Can Greasy Fingerprints on Smart Phones Give Away Passcodes?

That grease trail you’ve smeared on your smart phone’s touchscreen could give away more than your lightsaber skills or virtual girlfriend’s whims: Would-be smudge attackers, a recent paper argues, could follow your finger oils as a clue to your passcode.
In the paper “Smudge Attacks on Smartphone Touchscreens,” which we first saw on Gizmodo, a team in the computer science department at the University of Pennsylvania tried to pick out grease patterns from Android phones by photographing the phones and enhancing the patterns with photo-editing software. From the paper’s introduction:
“We believe smudge attacks are a threat for three reasons. First, smudges are surprisingly persistent in time. Second, it is surprisingly difficult to incidentally obscu...