Apple themselves addressed "why", summarized here: https://news.ycombinator.com/item?id=28176418 https://news.ycombinator.com/item?id=28176418 The facts remai

Apple themselves addressed "why", summarized here: https://news.ycombinator.com/item?id=28176418 https://news.ycombinator.com/item?id=28176418 The facts remain that: a) Apple's new system is strictly superior to PhotoDNA in every respect people complain about, including malicious insertions of non-CSAM hashes (since you'd need 30 matches with Apple, and 1 with every other online service); and b) concerns about the local implementation mostly rely on fear of the unknown and illogical arguments (Apple's system makes it no more likely than before that we'll see backdoors in their OSes, and if that ever happens researchers would certainly discover it).