “one of the clearest and hardest materials available.” This acts as the lens and home button.

This is surrounded by a steel ring that detects your finger. On the gold and silver iPhone 5s the ring matches the device's colour. On the Space Gray iPhone the ring is black so it doesn't really show up.

Read more about How Touch ID works here.

The parts of the Touch ID scanner

iPhone 5s review: How to use Touch ID

Thanks to Touch ID when you touch your finger to the Home Button on the iPhone 5s your phone unlocks. This means the four-digit PIN number is no longer necessary to unlock the iPhone thereby speeding up access to a locked phone, or at least making access simpler. We think this is a feature targeted at those people who don't have a passcode because they are too lazy to use one. Before the iPhone 5s launched Apple estimated that only half of all iPhone users used a passcode. Apple's webpage on Touch ID security indicates that the introduction of Touch ID was designed to encourage more people to secure their iPhone.

Actually the passcode is still required after you have turned the phone on and off and in various other circumstances that we will detail below.

You need to spend some time setting up the iPhone 5s to recognize your fingerprint. When doing so you should bear in mind that some people have had issues using Touch ID on their iPhone 5s, although the iOS 7.1 is said to have improved accuracy. While the scanner may be to blame, we think it's more likely to be user error. The best way to ensure that you don't have issues with Touch ID is to be careful when you set it up.

To set up Touch ID go to Settings > Touch ID & Passcode, then enter your Passcode if you have on set up, and tap Add a Fingerprint… Now the iPhone will take you through the set up process. There's a lot of dabbing – if you dab too quickly you will get told to slow down. It will also tell you not to move your finger too much between scans. It's best to wait for the phone to vibrate before moving your finger again. Then the phone will ask you to adjust your grip so it can scan the edges of your print. After a couple of minutes of this you will be ready.

Setting up Touch ID

Follow these tips to get the most out of Touch ID.

1) Take time to get a good scan: it takes a while to set up scans for fingers, so don't try and cut corners because you are busy. You need to move your finger around multiple times and as you do so you will see an image of a fingerprint with the various lines being filled in. When you think you are done Apple asks you to scan the edges of your finger, to make absolutely sure the Touch ID sensor has as much data as possible. If you rush things it's likely that you will find that sometimes your fingerprint doesn't unlock your phone.

2) Scan your finger in the way you would hold your phone – it stands to reason that the fingerprint 'seen' by Touch ID when you are holding the phone will be different to the fingerprint 'seen' when you have the phone in front of you on your desk. So don't scan your fingerprint in a way that you would never use it. For example, if you tend to use the tip of your finger when you press the home button make sure you scan that part of your finger.

3) Scan more than one finger - one reason it's worth setting Touch ID to recognize more than one finger is that you might cut or burn your finger. If you have more than one finger set up you can switch fingers.

4) Touch the ring - when you are scanning you should make sure that you are touching the metal ring around the edge of the Home Button because that ring helps the scanner to recognize the print. It's not there for looks.

5) Don't use wet fingers – whether setting up Touch ID or using it later on make sure your fingers are dry. Similarly don't expect Touch ID to work when you are just out of the bath and your finger is all wrinkled.

Using the Touch ID fingerprint scanner

Once Touch ID is configured you need only lay your finger on the opaque glass window momentarily, and the Touch ID sensor does the rest for you. The iPhone 5s will only respond to the print of the owner (or someone else if you wish to give up one of your allocated five fingers to a partner).

When we say momentarily, it's not completely instantaneous. We sometimes wonder if it wouldn't be quicker to enter our four-digit passcode.

If Touch ID does not recognise your finger it'll give up after a couple of tries and flip over to reveal the passcode. You can use this to unlock the phone instead.

Once you have set up Touch ID you can use any of the fingerprints stored on your iPhone to unlock it. It doesn't have to be fingerprints either. We've heard of people using a toe, or even a cat's paw. Now,  rather than enter your four-digit PIN code, you can touch and hold the home button and after a few seconds the phone will unlock. When we first started using Touch ID we kept pressing and holding the home button, which, of course, called up Siri. We eventually trained ourselves out of that habit.

If Touch ID doesn't work after three attempts it will switch to your Passcode screen.

Read our article about how to set up Touch ID on your iPhone 5s. 

iPhone 5s review: For what can you use Touch ID?

Once it's set up you use the sensor to unlock your iPhone, and you can also use it to authorise purchases from iTunes Store, the App Store and the Apple BookStore.

In our time with the iPhone 5s we have found this feature one of the most useful. The first time we made a purchase from iTunes we had to enter our password, but after that one time we were able to use Touch ID every time we wanted to make a purchase - no more tapping in of complicated passwords. Hooray!

Using the Touch ID scanner to purchase from iTunes

Touch ID can't currently be used by third party apps. It is likely that Apple decided not to give third-party access to your fingerprint information for security reasons, but it is a shame that, at least for now, we cannot use our fingerprint to unlock the ability to pay for something on Amazon or eBay in the same way as we can on the App Store.

Nor can you use Touch ID to access iCloud Keychain, which is a key feature of iOS 7. This may concern you because, presuming that your finger print is harder to guess than your passcode, this in effect leaves all your passwords, and even your credit card details vulnerable should someone be able to hack your passcode.  This is essentially the problem with Touch ID – if you get it wrong you can still unlock the iPhone using the passcode, so keep that away from prying eyes.

Nor can you use both a fingerprint and a PIN to create a two-factor authentication system, which might be the next step for the particularly paranoid.

iPhone 5s review: Is Touch ID secure?

Like most security systems, Apple's Touch ID can be defeated by some long-winded and careful preparation, as demonstrated by a German computer club days after launch. The resources and skill to do so are not trivial.

If you are wondering whether someone could cut off your finger and use that to unlock your phone, fear not. Apparently the finger needs to be live in order for Touch ID to work, we're not sure how this was tested though…

As for whether someone else might have the same fingerprint as you – the probability of this happening would be 1 in 50,000 according to Apple. And the probability of that person actually having access to your phone: You'd need an infinite improbability drive for such an occurrence.

As for whether your fingerprints are secure – Apple says it doesn't store images of your fingerprints. It stores only a mathematical representation of your fingerprint. So, don't worry, NSA won't be able to get their hands on it. For reassurance, Apple notes: "All fingerprint information is encrypted and stored securely inside the Secure Enclave inside the A7 chip on the iPhone 5s: it's never stored on Apple's servers or backed up to iCloud."

So, we can safely say, for most daily use the Touch ID system should prove a useful and effective way of locking down your phone. (Read more about how secure Touch ID.)

Turn to page 3 of our iPhone 5s review to find out about the iPhone 5s processor and the results of our benchmark testing >>

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