Always-on Processor magic: How Find My works while iPhone is powered off

The first time I restarted my iPhone 13 Pro I saw this notice that Find My capabilities would continue to operate while the device was off. How? Well, it turns out there is a whole subsystem that does this stuff.

There's only little public documentation about the AOP. All chips and various embedded devices Apple manufactures run a real-time operating system, called RTKitOS. The AOP on the iPhone is no exception. However, the AOP has a special role. It connects to almost every other chip in the iPhone. For some chips, it only does basic tasks like power management, and for other chips, it acts as a transparent proxy that wakes up iOS when needed.

Super interesting. The security, cryptography, and privacy on much of this Find My infrastructure makes it very difficult to follow how these systems work.