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There are a lot of really valid criticisms of Apple plan here, but Apple has gone out of their way to prevent that exact case. Apple is using secret splitting
by theluketaylor 5y ago
There are a lot of really valid criticisms of Apple plan here, but Apple has gone out of their way to prevent that exact case. Apple is using secret splitting to make sure they cannot decode the CSAM ticket until the threshold is reached. Devices also produce some synthetic matches to prevent themselves Apple (or anyone else) inferring a pre-threshold count based on the number of vouchers.
https://www.apple.com/child-safety/pdf/CSAM_Detection_Technical_Summary.pdf https://www.apple.com/child-safety/pdf/CSAM_Detection_Techni...
Threshold Secret Sharing
Synthetic Match Vouchers
- zug_zug 5y agoThanks. You're right. Very sophisticated system. Still find it morally repugnant, but technologically it is fairly thorough.
- heavyset_go 5y ago> There are a lot of really valid criticisms of Apple plan here, but Apple has gone out of their way to prevent that exact case. Not they haven't. The files are still uploaded to Apple's servers where Apple holds their encryption keys. Apple or the FBI could scan the photos for CSAM whenever they want to.
- theluketaylor 5y agoThe contortions apple is going through to scan locally only really make sense if they are gearing up to do end to end encryption of iCloud photos. I imagine they have other prerequisites before they are ready to announce that as a feature, but if they are not planning to encrypt more why wouldn’t they just scan in the cloud?