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This could happen with a perturbed image, but I doubt it. Apple will send the suspicious images to the relevant authorities. Those authorities will then look at

This could happen with a perturbed image, but I doubt it. Apple will send the suspicious images to the relevant authorities. Those authorities will then look at the images. The chances are low that they will then seek a search, even though the images are innocent upon visual inspection. But maybe in some places a ping from Apple is good enough for a search and seizure.

Kalium 5y ago
In broad strokes, I agree with you. I think you're absolutely correct that most trained, educated, technologically sophisticated law enforcement bodies will do exactly as you suggest and decide that there's not enough to investigate. That said, I'm not willing to say it won't happen. There are too many law enforcement entities of wildly varying levels of professionalism, staffing, and technical sophistication. Someone innocent, somewhere, is likely to have a multi-year legal drama because their local PD got an email from Apple. And we haven't even gotten to subjects like how some LEOs will happily plant evidence once they decide you're guilty.
falcolas 5y ago
FWIW, they won't send the images. Even in the pursuit of knocking back CSAM, there are strict restrictions on the transmission and viewing of CSAM - in some cases even the defendant's lawyers don't usually see the images themselves in preparation for a trial, just a description of the contents. Apple employees or contractors will likely not look at the images themselves, only visual hashes. They will instead contact the police and say "Person X has Y images that are on list Z," and let the police get a warrant based off that information and execute it to check for actual CSAM.
- topynate 5y ago
  On reflection, yes, there must be warrants involved. I'm raising my estimate of how likely it is that innocent people get raided due to this. The warrant would properly only be to search iCloud, not some guy's house, but I can easily see overly-broad warrants being issued.
  - gowld 5y ago
    > The warrant would properly only be to search iCloud, iCloud is encrypted, so that warrant is useless. They need to unlock and search the device.
    - topynate 5y ago
      Yes, it's encrypted, but part of this anti-CSAM strategy is a threshold encryption scheme that allows Apple to decrypt photos if a certain number of them have suspicious hashes.
      - Kalium 5y ago
        Apple having any kind of ability to decrypt user contents is disconcerting. It means they can be subpoenaed for that information.
        heavyset_go 5y ago
        > It means they can be subpoenaed for that information. They regularly are, and they regularly give up customer data in order to comply with subpeonas[1]. They give up customer data in response to government requests for 150,000 users/accounts a year[1]. [1] https://www.apple.com/legal/transparency/us.html https://www.apple.com/legal/transparency/us.html
      - bbatsell 5y ago
        No, the threshold encryption only allows for the 30+ cryptographic “vouchers” to be unlocked, which contain details about the hash matching as well as a “visual derivative” of the image. We don’t know any details about the visual derivative.
        sudosysgen 5y ago
        Im guessing the visual derivative is a difference of sorts between the image and the CSAM? Of course not sure.
- __blockcipher__ 5y ago
  > in some cases even the defendant's lawyers don't usually see the images themselves in preparation for a trial, just a description of the contents Man that seems horrible. So you just have to trust the description is accurate? You’d think there’d at least be a “private viewing room” type thing (I get the obvious concern of not giving them a file to take home)

Kalium 5y ago

In broad strokes, I agree with you. I think you're absolutely correct that most trained, educated, technologically sophisticated law enforcement bodies will do exactly as you suggest and decide that there's not enough to investigate. That said, I'm not willing to say it won't happen. There are too many law enforcement entities of wildly varying levels of professionalism, staffing, and technical sophistication. Someone innocent, somewhere, is likely to have a multi-year legal drama because their local PD got an email from Apple. And we haven't even gotten to subjects like how some LEOs will happily plant evidence once they decide you're guilty.

falcolas 5y ago

FWIW, they won't send the images. Even in the pursuit of knocking back CSAM, there are strict restrictions on the transmission and viewing of CSAM - in some cases even the defendant's lawyers don't usually see the images themselves in preparation for a trial, just a description of the contents. Apple employees or contractors will likely not look at the images themselves, only visual hashes. They will instead contact the police and say "Person X has Y images that are on list Z," and let the police get a warrant based off that information and execute it to check for actual CSAM.

topynate 5y ago
On reflection, yes, there must be warrants involved. I'm raising my estimate of how likely it is that innocent people get raided due to this. The warrant would properly only be to search iCloud, not some guy's house, but I can easily see overly-broad warrants being issued.
- gowld 5y ago
  > The warrant would properly only be to search iCloud, iCloud is encrypted, so that warrant is useless. They need to unlock and search the device.
  - topynate 5y ago
    Yes, it's encrypted, but part of this anti-CSAM strategy is a threshold encryption scheme that allows Apple to decrypt photos if a certain number of them have suspicious hashes.
    - Kalium 5y ago
      Apple having any kind of ability to decrypt user contents is disconcerting. It means they can be subpoenaed for that information.
      - heavyset_go 5y ago
        > It means they can be subpoenaed for that information. They regularly are, and they regularly give up customer data in order to comply with subpeonas[1]. They give up customer data in response to government requests for 150,000 users/accounts a year[1]. [1] https://www.apple.com/legal/transparency/us.html https://www.apple.com/legal/transparency/us.html
    - bbatsell 5y ago
      No, the threshold encryption only allows for the 30+ cryptographic “vouchers” to be unlocked, which contain details about the hash matching as well as a “visual derivative” of the image. We don’t know any details about the visual derivative.
      - sudosysgen 5y ago
        Im guessing the visual derivative is a difference of sorts between the image and the CSAM? Of course not sure.
__blockcipher__ 5y ago
> in some cases even the defendant's lawyers don't usually see the images themselves in preparation for a trial, just a description of the contents Man that seems horrible. So you just have to trust the description is accurate? You’d think there’d at least be a “private viewing room” type thing (I get the obvious concern of not giving them a file to take home)