Sleuths Crack Tracking Code Discovered in Color

[ via an email fw ]


It sounds like a conspiracy theory, but it isn't. The
pages coming out of your color printer may contain
hidden information that could be used to track you
down if you ever cross the U.S. government.

Last year, an article in PC World magazine pointed out
that printouts from many color laser printers
contained yellow dots scattered across the page,
viewable only with a special kind of flashlight. The
article quoted a senior researcher at Xerox Corp. as
saying the dots contain information useful to
law-enforcement authorities, a secret digital "license
tag" for tracking down criminals.

The content of the coded information was supposed to
be a secret, available only to agencies looking for
counterfeiters who use color printers.

Now, the secret is out.

Yesterday, the Electronic Frontier Foundation, a San
Francisco consumer privacy group, said it had cracked
the code used in a widely used line of Xerox printers,
an invisible bar code of sorts that contains 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 EFF said it has identified similar coding on pages
printed from nearly every major printer manufacturer,
including Hewlett-Packard Co., though its team has so
far cracked the codes for only one type of Xerox
printer.

The U.S. Secret Service acknowledged yesterday that
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," agency spokesman
Eric Zahren said. "It's to protect our currency and to
protect people's hard-earned money."

It's unclear whether the yellow-dot codes have ever
been used to make an arrest. And no one would say how
long the codes have been in use. But Seth Schoen, the
EFF technologist who led the organization's research,
said he had seen the coding on documents produced by
printers that were at least 10 years old.

"It seems like someone in the government has managed
to have a lot of influence in printing technology," he
said.

Xerox spokesman Bill McKee confirmed the existence of
the hidden codes, but he said the company was simply
assisting an agency that asked for help. McKee said
the program was part of a cooperation with government
agencies, competing manufacturers and a "consortium of
banks," but would not provide further details. HP said
in a statement that it is involved in
anti-counterfeiting measures and supports the
cooperation between the printer industry and those who
are working to reduce counterfeiting.

Schoen said that the existence of the encoded
information could be a threat to people who live in
repressive governments or those who have a legitimate
need for privacy. It reminds him, he said, of a
program the Soviet Union once had in place to record
sample typewriter printouts in hopes of tracking the
origins of underground, self-published literature.

"It's disturbing that something on this scale, with so
many privacy implications, happened with such a tiny
amount of publicity," Schoen said.

And it's not as if the information is encrypted in a
highly secure fashion, Schoen said. The EFF spent
months collecting samples from printers around the
world and then handed them off to an intern, who came
back with the results in about a week.

"We were able to break this code very rapidly," Schoen
said.