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Comment by LeifCarrotson | Hacker News Reader

He carefully avoided saying that the image itself is the same. The exact fingerprint is the same, yes, but the fingerprint is just a hash of the actual image. Disinformation indeed!

The whole point of the system is that you get a matching hash after mirroring/rotating/distorting/cropping/compressing/transforming/watermarking the source image. The system would be pretty useless if it couldn't match an image after someone, say, added a watermark. And if the algorithm was public, it would be easy to bypass.

The concern, of course, is that all of this many-to-one hashing might also cause another unrelated image to generate the same fingerprint, and thereby throw an innocent person to an unyielding blankface bureaucracy who believes their black-box system without question.

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It simply means that they can have whatever the hell kind of method they use to identify specific images, and the scary part is: there IS an error-margin built-in because otherwise, as you said, this tech would be pretty useless.

"Find all images and tag them if they look like this fingerprint" doesn't mean that. It means: "Find all images and tag them if they look 80% like this fingerprint".

Which also means that it will allow governments to upload photographs of people's faces and say: "Tag anyone who looks like this".

Worse, this will allow China to track down more Uyghurs, find people based on guides in the form of images that are spread around to stay safe from the Chinese government, and countries like Saudi Arabia can start looking for phones with a significant amount of atheist-related images, tracking down atheists, and killing them. Because that's what that country does.

The CCP has had access to iCloud in China for multiple years...

https://www.reuters.com/article/us-china-apple-icloud-insigh...

These perceptual hashes do have high number of false positives. That's why they employ AI to discard images that don't have certain features from the pool to minimise the risk. But that method in general without actual human checking manually is a recipe for disaster.

This is why there’s a threshold of matches “on the order of 30+” before anything is sent to the system for further review.

> Apple decided to implement a similar process, but said it would do the image-matching on a user's iPhone or iPad, before it was uploaded to iCloud.

Is this list of hashes already public? If not, seems like adding it to every iPhone and iPad will make it public. I get the "privacy" angle of doing the checks client-side, but it's little like verifying your password client-side. I guess they aren't concerned about the bogeymen knowing with certainty which images will escape detection.

The hashes on device are encrypted. iPhone users do not have access to the unencrypted version.

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