In this thread there are a lot of valid concerns about client-side fingerprinting and how this would allow sophisticated algorithms to be broken. Putting someth

In this thread there are a lot of valid concerns about client-side fingerprinting and how this would allow sophisticated algorithms to be broken. Putting something like PhotoDNA on clients is probably not good. However, I think a simpler approach would handle >95% of cases here, and that’s to just calculate the image sha and use that. It does nothing for resizes/obfuscations, but if Facebook users are dumb enough to volunteer their nudes to human review, they’re dumb enough to not modify images before reposting them as revenge porn. Everything else with respect to modified images and elaborate fingerprinting and perceptual hashing can happen at the next tier, which I trust Facebook already has an intricate (and publicly tolerated) system to handle.