Civil liberties group cracks the print surveillance code

The US Secret Service has conceded the tracking information is part of a deal struck with selected colour laser printer manufacturers, as part of efforts to identify counterfeiters. The nature of the private information was not previously known, but EFF has discovered dots that encodes the date and time the document was printed, as well as the serial number of the printer.

Seth David Schoen, staff technologist at EFF, claims his organisation has broken the code for Fuji Xerox's DocuColor printers. “But we believe that other models from other manufacturers include the same personally identifiable information in their tracking dots,” he says.

Lee Tien, senior staff attorney at EFF, claims the technology makes it easier for governments to keep tabs on dissenters. “Even worse, it shows how the government and private industry make backroom deals to weaken our privacy by compromising everyday equipment like printers.

“The logical next question is: what other deals have been or are being made to ensure that our technology rats on us?” says Tien.

Dots on colour prints have so far been identified on machines from Xerox, Canon, and other manufacturers. The dots are yellow, less than one millimetre in diameter, and are typically repeated over each page of a document. The patterns can be viewed with a blue light, a magnifying glass or a microscope.

For a list of the machines investigated so far, visit www.eff.org/Privacy/printers/list.php , and for instructions on how to view the dots visit www.eff.org/Privacy/printers/docucolor. Fuji Xerox's DocuColor prints can be decoded using EFF's automated program at www.eff.org/Privacy/printers/docucolor/index.php#program.