Shit, heavy topic for first time back.
Well, the Electronic Frontier Foundation has done some great work compiling data on how many business sized laser printers add almost invisible yellow dots to every printed page. Those yellow dots are a coded way of stamping the paper with the make, model, and serial number of the printer; and the time, date, and file name of the print job. Also, that data is put there at the request of the Secret Service. FOIA is a great fucking program that oughta be strengthened: https://www.eff.org/foia/foia-printer-dots
None of the printers I use are on the list of printers put together by the EFF. So it was time to check test pages myself — especially the printer I know is used to make agendas for Occupy Berkshires meetings. Can the Secret Service track papers printed for political rallies I attend? Fuck yeah!
Here are the yellow dots, raw but magnified:
Here is a much larger section, altered in GIMP to boost contrast. Also a rectangle is added so you can more clearly see that this is a repeated pattern, not just random dots:
So if you have access to a laser printer you should really help the EFF figure out the encoded messages by printing test pages and sending them in.
I’ve gotten into the ideas of software freedom, and have been struggling to find where exactly I stand. I think this, for me, crystallizes why people fight for free software. Printers wouldn’t print tracking data for too long if they came with source code. Say — where can I get some libre firmware for a Konica printer? Preferably ones that print invisible smiley faces that mean nothing :)