> Where do you see the bit about visual derivatives? In Apple's white paper about the proposed feature: https://www.apple.com/child-safety/pdf/CSAM_Detection_

> Where do you see the bit about visual derivatives? In Apple's white paper about the proposed feature: https://www.apple.com/child-safety/pdf/CSAM_Detection_Technical_Summary.pdf https://www.apple.com/child-safety/pdf/CSAM_Detection_Techni... See the links at the bottom here for more: https://www.apple.com/child-safety/ https://www.apple.com/child-safety/ > Also what is this threshold? The "perceptual hash" is supposed to match a specific image (though possibly cropped, or otherwise altered a bit, such as through a filter), not "toddlers" per se. > Google doesn't use perceptual hashing, or at least haven't said they do. I don't know what the other cloud providers are doing, but I'd be very surprised if they use (trivially circumventable) cryptographic hashes.