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posted by martyb on Thursday June 28 2018, @07:28PM   Printer-friendly
from the measures-and-countermeasures dept.

The Register reports

Beating the unique identifiers that printers can add to documents for security purposes is possible: you just need to add extra dots beyond those that security tools already add. The trick is knowing where to add them.

[...] researchers from the Technical University of Dresden [...] Timo Richter, Stephan Escher, Dagmar Schönfeld, and Thorsten Strufe reckon they've cracked the challenge of knowing how to anonymise printed documents, and presented their work to the Association of Computer Machinery's 6th ACM Workshop on Information Hiding and Multimedia Security in Innsbruck, Austria [the week of June 22].

In this paper, the TU Dresden researchers explain that they tested 1,286 documents printed on machines from 18 manufacturers, creating an extraction algorithm to identify well-known dot-patterns--and at the same time, discovering four previously undiscovered patterns coding at 48, 64, 69, and 98 bits.

Identifying new patterns is important, from a privacy point of view, since as the authors points out, an activist in a dictatorship could easily be unmasked by their printer (unless they happen to use a Brother, Samsung, or Tektronix printer, none of which seemed to carry tracking codes, the researchers said).

[...] The group has published [a] toolkit that automates the obfuscation workflow, here.

Previous: "Printer Dot Sanitisation" Software Seeks to Cleanse Yellow-Dot Watermarks


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  • (Score: 2) by tfried on Friday June 29 2018, @10:02AM (2 children)

    by tfried (5534) on Friday June 29 2018, @10:02AM (#700186)

    Laser isn't that hard of a thing to build

    Probably, a lot of very wonderful projects would never have been started, if their creators had not underestimated the required efforts by orders of magnitude. So, I'm not here to stop you. But just for reference: Have you ever seen one of those early photocopiers or laser printers? Try an image search for lbp-10 for instance (and that's not even the first laser printer, by far, only the first "desktop" model). The working principle has not really changed since then. Sure, the electronics will be a lot easier, today, and we have 3D-printing to help with the hardware. But I'll still be rather impressed, if you manage to craft as much as a reliable paper feed from the ground up.

    Or, of course, you could use existing parts. But in that case, the easiest option would seem to be to buy a complete laser printer, and "simply" solder your own wires to the laser diode. You'll still have to solve the synchronisation, and possibly hack around self-tests, and such, but at least that sounds like something that could be solved with reasonable effort.

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  • (Score: 0) by Anonymous Coward on Friday June 29 2018, @05:39PM

    by Anonymous Coward on Friday June 29 2018, @05:39PM (#700293)

    And ultimately you'll get the National Security Letter telling you you're getting a free update to your hardware NOW. Please leave the room NOW with these nice gentlemen.

  • (Score: 2) by DannyB on Monday July 02 2018, @04:12PM

    by DannyB (5839) Subscriber Badge on Monday July 02 2018, @04:12PM (#701432) Journal

    Don't laser printers involve high voltages to charge the drum?

    --
    People today are educated enough to repeat what they are taught but not to question what they are taught.