Patent ID: 7299503

Claim:
A method of authenticating a data processing device, comprising: receiving an electrical signal having a data signal added therein, wherein the electrical signal is indicative of a location of the data processing device; extracting the data signal from the electrical signal; comparing data of the data signal to security information stored in the data processing device; and permitting operation of the data processing device based on the comparison of the data of the data signal to the security information, wherein the method further comprises: receiving a data packet from a sending device via a data network, wherein the data packet includes a first data value and a first timestamp associated with the first data value; querying a history data structure for a second data value associated with a second timestamp in the history data structure based on the first timestamp; comparing the second data value to the first data value; permitting processing of the data packet if the second data value matches the first data value; adding an identifier of the sending device to a list based on the comparison of the second data value to the first data value, wherein if the second data value matches the first data value, the list is a list of authorized devices, and wherein if the second data value does not match the first data value, the list is a list of unauthorized devices; and periodically clearing the list of authorized devices and the list of unauthorized devices.