A team of MIT researchers is working on a system through which people's phones would send out a constant stream of Bluetooth "chirps" that would then be picked up and stored by other people's phones. Somebody who tests positive for coronavirus could then upload his or her chirps to a database that others could then check to see if they were close enough to that person to warrant their own trip to testing site or to self quarantine.
Bluetooth is designed for only short distances, such as, oh, six feet.
"I keep track of what I’ve broadcasted, and you keep track of what you’ve heard, and this will allow us to tell if someone was in close proximity to an infected person," says Ron Rivest, MIT Institute Professor and principal investigator of the project. “But for these broadcasts, we’re using cryptographic techniques to generate random, rotating numbers that are not just anonymous, but pseudonymous, constantly changing their 'ID,' and that can’t be traced back to an individual."
And, yes, one of the things they figure out how to do was to have Android and Apple phones communicate their chirps.
Rivest is one of the RSA encryption algorithm.
Last week, Gov. Baker announced a more traditional method for such "contact tracing" - a system in which people who test positive are called to try to track down anybody they might have come into contact with so that they can then be called to be, at the least, urged to self quarantine for two weeks.