How Apple’s new ‘Find My’ app in iOS 13 and macOS Catalina works – and works securely

Juli Clover for MacRumors:

Apple at WWDC unveiled a new “Find My” app, which is available across its Mac and iOS platforms. Find My on iOS replaces Find My Friends and Find My iPhone, and on Mac, it introduces a native “Find” app for the first time as an alternative to using iCloud on the web.

Find My has a useful feature that’s designed to let you locate your lost devices even when they’re not connected to WiFi or a cellular network by leveraging nearby Bluetooth devices. Your lost iPhone, iPad, or Mac will be able to communicate via Bluetooth with any nearby Apple device, relaying its location right back to you.

Apple designed the Find My feature with privacy in mind. It uses an encryption system that prevents people from abusing it for tracking purposes, making your personal location unavailable to people aiming to intercept your device’s Bluetooth signal and from Apple itself.

Andy Greenberg for WIRED:

In a background phone call with WIRED following its keynote, Apple broke down that privacy element, explaining how its “encrypted and anonymous” system avoids leaking your location data willy nilly, even as your devices broadcast a Bluetooth signal explicitly designed to let you track your device. 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.

That system would obviate the threat of marketers or other snoops tracking Apple device Bluetooth signals, allowing them to build their own histories of every user’s location. “If Apple did things right, and there are a lot of ifs here, it sounds like this could be done in a private way,” says Matthew Green, a cryptographer at Johns Hopkins University. “Even if I tracked you walking around, I wouldn’t be able to recognize you were the same person from one hour to the next.”

In fact, Find My’s cryptography goes one step further than that, denying even Apple itself the ability to learn a user’s locations based on their Bluetooth beacons.

MacDailyNews Take: Reading Wired’s description of how the new system works, as Apple describes it, the new Find My system seems very secure.

Having a dedicated app also promises to speed things up. Family members how misplace their iPhone and need them before running out the door have little patience for navigating to iCloud.com, launching Find My iPhone, locating the device, then sending the ping sound. It takes too long on the Mac and we’ll be happy to be able to “Find My” much faster!

2 Comments

  1. This is a very cool idea. Obligatory : I wonder who Apple bought/stole it from.

    Implementation seems tricky — particularly in big cities, Apple’s “find me” database is going to be receiving dozens of reports for every apple device (let’s say there are a million in NYC) per second.

    They seem interested only in dealing with the latest, so for any given public key hash, they may store only the most recent, but depending on how often that public key changes… if it’s every 15 mins, that’s as many as 96 stored locations per device per day X their retention period (30 days?)

    It’s not nothing.

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