Wired’s Andy Greenberg shares more information about the technology behind the new Find My app, which lets you locate your devices even if they’re offline. It is, frankly, bananas:
The solution to that paradox, it turns out, is a trick that requires you to own at least two Apple devices. Each one emits a constantly changing key that nearby Apple devices use to encrypt and upload your geolocation data, such that only the other Apple device you own possesses the key to decrypt those locations.
Not explicitly mentioned in this story is another fact that makes this system feasible: the sheer volume of Apple devices that are out in the world, essentially creating a gigantic ad hoc mesh network. But Apple has clearly taken pains to prevent abuse of that power—or, in other words, they’re Lucius Fox at the end of The Dark Knight.