Many but not all colour laser printers embed tracking data within the
printout allowing suitably knowledgeable people to decode things such
as printer ID, date, time and possibly other information useful to
identify the user. This feature was added by printer makers by
agreement with US authorities to allow counterfeiters to be
identified, but obviously has wider implications and applications.

The EFF has recently broken the coding for the Xerox Docucolor
printers and is working on others.
Second story on page

        http://www.eff.org/news/archives/2005_10.php#004063

Printers with this 'feature'

        http://www.eff.org/Privacy/printers/list.php

How to see the dots & how to decode Xerox doculcolor codes

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

Analysing other printer versions

        http://www.eff.org/Privacy/printers/wp.php#testsheets


        RM


______________

Ref Matthew McMahon 

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