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submitted 4 months ago by fossilesque@mander.xyz to c/science_memes@mander.xyz

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[-] sandbox@lemmy.world 18 points 4 months ago

it’s possible using steganographic techniques to embed digital watermarks which would not be stripped by simply printing to pdf.

[-] FinalRemix@lemmy.world 22 points 4 months ago

Got it. Print to a low quality JPG, the use AI upscaling to restore the text and graphs.

[-] Syn_Attck@lemmy.today 13 points 4 months ago

You should spread that idea around more, it's pretty ingenious. I'd add first converting to B&W if possible.

[-] Syn_Attck@lemmy.today 12 points 4 months ago* (last edited 4 months ago)

This is a great point. Image watermarking steganography is nearly impossible to defeat unless you can obtain multiple copies of the 'same' file from multiple users to look for differences. It could be a change of a single 5-15 pixels from one rgb code off.

rgb(255, 251, 0)

rgb(255, 252, 0)

Which would be imperceptable to the human eye. Depending on the number of users it may need to change more or less pixels.

There is a ton of work in this field and its very interesting, for anyone considering majoring in computer science / information security.

Another 'neat' technology everyone should know about is machine identification codes, or, the tiny ~~secret~~ tracking dots that color printers print on every page to identify the specific make, model, and serial number (I think?) of the printer the page was printed from. I don't believe B&W printers have tracking dots, which were originally used to track creators of counterfeit currency. EFF has a page of color printers which do not include tracking dots on printed pages. This includes color LaserJets along with InkJets, although I would not be surprised if there was a similar tracking feature in place now or in the future "for safety and privacy reasons," but none that I am aware of.

[-] sus@programming.dev 3 points 4 months ago* (last edited 4 months ago)

I wonder if it's common for those steganography techniques to have some mechanism for defeating the fairly simple strategy of getting 2 copies of the file from different sources, and looking at the differences between them to expose all the watermarks.

(I'd think you would need sections of watermark that are the same for any 2 or n combinations of copies of the data, which may be pretty easy to do in many cases, though the difference makes detecting the general watermarking strategy massively easier for the un-watermarkers)

[-] Thann@lemmy.ml 2 points 4 months ago

When is why you steghide random data to the image to fuck up the other end =]

[-] Syn_Attck@lemmy.today 2 points 4 months ago

Unless you know specifically what they're adding or changing this wouldn't work. If they have a hidden 'barcode' and you add another hidden 'barcode' or modify the image in a way to remove some or all of theirs, they'd still be able to read theirs.