Researchers in computer science and engineering at the University of Washington say "there are serious privacy breaches posed by the gadget."
 
"It is easy for someone to use the Nike+iPod as a tracking device," says lead author of the report, Scott Saponas. "It's an example of how new gadgetry can erode our personal privacy."

The kit is a wireless system (consisting of an in-shoe sensor and a receiver that attaches to the iPod) that allows Nike+ sneakers to talk with your iPod nano to track time, distance travelled, calories burned and average pace while you're running. The stats appear on your display or you can also hear the info with voice prompts via the headphones. Back at home, you can dock your iPod and upload your stats onto the nikeplus.com website to keep track of your times, set goals, compare results with other Nike+ runners worldwide and more.

The researchers created a variety of ‘homemade' devices that are able to pick up the sensor's unique signature. Each device uses the receiver sold with the kit and each was built for less than $300, they say. They reported that it took about "10 minutes to figure out how to decode a receiver's unique tag and a few hours to write the code that interprets the sensor data." They estimate that "an electronics hobbyist could build a system in a few hours, or at most a weekend. And if somebody posted sensor-scanning code on the Internet, it would be easy for others to build copycat devices."

The technical report says the device could be used in many scenarios such as a thief tracking when people leave their homes, or a jealous boyfriend could track a woman's movemnts, albeit at a close range. They tested out the technology to track each other's movements and those of colleagues on campus.

In the report, the authors suggest ways the company could have made the device more secure "using standard techniques from modern cryptography."

And for a start, the researchers suggest that people who own a Nike+iPod Sport Kit turn it off when they're not exercising so that it stops emitting signals.