Apple quietly introduced code into iOS 18.1 which reboots the device if it has not been unlocked for a period of time, reverting it to a state which improves the security of iPhones overall and is making it harder for police to break into the devices, according to multiple iPhone security experts.
On Thursday, 404 Media reported that law enforcement officials were freaking out that iPhones which had been stored for examination were mysteriously rebooting themselves. At the time the cause was unclear, with the officials only able to speculate why they were being locked out of the devices. Now a day later, the potential reason why is coming into view.
“Apple indeed added a feature called ‘inactivity reboot’ in iOS 18.1.,” Dr.-Ing. Jiska Classen, a research group leader at the Hasso Plattner Institute, tweeted after 404 Media published on Thursday along with screenshots that they presented as the relevant pieces of code.
Although lockdown mode is a good step and helps defend against biometric warrents, it does not wipe the encryption keys from RAM. This can only be achieved by using a secondary (non-default) user profile on GrapheneOS, and triggering the End session feature. This fully removes the cryptographic secrets from memory, and requires the PIN or password to unlock, which is enforced through the StrongBox and Weaver API of the Titan M2 secure element in Pixel devices.