“We have identified code within iOS 18 and higher that is an inactivity timer. This timer will cause devices in an AFU state to reboot to a BFU state after a set period of time which we have also identified.”-Christopher Vance, a forensic specialist, Magnet Forensics
Apple iPhone models in the After First Unlock (AFU) state have been unlocked by the user with a passcode since the last time the phone had been powered on. In that state, iPhones can be unlocked by a machine like the ones produced by Cellebrite. But rebooting the phones took them to the Before First Unlock (BFU) state where it becomes harder for those passcode cracking machines to crack the code and break into a phone.
“Remember that the real threat here is not police. It’s the kind of people who will steal your iPhone for malign purposes. This feature means that if your phone gets stolen, the thieves can’t nurse it along for months until they develop the tech to crack it.”-Matthew Green, cryptographer and associate professor, Johns Hopkins University
Those on the side of law enforcement might see this as a slap in the face by Apple because this new feature could prevent an iPhone from being used to collect enough evidence to lock someone up. But there is another way to look at it. The new feature prevents a criminal from stealing your iPhone and holding it until they figure out a way to unlock it.