Trust But Verify : A Framework for the Trustworthiness of Distributed Systems

Distributed networking technologies have gained popularity as a mechanism for users to share files without the need for centralized servers. A Distributed network provides a scalable and fault-tolerant mechanism to locate nodes anywhere on a network without maintaining a large amount of routing nodes. This can allows for a variety of applications beyond simple sharing of file. This includes multicast systems, and communication systems, and caches of web. We survey security issues that occur in the underlying Distributed routing protocols, along with fairness and trust that occur in file sharing and other Distributed systems. Here we discuss how techniques, ranging from cryptography techniques, to randomize network guessing, can be used to address these problems. Open nature of Distributed systems exposes them to malicious activity. Defining trusty relationships among peers can mitigate attacks of malicious peers. This paper presents distributed algorithms that enable a peer to reason about trustworthiness of other peers based on past interactions. System peers create their own trust network in their proximity by using local information available and do not try to learn global trust information. Two contexts of trust context, service context, and recommendation, these are defined to measure trustworthiness in providing services and giving recommendations. These recommendations are derived based on priority, history, and peer satisfaction. Moreover, nodes trustworthiness and confidence about a recommendation are considered while evaluating recommendations. Effective experiments on a file sharing application show that the proposed model can mitigate attacks on 16 different malicious behavior nodes.