How Apple and Google Are Enabling Covid-19 Bluetooth Contact-Tracing | WIRED
▻https://www.wired.com/story/apple-google-bluetooth-contact-tracing-covid-19
Since Covid-19 began its spread across the world, technologists have proposed using so-called contact-tracing apps to track infections via smartphones. Now, Google and Apple are teaming up to give contact-tracers the ingredients to make that system possible—while in theory still preserving the privacy of those who use it.
On Friday, the two companies announced a rare joint project to create the groundwork for Bluetooth-based contact-tracing apps that can work across both iOS and Android phones. In mid-May, they plan to release an application programming interface that apps from public health organizations can tap into. The API will let those apps use a phone’s Bluetooth radios—which have a range of about 30 feet—to keep track of whether a smartphone’s owner has come into contact with someone who later turns out to have been infected with Covid-19. Once alerted, that user can then self-isolate or get tested themselves.
Several projects, including ones led by developers at MIT, Stanford, and the governments of Singapore and Germany, have already proposed, and in some cases implemented, similar Bluetooth-based contact-tracing systems. Google and Apple declined to say which specific groups or government agencies they’ve been working with. But they argue that by building operating-level functions those applications can tap into, the apps will be far more effective and energy efficient. Most importantly, they’ll be interoperable between the two dominant smartphone platforms.
In the version of the system set to roll out next month, the operating-system-level Bluetooth tracing would allow users to opt in to a Bluetooth-based proximity-detection scheme when they download a contact-tracing app. Their phone would then constantly ping out Bluetooth signals to others nearby while also listening for communications from nearby phones.
Until now, however, Bluetooth-based schemes like the one White described suffered from how Apple limits access to Bluetooth when apps run in the background of iOS, a privacy and power-saving safeguard. It will lift that restriction specifically for contact-tracing apps. And Apple and Google say that the protocol they’re releasing will be designed to use minimal power to save phones’ battery lives. “This thing has to run 24-7, so it has to really only sip the battery life,” said one of the project’s spokespeople.
In a second iteration of the system rolling out in June, Apple and Google say they’ll allow users to enable Bluetooth-based contact-tracing even without an app installed, building the system into the operating systems themselves. This would be opt-in as well. But while the phones would exchange “beacon” numbers via Bluetooth, users would still need to download a contact-tracing app to either declare themselves as Covid-19 positive or to learn if someone they’ve come into contact with was diagnosed.
Google and Apple’s Bluetooth-based system has some significant privacy advantages over GPS-based location-tracking systems that have been proposed by other researchers including at MIT, the University of Toronto, McGill, and Harvard. Since those systems collect location data, they would require complex cryptographic systems to avoid collecting information about users’ movements that could potentially expose highly personal information, from political dissent to extramarital affairs.
With Google and Apple’s announcement, it’s clear that the companies chose to skirt those privacy pitfalls and implement a system that collects no location data. “It looks like we won,” says Stanford’s White, whose Covid-Watch project, part of a consortium of projects using a Bluetooth-based system, had advocated for the Bluetooth-only approach. “It’s clear from the API that it was influenced by our work. It’s following the exact suggestions from our engineers about how implement it.”