Fingerprinting does an OK job at biometric identification, but since our fingertips are usually coated with potato chip grease, we wouldn’t want to trust it for mission critical applications. A Japanese researcher thinks he has the solution — a unique mathematical "butt fingerprint" that could be used to protect your car against would-be criminals.

Associate Professor Shigeomi Koshimizu at the Advanced Institute of Industrial Technology in Tokyo uses a seat pressure map to generate a web of 39 indices that are used to uniquely identify a subject's rear end. Results so far have been encouraging, with average type one error (failing to correctly identify the driver's behind) of 2.2 percent, and type two error (mistakenly letting someone else drive away) of only 1.1 percent.

While biometric systems like facial recognition and fingerprinting are often dependent on environmental factors like lighting and the cleanliness of the sensors for success, Koshimizu hopes to leverage the relatively unchanging nature of the human buttocks to improve accuracy and lower the burden on the end user. On top of reducing car theft, he believes that the technology could be used in offices — to automatically log you in on your computer, for instance — or to generate a "foot map" as a key for accessing secure rooms or buildings.