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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 deimtee on Friday June 29 2018, @09:12AM

    by deimtee (3272) on Friday June 29 2018, @09:12AM (#700173) Journal

    The thing is, it is a very regular pattern of precisely sized dots that repeats multiple times. While you might obscure a random point on a grid, extracting a repeating signal buried in background noise is pretty much a solved problem.

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