S-Kademlia: a Trust and Reputation Method to Mitigate a Sybil Attack in Kademlia

Peer-to-peer architectures have become very popular in the last years for a variety of services and applications such as collaborative computing, streaming and VoIP applications. The security and integrity of the overlay involved in such networks is a fundamental prerequisite for deploying such a technology. Withstanding multiple false identities in the overlay, also known as a Sybil attack, is one of the main challenges in securing structured peer-to-peer networks. Poisoning routing tables through these identities may make the routing and storage and retrieval processes extremely difficult and time consuming. In this paper we investigate possible countermeasures and propose a novel method for making the routing and the storage and retrieval of resources in a Kademlia network more secure through the use of a combined trust-based algorithm exploiting reputation techniques. Our solution provides a balanced mixing of standard Kademlia algorithms and trust-based algorithms showing promising results in thwarting a Sybil attack in a Kademlia network, in comparison with similar methods as well.