The design of the Nike+iPod Sport Kit leaves it vulnerable to potential surveillance of the wearer, according to a team led by University of Washington doctoral student T. Scott Saponas. Their research report describes the potential for privacy and personal security problems if the transmissions of the in-shoe sensor are intercepted. The sensor is designed to transmit a unique code, identifying the shoe and therefore its wearer, to an iPod. The wearer may not realize that the sensor is normally on (it can be switched off), and that another person or monitoring system could track their location from as far as 60 feet away. The report describes demonstration systems that Saponas and his research partners set up. One such system monitors the signals, identifies the wearer by the unique code, and uploads the data to a server that uses Google Maps to pinpoint and track the wearer's location in real-time. According to the report, the Nike+iPod designers could have used simple cryptographic techniques to avoid or lessen these potential problems.