> "If Apple’s CSAM scanner was deployed today, it would be scanning those photos in cleartext on your phone before unreadable data was sent up to the cloud."
Or enabling Advanced Data Protection could have disabled the scanner, we don't know. Even if it went the way you said, you could still not use iCloud and have private photos on your device, whereas your phrasing is trying to imply that there would be no option to do that.
I guess back in 2021 we had to pretend to believe things like that, because Apple hadn’t yet announced ADP and was refusing to admit they planned an encryption rollout. But they’ve gone and rolled ADP out now: we can stop pretending to believe silly things. Obviously ADP was being planned, and obviously the CSAM scanner was intended to work with it. It got dropped due to the public backlash. A relatively short 16 months later ADP rolled out without it. End of story.
If it pleases you to believe that Apple designed a scanning system that just happened to work with encrypted backup, but intended to turn it off for users who enabled encrypted backup… go ahead and believe that. I would just say, in the most polite way, that maybe if the positive case for Apple’s CSAM proposal requires one to believe such unlikely things, perhaps it is not a very strong case at all.
[1] https://www.reuters.com/article/us-apple-fbi-icloud-exclusiv...
It did a great job at freaking people out hearing about their photos getting scanned and it could be defeated by making a 1 pixel change to any photos a pedo would hide on their phone (since any changes to the image would totally change the hash).
This isn't the way those hashes work. A 1 pixel change would still hash similar enough to be matched. Maybe there are adversarial 1 pixel changes that could break the hashing, but I doubt it.
Even cropping, watermarks and other manipulations like that would still match. "Perceptual hashing", very different to cryptographic hashing. It's basically checking if an image looks "similar enough".
I believe this is why they needed multiple matches, because otherwise there must have been too many false positives.
This may be too oversimplified, but imagine that in a series of CSAM images, there might be, for example, a wall or furniture or something, that could appear similar enough to a wall in one of your own photos. That's a match, off to the gulag with you!
Since late 2022 Apple has enabled Advanced Data Protection, which encrypts all photos before they’re uploaded to cloud storage. With ADP on, my photo library is “private” not just in the common-language sense (it contains extremely personal data I have not shared with others) but also in an opinionated technical sense that these files are accessible only to me. If Apple’s CSAM scanner was deployed today, it would be scanning those photos in cleartext on your phone before unreadable data was sent up to the cloud. You could argue that Apple was saying “hey, it doesn’t matter whether we can read the private data you’re storing, the price of sending even unreadable encrypted private data to our infrastructure is that you must run local software that scans the private photos on your phone,” but I think it’s extremely important to say it this way and not play language games. Apple was going to mandate local scanning of private photos as the cost of using their infrastructure even to store opaque private bits.