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EFF's “Yellow Dots of Mystery” (2008) (eff.org)
107 points by chdir on March 26, 2015 | hide | past | favorite | 30 comments



Hi folks, I wrote a lot of this and appear in the video.

I thought at the time that the most significant part of this is that private companies would agree to participate in secret government programs to modify the design of their technology, even without being legally compelled to, and then most of them would not talk about it. That's a bigger deal than what the particular technology actually does.

I still think that was exactly right.

The second-biggest part for me is that a lot of people don't see a core value in anonymous publishing, so we see some technologies with intentional forensic marking of documents -- especially this and optical media, which the recording industry and U.S. government have pushed to have marked with indications of where discs were manufactured. Those technologies are a major threat to underground and samizdat media because a government has an unambiguous starting point to figure out what device or facility produced the documents. Document forensics exists, and it will always be possible to learn something about the provenance of a document by physical examination, but actually putting device serial numbers into the documents -- especially without clearly warning the users -- is way uncool if you think there should be able to be anonymous mass media.


Without weighing in on the merits, it's not uncommon for companies to preemptively adopt self-regulation in an effort to keep legally compelled regulation at bay.


NSA advocate: But it's OK, only the NSA can decode the data and they only use the data for legitimate nation security.

Some nerd: The code has been cracked and anybody can download a program to decode them, giving access to private and possible sensitive data to anybody who wants it.

NSA Advocate: Hmm, next time will make the code harder to crack or something other than stopping to coercing businesses from building in far-from-impenetrable back doors into public consumer products that are used by hundreds of millions.


some related and useful info:

https://www.eff.org/pages/list-printers-which-do-or-do-not-d...

i wonder if mono black laserjets have similar issues.


From the linked 'seeing yellow' site:

"They are present in both color printers and copiers but do not show up in pages printed in black-and-white mode."


Because you can't print counterfeit currency with black and white, which is ostensibly the reason the whole thing got started.


Couldn't you replace the black ink with green ink and then print in "Black and White" mode?


My guess is that you wouldn't get the shades right. Maybe with a lot of trial-and-error, but at some point it's easier to just make some printing plates and go that route. Either way the paper is the real problem.


So you could substitute green ink in the black ink container?


Time to start a Paper company with pre-printed random yellow dots in it... The pre-printed dots should confuse the hell out of the Printer-printed dots....


In terms of anonymity though, there'd have to be a lot of people buying your paper to avoid uniqueness any individual document. Maybe you could buy, rebrand and resell the most commonly sold yellow paper as 'Super Secret Document Paper'!


Or you could print some garbage in the margins using several different printers, ending up with a pattern that can't be read unambiguously.


You'd need a lot of yellow dots to lower the SNR.


I wonder if it is this sort of thing, along with patents in the industry, that prevents open source printers from taking off.


There is nothing that prevents one from making opensource laser printer. Except the fact that the whole mechanism is decidedly non-trivial to get right. You get precision mechanics, high voltage, large resistive heating element and multimegabit serial datastreams that have to be phase locked to mechanical movement in one little box that can be bought off the shelf for <100USD. For that matter many "printer manufacturers" actually buy the whole print engine as a module from somebody else as there is not much to be gained by designing and manufacturing it in-house.


When Color laserjet copiers first started being manufactured to the present quality that they are now I understand that the Treasury Dept requested manufacturers to include serial numbers in printed copy to track forgers of currencies. Microscopic serial numbers can be found within images interspersed throughout the image.


The 21C3 lecture from Stephen Murdochs on reverse engineering photoshop and printers attempting to detect currency also of interest.

http://www.cl.cam.ac.uk/~sjm217/projects/currency/

http://events.ccc.de/congress/2004/fahrplan/event/108.en.htm...


Use FedEx Kinko's. Wear a baseball cap and sunglasses when you go in.


with your phone left behind you and having dodged any security cameras between there and where you live.

...and all you want to do is print some flyers for a bake sale.


If the secret police want to know where your bake sale is, they'll probably just read the address on the flyer instead of decoding the magic tracking dots.


"...print some flyers for a bake sale."

Hey, defeating traffic analysis isn't complex, it just takes a lot of work.


I wonder if something like that is implemented in 3D printers.


If we're talking about FDM...

Unless you're buying from a non-open-hardware company (like Makerbot, which you shouldn't anyway), you should be fine. Thhey use an all open-source software chain (ie. Slic3r -> Printrun/OctoPrint -> Marlin)


... to stop someone forging gold bars?


Presumably such a mechanism in 3D printers would be used to try to stop people from printing guns and anything else a government might frown upon, like drug paraphernalia, etc.


Or from making offset printing plates that can be used to print dollars.



NOT related. This is not meant to track you. This is just a marking.


It's a subliminal marking that is also a software instruction honored by most, if not all color copiers and scanners and many graphics software applications.


so can someone post a link to a tool or tools where one can decode these dots?




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