FastCompancy, from the interview with Kaiann Drance, Apple’s VP of worldwide iPhone product marketing, and Ron Huang, senior director of sensing and connectivity:
AirTags don’t rely on an internet connection of their own. Instead, they piggyback off of a network of almost a billion iOS devices and Macs already out in the world. Each AirTag sends out a unique encrypted Bluetooth identifier; other Apple devices can detect it and relay the location of the AirTag directly to an owner’s Apple ID account.
And:
This entire process is end-to-end encrypted so that no one but the owner of the AirTag—not the owners of the crowdsourced devices picking up the AirTag’s location or even Apple itself—ever has access to the AirTag’s current or past location. And the Bluetooth identifiers that AirTags emit are not only randomized but “are rotated many times a day and never reused so that as you travel from place to place with the AirTag, you cannot be re-identified,” Huang says.
And:
The AirTag owner can never see which devices its AirTag’s location is pinging off of or who owns those devices.
And:
Every AirTag has a unique serial number printed on it, but the identity of the owner cannot be derived from that number unless that owner activates the AirTag’s Lost Mode. That’s a toggle in the Find My app that marks your AirTag as lost. Once you’ve toggled that option on, someone who finds your lost AirTag can then scan it with any NFC-equipped device (such as an iPhone or Android phone) to display a web URL prompt on that device. Tapping on the prompt will take the finder of your AirTag to an Apple support page featuring the AirTag’s unique serial number and—if the AirTag owner so chooses—the phone number of the AirTag’s owner so the finder can call or text.
And:
If you’re an iPhone owner running iOS 14.5 or later and someone slips an AirTag into your possession in secret in order to track your movements, your iPhone will warn you this has happened by sending you an “AirTag Found Moving With You” notification. This notification will appear only when an AirTag is following you that is not paired with your Apple ID or another iPhone that is in your vicinity. That distinction is critical so that your iPhone won’t be notified of AirTags that, for instance, belong to other people on the same bus you’re riding.
This whole interview is a riveting read, full of insight into how AirTags work and showing off how much thought Apple put into the privacy and safety aspects. Learned a lot reading this.