Tracking printed docs: EFF examines codes printed on docs

["Jon O." <jono () networkcommand com>]

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

On Nov. 22, 2004, PC World published an article stating that "several printer companies quietly encode the serial 
number and the manufacturing code of their color laser printers and color copiers on every document those machines 
produce. Governments, including the United States, already use the hidden markings to track counterfeiters." According 
to the article, the high fidelity of outputs from color machines to their original documents suggests that 
counterfeiters can potentially succeed in creating high-quality counterfeited currency and government documents using 
these machines. At the request of the United States Secret Service, manufacturers developed mechanisms that print in an 
encoded form the serial number and the manufacturer's name as indiscernible markings on color documents. The Secret 
Service and manufacturers would be able to decode these values from the markings and in the event a color machine was 
used to print a suspected counterfeited document, these values would be used with customer information to discover the 
identity of the machine's owner.

[see link above for more info]