If I understand you correctly, this is exactly the procedure that Stanford's CovidWatch is implementing. https://www.covid-watch.org/article#contactTracing htt

If I understand you correctly, this is exactly the procedure that Stanford's CovidWatch is implementing. https://www.covid-watch.org/article#contactTracing https://www.covid-watch.org/article#contactTracing They are pushing for a standard protocol that incorporates this mechanism. It may or may not be compatible with the joint effort of Google and Apple, and with Singapore's under-development BlueTrace standard. https://en.m.wikipedia.org/wiki/BlueTrace https://en.m.wikipedia.org/wiki/BlueTrace