The thing I can publicly say is that the database is not strictly for illegal or even borderline imagery.
NCMEC try to keep the contents, processes and access to the database under wraps for obvious reasons.
By both a legal and moralistic standard they're not CSAM. Not even nearly.
Of course, this is a minority of the content in the database. But even 1 such image is gross neglect of stated purpose in my book.
Why would I have any content in my phone that would be in that database?
- A kitchen with nobody in frame.
- A couch with nobody in frame.
- Outdoor scenery with nobody in frame.
- A bathroom with nobody in frame.
Is it hard to believe you wouldn't download something like this without knowing where it came from?
I'm not talking about borderline stuff. I'm talking about content that has not even a hint of pornography or illegality.
Remember, these databases are essentially signature DB's, and there is no guarantee that all hashes are just doing a naive match on the entire file, or that all scans performedare fundamentally the same.
This is why I reject outright the legitimacy of any Client-based CSAM scanners. In a closed source environment, it's yet another blob, therefore an arbitrary code execution vector.
I'm sorry, but in my calculus, I'm not willing to buy into that, even for CSAM. It won't stay just filesystems. It won't stay just hash matching. The fact there's so much secrecy around ways and means implies there's likely dynamicity in what they are looking for, and with the permissions and sensors on a phone that many apps already ask for, my not one inch instincts are sadly firmly engaged with no signs of letting up.
I'm totally behind the fight. I'm not an idiot though, and I know what the road to hell is paved with. Law Enforcement and anti-CSAM agencies are cut a lot of slack, and enjoy a lot of unquestioning acceptance by the populace. In my book, this warrants more scrutiny, and caution not less. The rash of inconvenient people being rather frequently called out as having CSAM found on hard drives in media with no additional context indicates the CSAM definition is being wielded in a manner that produces a great degree of political convenience.
Again, more scrutiny, not less.
In principle, the OS environment could be made independently auditable - keeping undeleteable signed logs.
A person who creates CSAM likely doesn't just create CSAM all the time, right? Those innocuous pictures get lumped together with illegal content and make it into the database.
The database is a mess, basically. Of course it is. It's gigantic beyond your wildest estimates.