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Have they? The whitepaper made it sound like the encrypted security voucher is created from the database of known cp on the device at the time the image is uplo
by davidcbc 5y ago
Have they? The whitepaper made it sound like the encrypted security voucher is created from the database of known cp on the device at the time the image is uploaded, and the only way for Apple to decrypt something is if it matched something in that database.
It did not sound like they could retroactively add additional hashes and decrypt something that already was uploaded. They could theoretically add something to the list of hashes and catch future uploads of it but my understanding was they cannot do this for stuff that has already been stored.
- sathackr 5y agoDirectly from the link: > ...the system performs on-device matching using a database of known CSAM image hashes provided by NCMEC and other child safety organizations. Apple further transforms this database into an unreadable set of hashes that is securely stored on users’ devices. >... The device creates a cryptographic safety voucher that encodes the match result along with additional encrypted data about the image. This voucher is uploaded to iCloud Photos along with the image.
- vineyardmike 5y ago> they cannot do this for stuff that has already been stored. That's a very simple software update. Every year iOS gets more images the automatic tagging supports (dogs, shoes, bridges, etc). And if you add a friend's face to known faces, it'll go and search every other photo for that face. It sounds absolutely trivial to re-scan when the hash DB gets updated.