THE PROBLEM — an offline item can't report itself

If you lose an AirTag, more than 1 billion strangers' iPhones quietly go looking for it on your behalf. Apple runs the network that pulls this off, and yet Apple itself can't see where your lost item is. So they launched offline finding in 2019, and it powers AirTag in 2021. It's the same system that powers AirTags. More than 1 billion active Apple devices act as one enormous crowd-sourced network. And it works even when you've lost thing is no internet connection. The mechanism is, say an offline item, say an AirTag on your keys or stolen MacBook, can't report its own location. So it broadcasts a Bluetooth low energy beacon carrying a rotating public key that rotates every so often, which stops anyone from using the signal to track it over time. And then any nearby Apple device, owned by a stranger, here's the beacon, reads its own GPS position, encrypts that position with the broadcast key, and uploads the sealed location and reports it back to Apple. So only your paired devices hold the matching private key, so only you can open it. And that private key, the payoff is a blind operator. Apple servers (relay only) 1B+ devices relaying, Apple sees 0 locations. Finder reports anonymous, no relay identity. Apple/finder - none. Private key - owner's paired devices only. Apple can't see the location the whole way, while still staying blind to it. You can build a system where even the company running it cannot see the data passing through its own hands and can't actually be a future.