Wouldn't a "find my phone" feature like Apple developed be possible to use in this case? See: https://blog.cryptographyengineering.com/2019/06/05/how-does-appl

Wouldn't a "find my phone" feature like Apple developed be possible to use in this case? See: https://blog.cryptographyengineering.com/2019/06/05/how-does-apple-privately-find-your-offline-devices/ https://blog.cryptographyengineering.com/2019/06/05/how-does... I think that with two tweaks, we could cast a pretty wide net and remain privacy preserving: 1. Phones record a 14 day history of every pseudonym and public key they generate, as well as every pseudonym and public key they observe. Observers (potentially exposed contacts) could encrypt these observations with their own public keys and upload them using the same method Apple uses, I believe. 2. People who test positive can opt in to publishing those pairs publicly, which would allow any device to scan its history for those pairs and determine if its owner has been exposed. Or alternatively, Apple or another company could perform this on a user's behalf using the central database. I think the privacy preserving aspect is dependent on users opting in to sharing information for the past 14 days following a covid-19 test. That would allow the contacts to perform the same "have I seen this device" search locally. Edit: This actually seems a lot like "haveibeenpwned" more-so than anything else. As long as a case's device generated unique IDs continuously, logged them privately and broacasted them to nearby devices, then a potentially exposed contact's device could regularly query a central database for hashed prefixes of IDs they've seen in the past 2 weeks. Any person (case) who tests positive could opt-in to publishing all of the IDs their phone has generated in the past 2 weeks. The contacts could then opt in to publishing the location said contact occurred, and a hash of a geofence could also be logged - allowing contacts who have been exposed to opt in to publishing that someone in a particular vicinity had tested positive and was present at a particular date and time.