In the real world, exact matching of image hash values won't work. It's routine for images to change in small ways over their lifetimes as they're shared. Acc

In the real world, exact matching of image hash values won't work. It's routine for images to change in small ways over their lifetimes as they're shared. According to the model you suggest, modifying a single pixel in the image by even the smallest amount would cause a hash mismatch against the original. If Apple's system is truly that inflexible, it will be trivial to circumvent in no time. Just increment / decrement a random RGB pixel in each of your images, and voila, your porn is scot free. Of course this countermeasure will be employed almost instantly by miscreants, so how will the FBI respond? Will they give up? Certainly not. They already have a blank check to spy on our phones. So they will devise a clumsier match algorithm that scans more sources of data on your phone and your cloud accounts and your backups, and produces more false positives. Why wouldn't they do this? Once any telecom service provider opens a door which compromises security or privacy, they will have a much harder time closing it.