When you install "Find My" – which must be done on at least two
devices – it generates a private key which is shared to all of your
Each device generates an additional public key, which is what your device broadcasts out via Bluetooth.
This public key changes itself periodically, making it more difficult for malicious parties to track your movements.
When another device picks up your signal, it uploads the encrypted location and a hash of the device's public key to the cloud.
you want to find your stolen device, your second Apple device, which
contains both the private and public key, uploads its version of the
public key to find the matching hash.
will return the encrypted location of the stolen device, and the second
device can then use its private key to encrypt a last-known destination.