Towards Sybil-resilient P2P Networks

Recently, Sybil attack has become one of the most visible security problems in the peer to peer networks where it is not possible to depend on trusted authorities for admission control or maintenance. In such networks or in any open distributed systems, an adversary creates many fake identities in order to increase its influence and deny service to honest participants. Defending against this attack is challenging because creating many fake identities is cheap. In this project, our contributions are two-fold. Our main contribution is a sybil-resistant Distributed Hash Table, where sybil nodes can join, but the routing algorithm for an honest node can effectively bypass the sybil identities. Our method assumes that each node have direct knowledge about their neighbors and have established social trust relationships with them. With this knowledge in hand, our methods uses gossip algorithms to assign IDs to the nodes in a distributed manner. The IDs are linear binary codes (for instance, extended Golay codes) which constitutes the XOR based routing mechanism for the distributed hash table “Plexus.” Existing sybil-proof DHTs either depend on explicit ID generation, or routings take grossly suboptimal paths, or the finger table size becomes larger. However, our scheme successfully manages all of these parameters and as a added benefit of Plexus, offers disjoint diversified optimal routes and mirroring capability for fault tolerance. Based on these findings, we have also presented a layered architecture of a distributed admission control and maintenance scheme for a peer to peer network, which is our second contribution.