> contact tracing only makes sense when groups of strangers come into close proximity. it doesn't need to track every single person you brush past on the street

> contact tracing only makes sense when groups of strangers come into close proximity. it doesn't need to track every single person you brush past on the street. so for instance, you could just provide "contact tracing" with beacons in stores rather than always-on phone tracing. The part of this comment that actually addresses contact tracing proposes a method (beacons in stores that would have to rely on fixed identifiers, known geolocation, and central storage) that would not only be worse for privacy than what is proposed here, it is also the likely outcome without employing a technique that at least considers privacy concerns. The other paragraphs read like a compilation of Facebook-based science, where not simply factually incorrect, all points made are debatable and by no means as clear as you make it out to be. This is a opt-in API and a technical protocol specification which we can discuss on technical grounds. Nothing proposed and discussed here even affects data leaving the end user device, or your rights for that manner, yet.