A mobile ad hoc network (MANET) is a self-organized wireless network where mobile nodes can communicate with each other without the use of any existing network infrastructure or centralized administration. Trust establishment and management are essential for any security framework of MANETs. However, traditional solutions to key management
through accessing trusted authorities or centralized servers are infeasible for MANETs due to the absence of infrastructure, frequent mobility, and wireless link instability. In most ad hoc network applications, the number of nodes is not fixed and the network should be flexible to add new members according to different situations. In this paper, a verifiable new member joining in threshold key management scheme for MANETs is presented. The proposed scheme is implemented using elliptic curve dlog-based cryptosystem. In this scheme, the new member broadcasts a joining request and if at least k neighbors trust the new member, they cooperate to issue the new member the keying materials required to join the network. The advantages of the proposed scheme are justified through extensive simulations.