Tuesday, June 06, 2017

What about other leaked printed documents?

So nat-sec pundit/expert Marci Wheeler (@emptywheel) asks about those DIOG docs leaked last year. They were leaked in printed form, then scanned in an published by The Intercept. Did they have these nasty yellow dots that track the source? If not, why not?

The answer is that the scanned images of the DIOG doc don't have dots. I don't know why. One reason might be that the scanner didn't pick them up, as it's much lower quality than the scanner for the Russian hacking docs. Another reason is that the printer used my not have printed them -- while most printers do print such dots, some printers don't. A third possibility is that somebody used a tool to strip the dots from scanned images. I don't think such a tool exists, but it wouldn't be hard to write.

Scanner quality

The printed docs are here. They are full of whitespace where it should be easy to see these dots, but they appear not to be there. If we reverse the image, we see something like the following from the first page of the DIOG doc:


Compare this to the first page of the Russian hacking doc which shows the blue dots:


What we see in the difference is that the scan of the Russian doc is much better. We see that in the background, which is much noisier, able to pick small things like the blue dots. In contrast, the DIOG scan is worse. We don't see much detail in the background.

Looking closer, we can see the lack of detail. We also see banding, which indicates other defects of the scanner.

Thus, one theory is that the scanner just didn't pick up the dots from the page.

Not all printers

The EFF has a page where they document which printers produce these dots. Samsung and Okidata don't, virtually all the other printers do.

The person who printed these might've gotten lucky. Or, they may have carefully chosen a printer that does not produce these dots.

The reason Reality Winner exfiltrated these documents by printing them is that the NSA had probably clamped down on USB thumb drives for secure facilities. Walking through the metal detector with a chip hidden in a Rubic's Cube (as shown in the Snowden movie) will not work anymore.


But, presumably, the FBI is not so strict, and a person would be able to exfiltrate the digital docs from FBI facilities, and print elsewhere.


Conclusion

By pure chance, those DIOG docs should've had visible tracking dots. Either the person leaking the docs knew about this and avoided it, or they got lucky.





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