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German Researchers Defeat Printer-Tracking Yellow Dots

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

-- OriginalOwner_ writes:

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

Original Submission

 
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  • (Score: 1, Interesting) by Anonymous Coward on Thursday June 28 2018, @08:39PM (5 children)

    by Anonymous Coward on Thursday June 28 2018, @08:39PM (#699967)

    Substitute black toner cartridge for yellow toner cartridge, printer no-workie.

    You can get third party refillable ink cartridges for many popular printers:

    https://lightzonephoto.wordpress.com/2015/02/20/my-epson-r2400-conversion-to-third-party-inks/ [wordpress.com]

    https://refreshcartridges.co.uk/ [refreshcartridges.co.uk]

    I think it's possible to fill the yellow toner with something that readily evaporates.

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  • (Score: 1, Informative) by Anonymous Coward on Thursday June 28 2018, @09:05PM (4 children)

    by Anonymous Coward on Thursday June 28 2018, @09:05PM (#699978)

    The toner cartridge doesn't need to contain anything for the printer logic to detect it as full.

    Do you realize that the "toner empty" flag doesn't actually check, weight or sense in any way the physical presence of toner at all?

    These checks are just some sort of usage counter, smartchip, gears, or even embedded software all of which can be reset in a way or another without any real toner involved.

    You always could buy a brand new toner cartridge, dump all the toner and clean the shell and then use it as it were full without actually printing anything ever with it.

    • (Score: 2) by frojack on Thursday June 28 2018, @09:12PM (3 children)

      by frojack (1554) on Thursday June 28 2018, @09:12PM (#699984) Journal

      BS. Toner is electrically sensed, (it conducts electricity) not only in the cartridge but on the drum.

      --
      No, you are mistaken. I've always had this sig.

      • (Score: 0) by Anonymous Coward on Thursday June 28 2018, @11:33PM (2 children)

        by Anonymous Coward on Thursday June 28 2018, @11:33PM (#700023)

        BS. Toner is electrically sensed, (it conducts electricity) not only in the cartridge but on the drum.

        I don't know in what world you live in but in the real world toner is an insulator (it doesn't conduct electricity) to be able to hold any electrostatic charge and adhere to the photosensitive imaging drum.

        That's virtually any existing laser printer technology based on electrostatic processes.

        You can check it yourself printing a 100% fill area with the densest settings in any color you like, get a MOhm tester and verify that the resistence is out of range.

        • (Score: 2) by Deeo Kain on Friday June 29 2018, @11:22AM (1 child)

          by Deeo Kain (5848) on Friday June 29 2018, @11:22AM (#700205)

          http://smallbusiness.chron.com/printer-low-toner-61441.html [chron.com]

          Other printer models and manufacturers provide a more accurate measurement by installing sensors in their toner cartridges. These sensors are covered with toner when the cartridge is full, then become exposed over time as you print pages and the toner level declines. When the cartridge reaches a level set by the manufacturer, your low-toner indicator will light.

          • (Score: 0) by Anonymous Coward on Friday June 29 2018, @04:23PM

            by Anonymous Coward on Friday June 29 2018, @04:23PM (#700271)

            Linked article author: Fred Decker

            Fred Decker is a trained chef and certified food-safety trainer. Decker wrote for the Saint John, New Brunswick Telegraph-Journal, and has been published in Canada's Hospitality and Foodservice magazine. He's held positions selling computers, insurance and mutual funds, and was educated at Memorial University of Newfoundland and the Northern Alberta Institute of Technology.