Quote:Researchers at Cambridge University have determined that attackers could use the built-in motion sensors in mobile devices to generate a unique device fingerprint.

Device fingerprinting has been in use for many years. It is the creation of a unique identifier, or fingerprint, through the combination of different bits of information made available by the target device. On desktop computers, this is largely through the browser. On mobile devices it is both through the browser and via apps.
 
There are some valid reasons for device fingerprinting. For example, the frequency with which a unique device connects or attempts to connect with a website could be indicative of attempted fraud. The primary use of fingerprinting, however, is to track users for marketing purposes, and is anathema to privacy activists and privacy conscious vendors. 
 
"A device fingerprint allows websites to detect your return visits or track you as you browse from one website to the next across the Internet," explains Alastair Beresford, a reader in computer security at the Computer Laboratory and an official fellow at Queens' College, Cambridge, in an associated blog. "Such techniques can be used to protect against identity theft or credit card fraud, but also allow advertisers to monitor your activities and build a user profile of the websites you visit (and therefore a view into your personal interests)."