Snippet: Privacy and How the Apple & Google’s System Might Work ☍

Matthew Panzarino for TechCrunch:

The system works by assigning a random, rotating identifier to a person’s phone and transmitting it via Bluetooth to nearby devices. That identifier, which rotates every 15 minutes and contains no personally identifiable information, will pass through a simple relay server that can be run by health organizations worldwide.

Even then, the list of identifiers you’ve been in contact with doesn’t leave your phone unless you choose to share it. Users that test positive will not be identified to other users, Apple or Google. Google and Apple can disable the broadcast system entirely when it is no longer needed.

All identification of matches is done on your device, allowing you to see — within a 14-day window — whether your device has been near the device of a person who has self-identified as having tested positive for COVID-19. […]

A quick example of how a system like this might work.

1. Two people happen to be near each other for a period of time, let’s say 10 minutes. Their phones exchange the anonymous identifiers (which change every 15 minutes).
2. Later on, one of those people is diagnosed with COVID-19 and enters it into the system via a Public Health Authority app that has integrated the API.
3. With an additional consent, the diagnosed user allows his anonymous identifiers for the last 14 days to be transmitted to the system.
4. The person they came into contact with has a Public Health app on their phone that downloads the broadcast keys of positive tests and alerts them to a match.
5. The app gives them more information on how to proceed from there.