Super Peer should provide proof that specified client has joined him
Currently, any super peer can announce that a certain other node has joined him as a client. A harmful super peer could thus intentionally spread false routing information to other super peers. To prevent this, the super peer should provide proof, which shows that the client has joined him as a client.
Since a client can change its super peer over time, multiple valid proofs can exist that client. To allow the system to identify the current super peer, proofs must be chronologically sortable.