Photos in iOS 13 on an iPhone XS MaxSource: iMore

What you need to know

  • Apple's new on-device CSAM checks are only run on photos that are to be uploaded to iCloud Photos.
  • Photos aren't checked on devices with iCloud Photos disabled.
  • Apple also confirmed that it cannot check photos that are inside iCloud backups

Apple announced new on-device CSAM detection techniques yesterday as part of its new Child Safety measures, 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. 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.

So yeah, there you go.

Looking for another source of backups that are a little less cloud-based? Check out this collection of the best external hard drives for things like Time Machine!