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The obvious reason why Facebook didn't go down this path is one of scale - It's easy (and altogether likely) for an attacker to pollute the hashes with innocuo
by ghshephard 9y ago
The obvious reason why Facebook didn't go down this path is one of scale - It's easy (and altogether likely) for an attacker to pollute the hashes with innocuous pictures. But, even more importantly, once you reveal your hashing system, it's relatively trivial for people to work around them and modify the pictures in such a way as to render the hashing system useless. Has to be done server side for these reasons.
- beager 9y agoIf “scale” is the reason they insist that explicit images be uploaded directly to them instead of hashed beforehand, then they really don’t care about this program enough to do it right. They can easily scale this by allowing hash uploads, using a trivial client side classifier to guess at whether an image is actually served well by this technology, and confirm positives with CV after a bad actor reposts their media on the site, with human intervention only on the fringes.
- theptip 9y agoCould you elaborate why you think it's easy to pollute hashes/fingerprints in this scheme? It seems to me that it would be hard to do reliably, since each hash submitted is going to be linked to an individual account. If an account submitted a bunch of hashes that matched non-explicit images, all further hash submissions from that user account could be rejected. (In the GP's proposed scheme a human can still verify a sample of all positive matches, to validate if they are true or false positives). I think the point about revealing your fingerprinting system is a good one. But I wonder if the equilibrium point would still be better than what we have now, i.e. unsophisticated posters would get caught, and sophisticated ones might not, vs. what we have now where there is no way to catch any of these posts.