The accelerometers in smartphones are great things - they change the orientation of the screen and let you play all kinds of cool games. But they're also big privacy risks. A researcher at Stanford has found that an accelerometer can help identify a smartphone - and its user.
Every accelerometer has defects. Usually the flaws are too small to notice, and they don't matter to the device's functioning. Each defect, though, is unique. That means every phone's accelerometer will generate slightly different numbers when the phone is standing still or when it moves.
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Hristo Bojinov, a security researcher at Stanford, found that a relatively simple program running on a website in the device's mobile browser can measure those defects, and come up with a "fingerprint" for the phone. He discovered the vulnerability while he was looking for ways to identify devices via their sensors, and his results will be published in the coming months.
Bojinov did an experiment where users visited a web site with their mobile devices, so they were willing participants. They were directed by the site to move the phone in a certain way. (You can visit the site at http://sensor-id.com/). The code on the site records the responses of the accelerometers.