How Does Smartphone Contact Tracing Work?

Things have definitely changed since the last time our society tackled a pandemic. Now we all carry around convenient tracking devices that make it easy to aggregate information and figure out how people move around and how often we’re in close proximity.

That’s exactly how traffic data is compiled for Google Maps and Apple Maps. as it happens. They track phones moving along a roadway and compare current device velocity versus statistical average; the slower the phones move, the more traffic there is. Ingenious, really.

In the old days contagious disease contact tracing was tedious, manual detective work: you’re sick? Who have you been in contact with in the last week or two, and who have they been in contact with?

Now it’s all automated.

But let’s be clear: Contact tracing does not constantly report your location to a central service so you can be tracked by some secretive government agency. It’s actually much more akin to how Find My Phone works on an iOS or Android device.

Nonetheless, the challenge with this modern technological contact tracking solution remains user privacy. None of us want the government tracking our every move and building massive databases of everyone with whom we’ve interacted. That’s why the foundation of the contract tracing solutions is a technology called Private Automated Contact Tracing (PACT).

PACT works through Bluetooth pings known as “chirps”. All phones send and receive these pings and your phone can constantly record the chirps from adjacent phones. If you then report that you’ve tested positive for Covid-19, the stored chirps from the last two weeks can then be uploaded, analyzed, the other devices identified and notifications then issued that alert them to the situation.

The bluetooth chirp ID to device mapping is the key privacy element, and that information is stored by national health organizations, not the FBI, NSA or any other law enforcement or government agency. No Illuminati, no shadowy government agency, no world gov’t.

Apple and Google also state that their code implementations are scrambling that identifying information and changing your phone’s tracing chirp ID every 10-15 minutes. If and when you receive a notification, it will also not include any identifying information about the person who has reported positive. Was it your roommate? Your Uncle Harry? Or the clerk at the local supermarket? You won’t have any way of knowing.

As of Wednesday, May 20, the latest updates to both Android and iPhone’s iOS include this contact tracing feature. If you don’t install the Centers for Disease Control CDC app [iOS link || Android link] or a similar authorized app, the contact tracing feature will remain disabled, however.

Hope that helps answer your questions about the technology. If you’d like to read more about the privacy aspects from health officials, engineers and privacy advocates, Google News has quite a lot of information on the subject.

Note: Screen captures, settings and notifications are mockups from Apple and Google and used to illustrate concepts. They are not necessarily exactly how things will appear when fully implemented and actively working.

Pro Tip: I’ve been writing about technology and privacy for quite a while. Please check out my computer basics help area for lots more tutorials of this nature. Thanks!