Your suggestions don't seem different from what the spec already describes. Tests are not immediate and the incubation period of the disease dictates that you h

Your suggestions don't seem different from what the spec already describes. Tests are not immediate and the incubation period of the disease dictates that you have to share multiple diagnosis keys (days) of infected persons anyway. You don't have to share timeslots within a day, they can be derived from the daily key. Impersonation risk is unlikely, whatever health authority applies can just invalidate all newly identified keys from generating new contacts, preventing replay attacks derived from known infected with simple and coarse timestamps.