Availability for DHT-based overlay networks with unidirectional routing

Abstract

Distributed Hash Tables (DHTs) provide a formally defined structure for overlay networks to store and retrieve content. However, handling malicious nodes which intentionally disrupt the DHT's functionality is still a research challenge. One particular problem - which is the scope of this paper - is providing availability of the DHT's lookup service in the presence of attackers. We focus on DHTs with unidirectional routing and present concrete algorithms to extend one particular such DHT, namely Chord. Our extensions provide independent multipath routing and enable routing to replica roots despite attackers on the regular routing path. In addition, we investigate algorithms to detect adversary nodes which employ node-ID suppression attacks during routing. We demonstrate how these techniques can be combined to increase lookup success in a network under attack by deriving analytical bounds for our proposed extensions and simulating how our algorithms come close to these bounds. © 2008 Springer-Verlag Berlin Heidelberg.