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Comment by 1_2__4 | Hacker News Reader

Do you have a better idea? I don’t.

Hash your copy of the nude image client side, and upload the hash only? Seems like a way better idea to me.

A hash would only match an identical file, right? It sounds like image recognition is used here to catch derivatives of the original file, which a hash wouldn't catch.

I think it would be easy to create multiple hashes (reverse, flipped, etc...) and upload them all and look for matches. Provide the users with image recognition signature creating software (which is exactly what they are going to do) and let the users do it, vs uploading extremely personal and potentially embarrassing images to strangers on the internet.

How about recompressed, resized, photoshopped, format-converted... a filter against trivial transformations like transposition is worthless.

tough problem sure, but sending nude photos to a morally questionable company is not remotely close to the best solution to this problem.

If someone has your nudes and intends to share them I think blocking them only on Facebook and not anywhere else is not productive.

You should just post the nudes yourself IMHO and be done with it.

^High School (and below) sure would be interesting /s

I imagine for most people in most situations regarding their* unwanted explicit media being published, the opposite is true i.e. Facebook(social media) is the worst place for it to be

then don't send them, but don't complain about facebook allowing your nudes to be posted. I don't think Facebook is going to open source their image recognition algorithm just because you want it to.

You do have a choice, use the service or not. If I ever found out a nude picture of me was leaked, I'd definitely trust FB more than whoever took it and leaked it in the first place. The whole point of the service is pretty much: your picture is already or about to be out there.

It's called a perceptual hash, and there is a lot of research in this area.

There are specific (non-cryptographic) hashes which are built to compare equal for equal data, and to be similar for similar data (for different metrics of similarity). It's a somewhat esoteric subject, but it's a thing.

The "hash" would have to be non-reversible. When we compare images based on content, afaik we transfer them into a vector space and measure distance. Do we really have tech to make and compare such a content representation in a non-reversible way? That sounds like a lot to ask for tech that seems still in active development.

All hashes are non-reversible. Being one way is one of the characteristics of a hash. Depending on how effective it is, there may be collisions possible. This is kind of happened with previously common hashes like md5 where people were able to break it by generating collisions.

But basically saying “as long as it is unreversable” is redundant unless you think there’s some reason to think the hash sucks.

If your hash is smaller than the (compressed) image itself, then you have information-theoretical loss; there is no possible way to reverse the operation. And these hashes are usually much smaller than the original.

Good thing most people know how to make a hash.

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