Today, Peer-to-Peer SIP based communication systems have attracted much attention from both the academia and industry. The decentralized nature of P2P might provide the distributed peer-to-peer communication system without help of the traditional SIP server. However, the decentralization features come to the cost of the reduced manageability and create new concerns. Until now, the main focus of research was on the availability of the network and systems, while few attempts are put on protecting privacy. In this chapter, we investigate on P2PSIP security issues and introduce two enhancement solutions: central based security and distributed trust security, both of which have their own advantages and disadvantages. After that, we study appropriate combination of these two approaches to get optimized protection. Our design is independent of the DHT (Distributed Hash Table) overlay technology. We take the Chord overlay as the example, and then, analyze the system in several aspects: security & privacy, number-of the hops, message flows, etc.
The missing piece syndrome in peer-to-peer communication