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0 pointsaeternum4y ago0 comments

As-if you can ever actually hash a biometric and expect it to match in the future. The whole idea of a hash is that a tiny perturbation makes the output completely different.

It almost by definition cannot work for biometrics.

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thebean114y ago

https://support.apple.com/en-us/HT204587

> Touch ID doesn't store any images of your fingerprint, and instead relies only on a mathematical representation. It isn't possible for someone to reverse engineer your actual fingerprint image from this stored data.

aeternumOP4y ago

Remember when Apple claimed similar about their CSAM photo-scanning but then it turned out it was pretty easy to generate a hash collision?

AFAIK Apple has not opened their TouchID hash scheme so you must take them at their word that it cannot be reverse engineered.

thebean114y ago

Sure, I think there are a million attack vectors for getting these "orbs" to send the same person money multiple times. Crafting a face that doesn't generate a hash collision (which would be the goal here) is probably an even easier problem!

I'm just pointing out that perceptual hashes do exist.

tomesco4y ago

> The whole idea of a hash is that a tiny perturbation makes the output completely different.

That would be a cryptographic hash you are describing. Not all hash functions share that property. As long as arbitrary input is mapped to a fixed size output it is a hash function. For example see NeuralHash [1] which is a hash function designed to be "insensitive to small changes in the input image."

[1] https://towardsdatascience.com/apples-neuralhash-how-it-work...

aeternumOP4y ago

If it's insensitive to small changes in the input image then it leaks substantial information about that input image.

have_faith4y ago

Perceptual hashes have the opposite set of traits (similar inputs produce similar outputs).

sam0x174y ago

there are also these things called perceptual hashes that are designed to get the same hash for similar inputs, where "similar" is domain-specific.

j / k navigate · click thread line to collapse

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thebean114y ago

https://support.apple.com/en-us/HT204587

aeternumOP4y ago

Remember when Apple claimed similar about their CSAM photo-scanning but then it turned out it was pretty easy to generate a hash collision?

AFAIK Apple has not opened their TouchID hash scheme so you must take them at their word that it cannot be reverse engineered.

thebean114y ago

I'm just pointing out that perceptual hashes do exist.

tomesco4y ago

> The whole idea of a hash is that a tiny perturbation makes the output completely different.

[1] https://towardsdatascience.com/apples-neuralhash-how-it-work...

aeternumOP4y ago

If it's insensitive to small changes in the input image then it leaks substantial information about that input image.

have_faith4y ago

Perceptual hashes have the opposite set of traits (similar inputs produce similar outputs).

sam0x174y ago

there are also these things called perceptual hashes that are designed to get the same hash for similar inputs, where "similar" is domain-specific.

j / k navigate · click thread line to collapse