Text 7751, 65 rader
Skriven 2005-10-19 19:49:48 av Rich Gauszka (1:379/45)
Ärende: Tracking your color laser printouts
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From: "Rich Gauszka" <gauszka@hotmail.com>

I reckon Bin Laden will now switch to dot matrix <g>

http://www.tgdaily.com/2005/10/19/eff-decodes-printertrackingdots/


The next time you use the office printer, you may be printing up a lot more
than sales figures or quarterly reports. Many color laser printers are secretly
embedding tracking dots, minute and almost invisible yellow specks, on
documents. While many have speculated on the meaning of the dots, the
Electronic Frontier Foundation (EFF) appears to have decrypted the code.

For the better part of the last year, computer experts have known about the
existence of printer tracking technology. Last November, PC World published the
article, Government Uses Color Laser Printer Technology to Track Documents,
which discussed the existence of printer tracking dots. Seth Schoen, staff
technologist at the EFF, told us that the PC World article spurred EFF to
investigate further. Initially Schoen, like PC World, speculated that the dots
would only contain the printer's serial and model number, but now it is
confirmed that there is much more information included. "As it turned out,
there is also the date and time, which is accurate to the minute. We didn't
expect that," says Shoen.

Schoen says that these tracking dots are "all over" every page printed from
many printer models. The dots are almost invisible, but can be seen by shining
a simple blue LED light on the page. The blue light increases the contrast of
the yellow dots and causes them to appear black against the paper background.
In the case of one particular printer, the Xerox DocuColor, the dots appear as
an eight by fifteen grid that is repeated throughout the page.

Schoen told us that he and four other people decoded the dots. Two volunteers,
Patrick Murphy and Joel Alwen, and summer intern Robert Lee did much of the
work. Andrew Huang, author of "Hacking the Xbox" helped out by modifying a
scanner to shine extra blue light on the printouts. To gather enough data, EFF
asked volunteers from around the world to send in printouts from as many
printers as possible. "We got several hundred sets from about 100 different
models and the documents are still arriving," says Schoen.


So far, EFF has only decoded the tracking dots on the Xerox DocuColor line of
printers/copiers. The DocuColor is an expensive high-volume printer used in
many major print shops such as Kinko's, but Schoen warns that the tracking dots
are also produced on more down to Earth printers. "The tracking dots appear in
all models from low end to high end. We've seen them on some Dell printers
costing as little as $299," says Schoen.

Schoen encourages everyone to try this out saying, "People don't have to take
our word for it. Go down to Kinko's yourself. They will see that the tracking
dots are all over the page and probably has been done for at least a decade."

http://www.eff.org/Privacy/printers/docucolor/index.php

This guide is part of the Machine Identification Code Technology project. It
explains how to read the date, time, and printer serial number from forensic
tracking codes in a Xerox DocuColor color laser printout. This information is
the result of research by Robert Lee, Seth Schoen, Patrick Murphy, Joel Alwen,
and Andrew "bunnie" Huang. We acknowledge the assistance of EFF supporters who
have contributed sample printouts to give us material to study. We are still
looking for help in this research; we are asking the public to submit test
sheets or join the printers mailing list to participate in our reverse
engineering efforts.

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