EFF research into hidden codes colour prints

The US based digital rights organisation EFF has started extensive
research into the hidden codes some laser colour printers and photo
copiers add to every page they print or copy. In 2004 printer-manufacturer
Canon was awarded a Big Brother Award in Germany for secretly adding a
unique code to every print-out. Soon after, it turned out the practice is
very wide-spread.

The unique number on every print-out is invisible to the bare eye,
measuring only 0,1 millimetre. After the Big Brother Award for Canon, the
Dutch police immediately admitted they use the codes to detect the sources
of print-outs, tracing individual printers through the vendor chain.
Questioned by the Lower House, the Dutch minister of Economical Affairs
said he agreed manufacturers should inform their customers, but did not
create any obligation in that direction.

EFF suspects the US government of having persuaded most manufacturers of
including the secret codes, “in a purported effort to identify
counterfeiters.” In addition to a call to the public to send in
print-outs, to create an even more extensive list of printers, EFF has
filed a Freedom of Information Act (FOIA) request to find out all about
“the Secret Service’s efforts to promote the development and
implementation of machine identification code (MIC) technology in colour
laser printers and colour photocopiers.”

EFF: Is Your Printer Spying On You? (13.10.2005)
http://www.eff.org/Privacy/printers/

EDRI-gram ‘Secret code added to most colour prints’ (03.11.2004)
http://www.edri.org/edrigram/number2.21/printers