I don’t like that system, but according to their summary document, CSAM detection system is only (as described today) processing images that are uploaded to iCloud.
[1] https://www.apple.com/child-safety/pdf/Expanded_Protections_...
[1] https://www.apple.com/child-safety/pdf/Expanded_Protections_...
And look at the diagram. The matching of image hashes with user photos occurs "on device."
I just think that there are better arguments against it without unnecessary exaggeration. So I wanted to be more specific on which images on your device are scanned according to that paper.
Obviously I should have phrased is better, like “about to be uploaded to iCloud”…
Just to spell this out (since I think this thread could still be a little confusing):
1. The photo scanning does occur on the device, not in the cloud. However,
2. Apple's explanation indicates that this device-based scanning will only occur on photos that may be uploaded to iCloud.