3 ms·
No, there’s another private hash function that also has to match the known CSAM image for an image to be considered a match. That one can’t be figured out thro
by ec109685 5y ago
No, there’s another private hash function that also has to match the known CSAM image for an image to be considered a match.
That one can’t be figured out through this technique.
- Syonyk 5y agoThey couldn't possibly be using the "other perceptual hash algorithm commonly used for this stuff," PhotoDNA, could they? I mean, hopefully not, but at this point, it's reasonable to call just about everything into question on the topic.
- ec109685 5y agoTheir goal is to minimize false positives, so would not be in their best interest.
- vermilingua 5y agoBut surely if they're doing this in anticipation of E2EE user data, that procedure becomes moot? So either they have no intention to actually protect user data, or the system is trivially broken; either way a pretty damning look for Apple.
- comex 5y agoNo, because the second hash is only performed after the first hash has already matched, and so, using the threshold secret sharing crypto, the server has learned the escrowed encryption key for the image. (Well, for its “visual derivative”, at any rate.)
- vermilingua 5y agoSo, Apple retains the ability to decrypt E2EE data? That’s… worse?
- ec109685 5y agoOnly E2EE data that matches known CSAM hashes, and only when 30 matches have been found, and only the “visual derivative” of those images.
- M4v3R 5y agoWhich means all it takes now is one disillusioned Apple employee to leak the details of thay private hash function and the whole system is compromised.
- jdlshore 5y agoOne disillusioned employee that has access to the secret algorithm.