A report from four University of Washington researchers says Nike’s RFID-embedded shoe that links to an Apple iPod, using the $29 Nike + iPod Sport Kit, makes it easy for tech-savvy stalkers to track your movements, even plot your running routes on a Google map without your knowledge. Wired explains the Nike+ iPod gives runners real-time updates about the speed and length of their workouts. A small transmitter in the soles of Nike shoes broadcasts workout data to a small receiver plugged into an iPod Nano.

The RFID in the shoe sensor contains its own on-board power source, essentially turning your running shoe into a small radio station capable of being received from up to 60 feet away, with a signal powerful enough to be picked up from a passing car. Compare this with the roughly 3-centimeter to 10-inch read range of a typical consumer-grade RFID, such as the kind you find in smart tags in Gap clothing or in credit cards, which is passively powered by the reader. In their report, the researchers detail a scenario in which a stalker who wants to know when his ex-girlfriend is at home taps into her Nike+ iPod system. He simply hides the gumstix device next to her door, and it registers her presence as she passes by in her Nike shoes. If he adds a small “wifistix” antenna to the device, it can transmit this information to any nearby Wi-Fi access point and alert him to her presence via SMS or by plotting her location on Google Maps.