[kccqzy]

The algorithm is actually public: https://www.apple.com/child-safety/pdf/Apple_PSI_System_Secu... From an intellectual point of view it's interesting to learn about.

I agree with the rest of your points. The problem is that we don't know if Apple implemented this algorithm correctly, or even this algorithm at all, because the source code isn't subject to review and, even it were the binary cannot be proved to have been built from such source code. We also don't have proof that the only images being searched for are child abuse images as they claim.