Do the people authorized to query the database have access to view its contents?

How many people in the world can certify that it only contains CSAM? I wonder if there are images of US troops committing warcrimes, or politicians doing cocaine, or honeypot intel op blackmail images in there too. Lots of powerful people would love to have an early warning system for leaks of embarrassing non-CSAM images.

Matt should read the release before live tweeting FUD. The database is shipped in the iOS image, per the overview, so targeting users is not an issue (roughly).

Is the database frozen or can they push out updates independently of iOS updates? If not, targeting individual users definitely doesn't seem possible unless you control OS signing.

The database is shipped in the iOS image.

That's what you wrote originally - and to me it doesn't indicate whether it can also be updated from other sources or not.

Lots of content is shipped in the iOS image but can update independently.

The technical summary provides a lot of detail. I don’t think Apple would omit remote update functionality from it if such capability existed, especially since database poisoning is a real risk to this type of program. I’m comfortable with interpreting the lack of evidence as evidence of absence of such a mechanism. Explicit clarification would certainly help though, but my original point stands: there is positive evidence in the docs which the FUD tweets don’t engage with.

In particular, I’m referencing the figure which says that the database of CSAM hashes is “Blinded and embedded” into the client device. That does not sound like an asset the system remotely updates.

Do you not see any scenerio where the CIA/OGA inserts a hash into the database to specially target one person or a group of people?

I agree database poisoning is a legitimate threat! Including the database in an iOS release (so it can’t be targeted and updated out of band) mitigates it somewhat. At the end of the day, though, more should be done to make NCMEC’s database transparent and trustworthy. And other databases too, if Apple decides to ship country-specific blacklists.

I personally don't believe this process can be made to be trustworthy enough while still serving its stated purpose. It will always remain opaque enough that it could and will be used to violate civil rights.

I don’t see how this system is particularly less trustworthy than the existing system of iOS updates.

You should understand the difference between a protocol and an easy to change implementation detail before throwing around words like FUD.

Has Matt redacted any of the FUD from his tweets last night which aren’t true given the published details from today? For example, his claim that the method is vulnerable to black box attacks from GANs isn’t applicable to the protocol because the attacker can’t access model outputs.

Furthermore, if “an easy to change implementation detail” in your threat model is anything which could be changed by iOS update, you should’ve stopped using iPhone about 14 years ago.