COVID-19: Google and Apple reveal more intriguing details of contact-tracing.

Contact-tracing is the heart of a new app being developed for iPhones and Android handsets, through a ground-breaking collaboration between Apple and Google.

In conversation with both Apple and Google earlier today, I have been told more details of how things are going to work, logistically and technologically, to help in the fight against COVID-19. The API that is being developed aims to overcome one of the main issues with contact-tracing technology: the lack of interoperability. So, Apple and Google were keen to emphasize that they are building interoperability at device level in Phase 1, which is underway now. Users download an app and opt in for the contact-tracing to work.

The way the app works uses Bluetooth Low Energy. Each smartphone with the app spots when another phone is nearby and each exchanges anonymous identifier beacons, which change often. The data they exchange does not contain location information and is unusable to anyone, except when the identifier is needed again. So, if you spend, say, 15 minutes in close contact with someone, friend or stranger, the phones do their little exchange procedure. If one of the two people later contracts COVID-19 – and is diagnosed and positively tested – they enter this information in the Public Health Authority’s app. Then, providing the user consents, the last two weeks’ of beacons to the server. The final stage in the process is that the phones have come into contact with the now-diagnosed user receive an alert. This tells them they’ve come into contact with someone with the disease, with instructions on how to seek more information. Of course, everyone needs to have the app on their phone for this to work.

However, where things get even more interesting is in Phase 2, where the tracing functionality is built in without the need to download an app. With contact-tracing, a certain proportion of users need to have the function on their phone for it to work. Take away the need to download the app and you’ve overcome a bump in the road. Nonetheless, both companies made clear that at every point, there is privacy and complete user control.

Crucial to the whole process is the fact that it is only the health authorities which can access this data – Apple and Google will have a whitelist that ensures the data isn’t misused.

My first worry was that it wouldn’t be widely available. I’m told that every phone that uses iOS 13 will be compatible, which is every iPhone since the iPhone 6s, released in September 2015. And Google will make it available for phones going back as far as Android 6, which we used to call Marshmallow, and which was released in Fall 2015, too.

How about battery life, though? Some of those phones aren’t known for having the greatest longevity from day to day. Do I really want to sacrifice some of the battery to this? I’m told the technology is pretty low-power and the key to the success of this project is it’s only using a small part of it. Tiny messages get beaconed out and the phone that is listening has a hardware filter so it only wakes the phone in the background if a beacon with the matching ID comes in.

Plus, it’s Bluetooth Low Energy, so the clue is in the name.

Phase 1 is coming soon, as soon as next month, with Phase 2 due in the months that follow.

There is no unhackable system and there are other issues that need to be addressed, but my initial response from talking to Google and Apple is that they have unimpeachably good intentions and have gone to exceptional lengths to protect privacy.

That data that’s exchanged is meaningless, unless you happen to be the other phone with the same anonymous identifier beacon, the other half of the pair. The lack of geographical information helps, too.