In this paper, we propose how to parameterize and maintain a reputation system that, based on the current network conditions, supports the selection of the optimal end-to-end communication path for VoIP communication in a P2P context. Each node’s reputation is formed based on three factors: (1) performance reputation (own experience from passive measures of the network conditions); (2) security reputation; and (3) information reputation consisting of recommendations from other nodes. Reputation data is periodically updated from continuous monitoring of path quality and security and also from information exchange between the nodes. When network conditions deteriorate, the reputation system enables switching, if possible, to another available path for furthercommunication. The proposed reputation system is a component of the SecMon system, which is intended especially for VoIP service over P2P networks. SecMon features lightweight QoS parameter monitoring, authentication and data integrity services. The exchange of monitoring information represents a low-bandwidth consumption solution that is transparent to the users and possesses a self-organizing capability. The above-mentioned exchange features are accomplished by utilizing two information hiding techniques: digital audio watermarking and network steganography. These techniques are used to create covert channels that serve as transport channels for lightweight QoS measurement results. Moreover, in this paper, we present results of the simulations that were performed to investigate how the proposed reputation system is performing for a simple twopath case scenario. Additionally, we show how different network conditions like delays and packet losses affect the proposed reputation system and how they are modeled with utility functions. Results of the simulations also illustrate the approaches to thresholds that trigger path changes.

Pappret utvecklar ett "ryktessystem" (reputation system) som kombinerar uppmätta kommunikationskvalitets- och säkerhetsparametrar som unterlag för vägvalet i ett Peer-to-Peer (P2P) nätverk.