On Sat, 17 Aug 2019 17:24:44 +0000 (UTC), danny burstein
wrote:

In Jeff Liebermann writes:

[snip]

Machine Identification Code
https://en.wikipedia.org/wiki/Machine_Identification_Code

I recently inherited from a customer an HP LaserJet Pro m477fnw color
laser printer:
https://www.amazon.com/HP-Color-LaserJet-M477fnw-Renewed/dp/B01N5XP9TL/
Quite good, but this particular model doesn't do double sided
printing. When I picked up the printer, the yellow toner level was
well below the other colors. The dots are visible with a microscope
and UV illumination.

Grumble...

Periodically, the great folk (overworked, understaffed...)
at the EFF do things like:

https://www.eff.org/pages/list-print...-tracking-dots

More from the EFF:
https://www.eff.org/issues/printers
The encoding seems to be different for different manufacturers. After
about 14 years, only the Xerox codes seem to have been fully decoded:
https://www.techdirt.com/articles/20180626/09114540109/researchers-reveal-details-printer-tracking-dots-develop-free-software-to-defeat-it.shtml
https://www.researchgate.net/publication/325976319_Reverse_Engineering_the_Machine_Identifi cation_Code
https://dfd.inf.tu-dresden.de
https://blog.erratasec.com/2017/06/how-intercept-outed-reality-winner.html#.XVhP3kd7laS


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558