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Comment by edison112358 | Hacker News Reader

“This means that when the features are rolled out, a version of the NCMEC CSAM database will be uploaded onto every single iPhone.”

So every iPhone will now host the explicit images from the National Center for Missing & Exploited Children database.

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> No user receives any CSAM photo, not even in encrypted form. Users receive a data structure of blinded fingerprints of photos in the CSAM database. Users cannot recover these fingerprints and therefore cannot use them to identify which photos are in the CSAM database.

Source (PDF): https://www.apple.com/child-safety/pdf/Technical_Assessment_...

> So every iPhone will now host the explicit images from the National Center for Missing & Exploited Children database.

It's hashes, not the images themselves.

And how did the user end up with the hashes? He hashed the original images which he then deleted, your honor!

BTW this is going to be a major target for smearing people that the US doens't like

I'm sorry but this is the most ridiculous thing I've read today. Hashes have never and probably will never be used "smear" someone the US doesn't like. We can speculate about them planting evidence but trying to prosecute based on hashes baked into the OS used by millions? That's absurd.

I'm pretty sure this is a non-tech way of saying "a machine learning model" or other parameters which is not a particularly useful form of this database.

The database contains perceptual hashes, not images.

How long until a hacker uses ML to generate collisions against those hashes?

There is a minimum number of hash matches required, then images are made available to Apple who then manually checks that they are CSAM material and not just collisions. That's what the 9to5Mac story about this says: https://9to5mac.com/2021/08/05/apple-announces-new-protectio...

For what purpose? A collision doesn't mean that you found the source images. Not even close.

With a broader rollout to all accounts and simply scanning in iMessage rather than photos there's one possible scenario if you could generate images which were plausibly real photos: spam them to someone before an election, let friendly law enforcement talk about the investigation, and let them discover how hard it is to prove that you didn't delete the original image which was used to generate the fingerprint. Variations abound: target that teacher who gave you a bad grade, etc. The idea would be credibility laundering: “Apple flagged their phone” sounds more like there's something there than, say, a leak to the tabloids or a police investigation run by a political rival.

This is technically possible now but requires you to actually have access to seriously illegal material. A feasible collision process would make it a lot easier for someone to avoid having something which could directly result in a jail sentence.

So you can upload the colliding images to iCloud and get yourself reported for having child porn. Then after the law comes down on you, you can prove that you didn't ever have child porn. And you can sue Apple for libel, falsely reporting a crime, whatever else they did. It would be a clever bit of tech activism.

Find collisions, spam the colliding photos to people you don't like, watch the mayhem unfold.

Yes, everyone in jail! It’s probably just the md5 or something like that, but I don’t like it either.

No, they will host the hashes computed from those images.

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