[seaofmars]

>Why haven't I made my whitepaper about PhotoDNA public? In my view, who would it help? It would help bad guys avoid detection and it will help malcontents manufacture false-positives.

I would suggest that the people NCMEC are most enthusiastic to catch know better than to post CSAM in places using PhotoDNA, particularly in a manner that may implicate them. Perhaps I overestimate them.