Associated data in evidences

[fjarri]

Sometimes we want to prove that the evidence is valid given some well-known data (e.g. the verifying key jointly owned by the group of nodes). Can we do that? ProtocolError will have to have some associated type, and a value of that type will have to be passed to verify.

Do we even need that? Need to see if it comes up in synedrion.

[fjarri]

It does come up in synedrion: in KeyRefresh we need to be sure that the mapping (id -> share change) sent to us contains the correct IDs of participating parties. The list of participants can only be supplied externally when verifying the evidence.