Your use of the word partial could lead to confusion. The Diagnosis Keys are a subset of the Daily Tracing Keys for the days youre contagious. You then upload these Daily Tracing Keys and associated day numbers. Also you are incorrect about the involvement of a timestamp. The protocol uses DayNumbers to track the specific day a Daily Tracing Number was used.

In terms of privacy, small-scale adversaries can deanonymize infected users that have uploaded their [keys by keeping logs] of and limiting who they have come in close contact with.

On a large-scale, adversaries in control of large Bluetooth receiver networks (such as cities performing traffic analysis) can now track the movements of individual infected users over the course of a day. One could argue that this is already being done to track anyone with bluetooth enabled.

In addition, the process of uploading to the backend server could alert adversaries monitoring your network that you (the device using your IP address, uploading to the server IP address) have tested positive for the virus.

I recommend that you look at other contact tracing protocols that circumvent some of these issues by decrease or eliminating the linkability of identifiers, allowing users to censor records uploaded, and encourge the use of network-anonymization.

*Edit Spelling - Source: https://covid19-static.cdn-apple.com/applications/covid19/cu...