How could an iPhone tell it's being stolen?

Apple's Acceleration-based Anti-theft Device Idea

Accelerators measure motion over time, and this is key to how the Apple anti-theft idea works. It all begins with an acceleration sensor (which could be one or a group of accelerometers and the software required to make them work) continually monitoring the acceleration (motion over time) of your iPhone. Think of this as your phone getting to know you and how delicate or rough you are with it, the baseline acceleration signal for your phone.

That stream of data is filtered and compared to a series of characteristics known to happen in situations when theft is occurring; Apple has figured out that when a device is being stolen the data collected by the accelerometer -- the acceleration signal -- looks different than during those instances when the device is been dropped or during other types of everyday impact and usage. Apple calls these scenarios theft conditions, and there are filters designed to distinguish those frequency types and lengths from those in your baseline. For example, while you might like to run with your iPhone, characteristics of a theft condition might include frequencies that indicate running in addition to abrupt changes in direction or jumping movements.

Theft conditions are basic rules for when an alarm should sound (when someone snatches your phone and runs) or not (when your phone is jostled in your pocket). If the data matches characteristics of a theft condition, a signal is sent to the phone's microprocessor -- and that's the message the microprocessor needs to trigger the alarm to sound through the speakers.

While some may prefer to stick with the default settings, Apple's anti-theft device would allow users to edit their theft detection profile (as well as turn it on or off) through a user interface in their phone settings, including whether or not an alarm should sound during a theft, how loud the alarm should sound and also whether or not a message should appear on the device screen (and what that message should read). Users would also set a password to disable the alarm, as well as calibrate the sensitivity of their iPhone's theft detection system.

Despite how smart your phone may be, if it's slyly pocketed while your attention is diverted, don't rely on an alarm to sound. Chances are low it would be able to discern that kind of device-in-pocket motion as anyone other than you.

Author's Note

The first thing I thought of when I read through this patent application was, is Apple building the car-alarm equivalent for iPhones? And then I thought of how a good hail storm can set off a car alarm. What would the sensitivity of the iPhone alarm be, and how many people would be running to meetings with iPhone alarms sounding from their pockets as they go? While the technology doesn't yet exist (this patent was filed after the iPhone 5 was released), rest easily -- if this accelerometer-based theft device comes to pass, it sounds like there will be plenty of ways to adjust its sensitivity, or, just turn it off.

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More Great Links


  • Apple - iCloud. "Find My iPhone, iPad and Mac." (Nov. 9, 2012)
  • Cambell, Mikey. "Rise in Apple product theft accounts for over 14% of all major crime in NYC." Apple Insider. 2012. (Nov. 9, 2012)
  • Wehrenberg, Paul J. "United States Patent Application, No. 20120278907. Acceleration-based theft detection system for portable electronic devices." U.S. Patent and Trademark Office. 2012. (Nov. 9, 2012)
  • Winkler, Rolfe. "Fighting the iCrime Wave." The Wall Street Journal. 2012. (Nov. 9, 2012)

Wired UK. "iPhone Accelerometer Could Spy on Computer Keystrokes." Wired Science. Wired. 2011. (Nov. 9, 2012)