I'm implementing a distributed system using Practical Byzantine Fault Tolerance. This method entrusts a committee to vote for each commit. However, if they are all crashed or under DDoS attack the entire network shall breakdown. I'm curious if there's a way to change the entire committee. This is not the same as a view change because view change only replaces faulty nodes, while this requires all committee members to be replaced, thus forming a dynamic committee.
You cannot change the network members in PBFT because it requires identities of all members to be established in prior before starting the network. This is called static network or closed network. And PBFT can tolerate upto f Byzantine faulty nodes when you have 3f+1 node in total. So if you want to overcome the situation you mentioned (all nodes crashed), you have to consider entire new consensus algorithm unlike PBFT.