Today I learned that many/most color laser printers layer an array of yellow microdots on top of documents 🔬
This Machine Identification Code https://en.wikipedia.org/wiki/Machine_Identification_Code encodes a print date and a serial number unique to the machine. It only became public knowledge in 2004, ~20 year after deployment 😑
The Technical University of Dresden released a tool 2 years ago to layer on _even more dots_ to render the MIC unreadable and aid whistleblowers publishing https://github.com/dfd-tud/deda ✊
@douginamug That is how whistleblower Reality Winner was identified and arrested.
@joachim damn. And to think I had no idea I was producing these dots myself til last week!
@jums @douginamug @joachim
There's a US FOIA answer with a list of manufacturers that include these, and it's ...basically all of them ;) since we're on this topic, if you want to add dots to your document for fun, use these: https://en.wikipedia.org/wiki/EURion_constellation :P
@krugar @joachim @douginamug @jums there's a lot of fuzziness there. For some printers there is a concrete "yes" to the #trackerdots question, and for others it's up in the air. Obviously ppl should avoid buying a printer that's confirmed compromised. Oki is a good bet. It's non-US, & Oki doesn't have scandals and dirt that most makers have.
@jums @douginamug @joachim @krugar This is where some of my info comes from: https://www.eff.org/pages/list-printers-which-do-or-do-not-display-tracking-dots
@joachim @douginamug It's interesting that the dots were readable on The Intercept's *published version* of the documents, which seems to imply they did a really high quality color scan, no? Who does that? Why wouldn't a newspaper be smart enough to scan (presumably text) docs as a bitonal image where a yellow dot would be assigned white and not black?
@douginamug I know this case from EFF explanation several years ago. Thanks for sharing this important thing.
@douginamug so, this is really cool but it isn't universally applied to ALL prints from a colour laser.
What I've found is that colour laser printers at work won't print these for black and white docs - i suspect this is common since these dots are usually printed in yellow and you don't wanna spin up the colour laser elements if it isn't a colour print job. (it takes ~20 seconds longer to get ready to print colour than it does b+w)
@c24h29clo4 Interesting! Will have to check that out. Housemate managed to identify them on a print, but not sure if he used color...
@douginamug keep in mind, these are corporate machines on a printers-as-a-service contract. No guarantee the feature isn't disabled to save toner or otherwise comply with business or legal privacy rules. I have definitely seen the dots around, just much less frequently on like, bulk letters and similar
Wow this stuff goes deeper
Now I wonder if my printer would let me copy a note - I won't try it though since it is internet connected...
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