Recent multi-agent systems are characterized by decentralized control, autonomy and local views. The application of multi-agent systems on open environment such as internet creates new challenges especially with respect to security issues such as authentication, authorization and privacy. The characteristics of multiagent systems introduce vulnerabilities and threats to secured communication. One practical way to minimize the threats is to evaluate the trust and reputation of the agents. But trust is not enough for secure communication. Many trust/reputation models have given solutions, but they fail to properly evaluate trust when malicious agents start to behave in an unpredictable way and also they fail to address the problem of secure communication between agents. In this paper a secure communication for reputation system in multiagent system is proposed. It provides a flexible way to present differentiated trust and combine different aspects of trust that can meet agent's different needs. And also it allows secure file delivery among agents. The idea of using cryptographic protocols MD5 and DES effectively encrypt the file without any overhead to the network.

Multiagent system Security Cryptography Trust Reputation