(in other words, be more careful with your titles relating to papers that are REALLY out of date)
The wikipedia article on laser printers links to a nice sample on a 1cm ruler... http://en.wikipedia.org/wiki/File:Printer_Stenography_Illust...
The part of this that I find most interesting is that these have been known since the 90s and in 2005 there was a flurry of interest as some of the schemes were decoded, but I have never seen an authoritative reason why they are there. Does some entity in the US government require them? By what legal mechanism? Are the printer manufacturers trying to avoid liability for manufacturing counterfeiting equipment?
I can think of a couple of scenarios:
1) During the driver installation process, the serial number and the user info stored on the system is (edit: could be) sent to the manufacturer. This might be defeated by using an open OS and drivers. The user could also use the printer with a system that is never connected to the Net.
2) The Secret Service would be able to track the printer down to the store where it was purchased. The retailer would be able to supply credit/debit receipts, but what if the buyer pays for the printer with cash? The Secret Service would have to rely on the store's video surveillance system (who knows how long they keep these records?) or on eyewitness descriptions from the store clerks and cashiers (which may not be too reliable).
And unless the printer is only used for disfavored purposes, its other output is in circulation. Who's to say there's not a ad hoc registry maintained by paper samples culled from filed forms or even trash dumps and recycling bins. ("That serial number was never registered but it was sold from a retail store in Cleveland in 2002 and its printouts were seen in recycling flows in Maryland in 2006.")
It think it's for confirming that a particular printer made a particular note (and determining how many different printers are involved in counterfeiting). Nothing more.
I submitted this article because I genuinely thought it was interesting and wanted to share it with like minded tech savvy people. (My real life friends wouldn't really care about this :-p)
I chose to submit this page rather than the newer version ( http://eff.org/issues/printers ) because I found the image of the dots on this webpage very interesting. I figured if people were interested they could click the "For up-to-date" information link. I will save everyone a click next time.
If not: print out one copy and photocopy from it as many as you need before destroying the original.
Class action lawsuit anyone?
Unlike, um, some people.