Wesley's Tool-Box

There has been some talk about the sensor (accelerometer, gyroscope, and compass) readings of iPhone 5S being inaccurate, and since those are handled by M7, some are blaming the chip for the problem. I can't verify this claim, but I have multiple iPhones, so I can tell you if iPhone 5S strays far from the norm.

First of all, the compass seems to be doing fine. As you can see here, 5S is getting the same reading as 5, and not far from 4S's. As I moved these devices around, the readings from 4S, 5, and 5S were basically within 5 degrees of each other. 3GS was the actual standout, giving noticeably different readings from the rest of the devices. This could be due to the device's old age.

I should note that putting two phones close to each other, as some people have done to show the differences, is not a good idea. The phones affect each other's magnetic readings from the electromagnetic noise that they generate, making both units' compass deviate. It's akin to putting a magnet next to a real compass. This is why I gave the phones a bit of room. I would disregard any reports of compass error that show the photos of phones being right next to each other.

But what about the measurement of tilt as detected by gyroscopes and accelerometers? Let's take a look at those, too.

Probably the biggest new feature in the iPhone 5S that is completely hidden to an outside observer is Apple M7 (NXP LPC18A1), the motion coprocessor that handles a variety of sensor inputs (accelerometer, gyroscope, and compass) independent of the main processor, A7. Its main potential use is for health and fitness apps, and rightly so, they are the first apps to take advantage of it. Argus (Sept. 20) and Strava Run (Sept. 24) were updated right after iPhone 5S release to use M7. I see it as a big feature because this would enable a lot of apps to poll sensor data without draining battery much at all.

Interesting enough, when you run an app with M7 support, you'll be asked to allow access to motion activity. This is a good sense on Apple's part because these data can be easily used to track user's habits. GPS data merely tells you that a person was there. Motion activity data tells you how you were moving around there very precisely. Let's take a more careful look.

Apple acquired AuthenTec back in 2012, and a lot of rumours circulated about the possibility of iPhones using fingerprint sensors created by this company. Come 2013, this has come true in the form of an integrated fingerprint sensor called Touch ID on the home button of iPhone 5S. In the process, the iconic rounded square marking in the button was sacrificed in the name of progress. The physical button is still clickable as always. The sensor works only when you leave your finger on the button without clicking.

Many experts view biometric authentication such as fingerprint scanning as a good way to "augment" security. It is by no means a complete replacement for existing measures because you can't change your biometric characteristics, and the detection can be fooled with sufficient resources and will. So it's generally recommended that this is used in conjuction with another authentication method such as ID & password. That said, Apple has decided that it's good enough to be used as an alternate method of entering passcode for unlocking lock screens.

This doesn't sound good from strict security standpoint because the biometrics are used to "replace" rather than "augment". However, Apple's rationale is that a large number of people don't even set passcodes, and by providing this alternative in a convenient package, phones would be somewhat secure, than not secure at all. Then, the convenience angle must be sufficiently strong to gain traction.

Using this feature for some time, I can say that this would indeed be the case. Read on to see my demonstration.