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They are perceptual hashes of CSAM images no? Sure, just because they are perceptual hashes, doesn't mean they can be reversed to an image, but it seems to be t
by nabakin 5y ago
They are perceptual hashes of CSAM images no? Sure, just because they are perceptual hashes, doesn't mean they can be reversed to an image, but it seems to be true PhotoDNA, a similar perceptual hashing algorithm, can be reversed to an image. For this reason, I believe it is possible Apple's perceptual hashes can be reversed as well, though, maybe they did it in a different way and it's not possible
- robertoandred 5y agoPhotoDNA is Microsoft’s algorithm. Apple’s new one is NeuralHash. Plus the hashes are encrypted and blinded before being stored on the phone. They can’t be reversed.
- nabakin 5y agoIn order for this system to work, Apple has to be able to compare the CSAM NeuralHash hashes against the NeuralHash hashes of the images to be synced with iCloud. How do they compare the hashes without decrypting?
- robertoandred 5y agoThey compare the encrypted forms of the hashes, the first step on the device and the second on the server.
- postalrat 5y agoHow does one compare encrypted forms of hashes?
- robertoandred 5y agoYou hash images in the same way, then encrypt the hashes in the same way, and see if the results match.
- postalrat 5y agoThen you are just comparing hashes. I don't see what you gained by encrypted the hash.