Table 1: Function of messages and the time when they are sent.

Message typeTime when message is sent

CS (Cluster Separator) messageAt the beginning of step 1
Determines a cluster border

CR (Cluster Response) messageUpon receiving a CS message
Request to join a cluster

FCS (Final Cluster Separator) messageAt the beginning of the step 2
Merges a CS node into a cluster

Solicitation messageWhen a victim does not receive a FCS message from its CS node
Acquire witnesses to prove its legitimacy

Solicitation response messageWhen a node receives a Solicitation message and holds any evidence
Proves a victim’s legitimacy

Attacker report messageWhen a victim confirms misbehavior of a CS node
Excludes a CS node from members