EFF breaks Xerox DocuColor color printer tracking codes

Back in July I warned you about tracking codes that color laser printers embed on documents, ostensibly to help track counterfeiters, but in reality, who knows. The Electronic Frontier Foundation is reverse-engineering the codes, and announced today it had broken the codes produced by the Xerox DocuColor line of printers, commonly used in public copy and print shops.

The U.S. Secret Service admitted that the tracking information is part of a deal struck with selected color laser printer manufacturers, ostensibly to identify counterfeiters. However, the nature of the private information encoded in each document was not previously known.

“We’ve found that the dots from at least one line of printers encode the date and time your document was printed, as well as the serial number of the printer,” said EFF Staff Technologist Seth David Schoen.

You can see the dots on color prints from machines made by Xerox, Canon, and other manufacturers. The dots are yellow, less than one millimeter in diameter, and are typically repeated over each page of a document. In order to see the pattern, you need a blue light, a magnifying glass, or a microscope. . . .

“So far, we’ve only broken the code for Xerox DocuColor printers,” said Schoen. “But we believe that other models from other manufacturers include the same personally identifiable information in their tracking dots.”

You can decode your own Xerox DocuColor prints using EFF’s automated program.

Xerox previously admitted that it provided these tracking dots to the government, but indicated that only the Secret Service had the ability to read the code. The Secret Service maintains that it only uses the information for criminal counterfeit investigations. However, there are no laws to prevent the government from abusing this information.

“Underground democracy movements that produce political or religious pamphlets and flyers, like the Russian samizdat of the 1980s, will always need the anonymity of simple paper documents, but this technology makes it easier for governments to find dissenters,” said EFF Senior Staff Attorney Lee Tien. “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?” — Electronic Frontier Foundation

The last color document I printed was indeed political in nature. It’s frightening to think that it could be traced back to me by codes the manufacturer printed while I was busy printing my own document. This could have a greatly chilling effect on speech, not only in this country, but in others, where speech is even more restricted than it is in the U.S.

If you have a color laser printer, the EFF still needs your help to crack the codes. Specifically they need sample pages printed from your printer.