A California consumer privacy group says it has cracked the once-secret code that allows law enforcement to track color printers by their printed pages.
The Electronic Frontier Foundation of San Francisco said it had cracked the code in a widely used line of Xerox printers. The code is an invisible set of dots that contain the serial number of the printer, as well as the date and time a document was printed.
With the Xerox printers, the information appears as a pattern of yellow dots, each only a millimeter wide and visible only with a magnifying glass and a blue light, the Washington Post reported.
The EFF said it has identified similar coding on pages printed from nearly every major printer manufacturer, including Hewlett-Packard Co.
The U.S. Secret Service acknowledged the markings, which are not visible to the human eye, are there, but it played down the use for invading privacy.
"It's strictly a countermeasure to prevent illegal activity specific to counterfeiting," U.S. Secret Service spokesman Eric Zahren said. "It's to protect our currency and to protect people's hard-earned money."
© Copyright 2005 by United Press International
