31–40 of 72 posts
Earlier quoted context omitted.
https://github.com/freedomofpress/dangerzone/blob/main/dange... How hard did you look the other times?
Not much further than their documentation, friend! But thanks for finding that, that's actually super helpful! I hope somebody puts in a pr for updating the documentation to make it clear what functionality their tool has.
I personally just upload them to google drive. It would be a serious pwn if they could somehow still do a compromise through google drive.
Does google drive apply any transformation over the PDF, or are you effectively loading the same document in your browser on the round trip?
Earlier quoted context omitted.
I assume they mean "upload to drive and use the web based reader to view the PDF," not "upload to drive and download it again"
And what special sauce does the web preview use? At some point, someone has to actually parse and process the data. I feel like on a tech site like Hacker News, speculating that Google has somehow done a perfect job of preventing malicious PDFs beckons the question: how do you actually do that and prove that it's safe? And is that even possible in perpetuity?
Earlier quoted context omitted.
Not much further than their documentation, friend! But thanks for finding that, that's actually super helpful! I hope somebody puts in a pr for updating the documentation to make it clear what functionality their tool has.
I can show you the link for how to do that too if needed.
I personally just upload them to google drive. It would be a serious pwn if they could somehow still do a compromise through google drive.
Earlier quoted context omitted.
I seem to remember Yahoo finance (I think it was them, maybe someone else) introducing benign errors into their market data feeds, to prevent scraping. This lead to people doing 3 requests instead of just 1, to correct the errors, which was very expensive for them, so they turned it off. I don't think watermarking is a winning game for the watermarker, with enough copies any errors can be cancelled.
> I don't think watermarking is a winning game for the watermarker, with enough copies any errors can be cancelled. This is a very common assumption that turns out to be false. There are Tardos probabilistic codes (see the paper I linked) which have the watermark scale as the square of the traitor count. For example, with a watermark of just 400 bits, 4 traitors (who try their best to corrupt the watermark) will stan…
I'm not totally convinced that the threat model is realistic. The watermarker has to embed the watermark, the only place to do that is in the least significant bits of whatever the message is. If it's an audio file then the least significant bits of each sample would work. If it's a video file then the LSBs in a DCT bin may also be unnoticeable. It can really only go in certain places, without it affecting the content in a meaningful way. If it's in a header, or separate known location, then the pirate can just delete those bits.
The threat model presented says the pirates have to go with one of the copies, or only correct errors that are different between 2 copies. That's the part that I don't think is realistic. If the pirates knew that the file was marked, and the scheme used to mark it, but didn't know the key (a standard threat model for things like encryption), then they could inject their own noise into wherever the watermark could be hiding, and now the problem is the watermarker trying to send a message on a noisy channel, where the pirates have a jammer. I don't even think you have to sacrifice quality, since the copy you have already has noise, and you just need to inject the same amount (or more).
Earlier quoted context omitted.
I assume they mean "upload to drive and use the web based reader to view the PDF," not "upload to drive and download it again"
And what special sauce does the web preview use? At some point, someone has to actually parse and process the data. I feel like on a tech site like Hacker News, speculating that Google has somehow done a perfect job of preventing malicious PDFs beckons the question: how do you actually do that and prove that it's safe? And is that even possible in perpetuity?
While useful it needs a big red warning to potential leakers. If they were personally served documents (such as via email, while logged in, etc) there really isn't much that can be done to ascertain the safety of leaking it. It's not even safe if there are two or more leakers and they "compare notes" to try and "clean" something for release. https://en.wikipedia.org/wiki/Traitor_tracing#Watermarking https://arxiv.org…
Why not just open it inside of and print to a static image output within a fully sandboxed Docker container?