For a university project, I have to design a contact tracing protocol. In my approach, a blockchain is used. Every participant has to generate 3 nonces for every contact. They are hashed in multiple ways to guarantee anonymity. Does this approach make sense? Does it guarantee anonymity and integrity?
Here is the sequence diagram, I have in mind. Only Bob's side of the tracing protocol is displayed. h() is a cryptographic hash function. BC is the Blockchain (and therefore public). Alice and Bob should not be able to be linked together unless one reports an infection.