Re:Apple enabling client-side CSAM scanning on iPhone tomorrow
by shuckles on Thursday August 05, 2021 @11:19AM
(#28074953)
The NCMEC hash list is private, and adversarial attacks require running gradient descent and being able to generate a hash value for arbitrary input.
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Re:Apple enabling client-side CSAM scanning on iPhone tomorrow
by josephcsible on Thursday August 05, 2021 @07:07PM
(#28081241)
At least one of these two things must be true: either Apple is going to upload hashes of every image on your device to someone else's server, or the database of hashes will be available somehow to your device.
Re:Apple enabling client-side CSAM scanning on iPhone tomorrow
by josephcsible on Saturday August 07, 2021 @11:42PM
(#28104042)
Turns out there's a third option I wasn't thinking about: private set intersection.
Re:Apple enabling client-side CSAM scanning on iPhone tomorrow
by shrimpx on Thursday August 05, 2021 @09:16PM
(#28082163)
Is it possible to narrow in on a hash using gradient descent? You can correlate distance between inputs to distance between hashes somehow?
Re:Apple enabling client-side CSAM scanning on iPhone tomorrow
by shrimpx on Friday August 06, 2021 @08:46PM
(#28094548)
Replying to my own question since I can’t edit anymore: it turns out “perceptual hashing,” which I didn’t know much about, has exactly this property, that small changes in the input result in small changes in the output.