PSA: Apple Can't Run CSAM Checks On Devices With iCloud Photos Turned Off

An anonymous reader quotes a report from iMore: Apple announced new on-device CSAM detection techniques yesterday and there has been a lot of confusion over what the feature can and cannot do. Contrary to what some people believe, Apple cannot check images when users have iCloud Photos disabled. Apple's confirmation of the new CSAM change did attempt to make this clear, but perhaps didn't make as good a job of it as it could. With millions upon millions of iPhone users around the world, it's to be expected that some could be confused.

'Using another technology called threshold secret sharing, the system ensures the contents of the safety vouchers cannot be interpreted by Apple unless the iCloud Photos account crosses a threshold of known CSAM content,' says Apple. 'The threshold is set to provide an extremely high level of accuracy and ensures less than a one in one trillion chance per year of incorrectly flagging a given account.' The key part there is the iCloud Photos bit because CSAM checks will only be carried out on devices that have that feature enabled. Any device with it disabled will not have its images checked. That's also a fact that MacRumors had confirmed, too. Something else that's been confirmed -- Apple can't delve into iCloud backups and check the images that are stored there, either. That means the only time Apple will run CSAM checks on photos is when it's getting ready to upload them to iCloud Photos.

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