Perceptual image hashes are a hard problem. Searching for subversive text strings is easy. And, a bunch of the obscuring-of-surveillance-intent achieved here i

Perceptual image hashes are a hard problem. Searching for subversive text strings is easy. And, a bunch of the obscuring-of-surveillance-intent achieved here is oblivious as to the types of detection-events - not at all image-specific. (That is, the private-set-intersection, cryptographic 'blinding', & threshold sharing schemes will work just fine for text/text-shingle/text-vector snitchlists as for image-perceptual-hash snitchlists. They're generic tricks for hiding what searches are being performed, & easy to repurpose.) Once Apple's shown a willingness to install iOS software that does a crime-grep on private data, & snitches on users without their assent, adding text-triggers is technically simple. A iOS point-release.