The Clever Cryptography Behind Apple's 'Find My' Feature

When Apple executive Craig Federighi described a new location-tracking feature for Apple devices at the company's Worldwide Developer Conference keynote on Monday, it sounded—to the sufficiently paranoid, at least—like both a physical security innovation and a potential privacy disaster. In upcoming versions of iOS and macOS, the new Find My feature will broadcast Bluetooth signals from Apple devices even when they're offline, allowing nearby Apple devices to relay their location to the cloud. Matthew Green, Johns Hopkins University 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. 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.