3 ms·

https://en.wikipedia.org/wiki/PhotoDNA https://en.wikipedia.org/wiki/PhotoDNA They usually aren't using SHA (maybe they are in this specific case).

• kakarot 9y ago
  Oh cool, I'd heard of PhotoDNA but I didn't know the details behind it. Thanks! "It works by converting the image to black and white, re-sizing it, breaking it into a grid, and looking at intensity gradients or edges." Pretty cool piece of technology. Seems like it covers the obvious bases. I imagine it also ignores meta tags as part of the hashing process, and operates directly on the pixel information. Perhaps one way to circumvent detection without making perceptual modifications (which would have to be somewhat significant to thwart the above method) could be a program that losslessly converts all of your images' pixel data to a generated file type only understandable by a program with a specific key in memory, which either directly displays the image or creates temporary files that could be used by a regular image viewer? The files could possibly be signed by more than one party for extra protection. I know it sounds just like encryption but I'm thinking of something a little different. Sort of a singular encrypted file that can be securely transferred to any file system. Sounds like a fun and challenging project but I'd hate for it to be so successful that it leads to child pornographers getting off the hook. "In December 2016, Facebook, Twitter, Google and Microsoft announced plans to use PhotoDNA to tackle extremist content such as terrorist recruitment videos or violent terrorist imagery." Dear lord, that is a stupendously slippery slope.