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Just because a document from a color laser printer doesn't carry your
name doesn't mean no one can trace it back to you, privacy advocates warn.
The Electronic Frontier Foundation says it has cracked the tracking
codes embedded in Xerox Corp.'s DocuColor color laser printers. Such codes are
just one way that manufacturers employ technology to help governments fight
currency counterfeiting.
"Underground democracy movements ... will always need the anonymity
of simple paper documents, but this technology makes it easier for governments
to find dissenters," said Lee Tien, EFF senior staff attorney. "Even
worse, it shows how the government and private industry make backroom deals
to weaken our privacy by compromising everyday equipment like printers."
Researchers found patterns of yellow dots arranged in 15 by 8 grids and printed
repeatedly over every color page, said Seth Schoen, a staff technologist at
the San Francisco-based civil-liberties group.
The dots are visible only with a magnifying glass or under blue light, which
causes the yellow dots to appear black.
By analyzing test pages printed out by supporters worldwide and by staffers
at various FedEx Kinko's locations, researchers found that some of the dots
correspond to the printers' serial numbers. Other dots refer to the date and
time of the printing.
Xerox spokesman Bill McKee would not provide details about the technology.
He said the company "does not routinely share any information about its
customers," though it does respond to requests from law enforcement.
At the Secret Service, which helps develop such technologies with other government
agencies and industry, spokesman Eric Zahren said the tools are designed "simply
to make it more difficult to utilize that equipment for the illegal activity
of reproducing genuine U.S. currency."
"They do not in any way track the use of a personal computer or a person's
computer's hardware or software," he added, refusing to elaborate on the
technologies.
But Schoen said much can be gleaned from the printouts alone.
Consider two documents, one carrying the author's name and one meant to be
anonymous. By comparing the codes, it can be determined whether the two documents
came from the same printer, even if Xerox reveals nothing about a customer's
serial number, Schoen said.
The EFF is now studying other printers from well-known manufacturers with similar
tracking codes, but whose keys remain secret.
The Xerox DocuColor printers are high-end machines more likely to be found
in offices and copy centers than in homes.
The U.S. government is involved with other countries in a separate anti-counterfeiting
program meant to prevent currency from being scanned and printed.
Adobe Systems Inc. has acknowledged quietly adding the government software
to its Photoshop software at the request of regulators and international bankers.
But David Skidmore, a spokesman at the Federal Reserve Board, said that the
technology, known as the Counterfeit Deterrence System, was aimed mostly at
personal computers and ink-jet printers — not the high-end machines like
DocuColor.