3 ms·

The invocation of 30 images like it's a barrier confuses me. I created a bunch of preimages posted on github, I could easily create 30 or 3000 but at this poin

by nullc 5y ago

The invocation of 30 images like it's a barrier confuses me. I created a bunch of preimages posted on github, I could easily create 30 or 3000 but at this point all I'd be doing is helping apple cover up their bad hash algorithm[1]. I pointed out above that the attacker could use legal pornography images selected to make it look like child porn. This isn't hard. Doing it 30 times is no particular challenge. I didn't use pornographic images in the examples I created out of good taste, not because it would be any harder. [1] I've made a statement that I won't be posting any more preimages for now for that reason: https://github.com/AsuharietYgvar/AppleNeuralHash2ONNX/issues/1#issuecomment-903178370 https://github.com/AsuharietYgvar/AppleNeuralHash2ONNX/issue...

simondotau 5y ago
If someone is trying to frame a known individual, the 30 image threshold may not be a significant barrier, I'll grant you that. But if you're enlisting Apple's algorithm to perform a dragnet search of the citizenry (e.g. leaked state secrets) then this mechanism cannot be effective unless the material in question is comprised of at least 30 photographs.
- nullc 5y ago
  I'll grant you that! I have some residual nitpicks, on that point: many leaked data troves are much larger than that, though it is a material restriction. The 30 threshold isn't leakless. Say you only have one hit, it still gets reported to Apple. The software also emits a small rate of "chaff", fake hits to help obscure the sub-threshold real hits. But it could still be used to produce a list of possible matches, including anyone with targeted material plus people who emitted fake matches, producing a list of potential targets much smaller than the whole population, for enhanced surveillance.
  - simondotau 5y ago
    This still relies upon some degree of compliance by Apple in order to acquire the stream of vouchers. Or alternatively a working security breach of Apple's systems. Either way this represents an additional, non-trivial barrier to overcome. It would be interesting to know what the "chaff" rate is and whether any intelligence agency could stomach that amount of surveillance, particularly since it's by no means certain that any of them are real. In fact it seems to me that it's very unlikely indeed, especially if the material is in any way radioactive. After all, finding a match this way requires quite a few assumptions: 1. The target owns an iPhone; 2. The target has enabled iCloud Photo Library; 3. The target has a photo library small enough, or is paying for sufficient iCloud storage space, that the flagged images are included in the (sub)set stored in the cloud; 4. The target has imported the flagged images into their photo library rather than to iCloud Drive or any third party app like SpiderOak, Mega or Tresorit.

by nullc 5y ago

simondotau 5y ago

If someone is trying to frame a known individual, the 30 image threshold may not be a significant barrier, I'll grant you that. But if you're enlisting Apple's algorithm to perform a dragnet search of the citizenry (e.g. leaked state secrets) then this mechanism cannot be effective unless the material in question is comprised of at least 30 photographs.

nullc 5y ago
I'll grant you that! I have some residual nitpicks, on that point: many leaked data troves are much larger than that, though it is a material restriction. The 30 threshold isn't leakless. Say you only have one hit, it still gets reported to Apple. The software also emits a small rate of "chaff", fake hits to help obscure the sub-threshold real hits. But it could still be used to produce a list of possible matches, including anyone with targeted material plus people who emitted fake matches, producing a list of potential targets much smaller than the whole population, for enhanced surveillance.
- simondotau 5y ago
  This still relies upon some degree of compliance by Apple in order to acquire the stream of vouchers. Or alternatively a working security breach of Apple's systems. Either way this represents an additional, non-trivial barrier to overcome. It would be interesting to know what the "chaff" rate is and whether any intelligence agency could stomach that amount of surveillance, particularly since it's by no means certain that any of them are real. In fact it seems to me that it's very unlikely indeed, especially if the material is in any way radioactive. After all, finding a match this way requires quite a few assumptions: 1. The target owns an iPhone; 2. The target has enabled iCloud Photo Library; 3. The target has a photo library small enough, or is paying for sufficient iCloud storage space, that the flagged images are included in the (sub)set stored in the cloud; 4. The target has imported the flagged images into their photo library rather than to iCloud Drive or any third party app like SpiderOak, Mega or Tresorit.