ReDS: A Framework for Reputation-Enhanced DHTs

TL;DR

ReDS is a framework that enhances the reliability of DHT lookups by tracking node reputation, significantly improving success rates even under malicious attacks and network churn.

Contribution

This paper introduces ReDS, a novel reputation-based framework applicable to various redundant DHTs, improving lookup robustness without relying on reputation score sharing.

Findings

ReDS improves lookup success rates by over 80%.

ReDS is effective against strategic attackers and node churn.

ReDS can be applied to multiple DHT systems like Halo and Kad.

Abstract

Distributed Hash Tables (DHTs) such as Chord and Kademlia offer an efficient solution for locating resources in peer-to-peer networks. Unfortunately, malicious nodes along a lookup path can easily subvert such queries. Several systems, including Halo (based on Chord) and Kad (based on Kademlia), mitigate such attacks by using a combination of redundancy and diversity in the paths taken by redundant lookup queries. Much greater assurance can be provided, however. We describe Reputation for Directory Services (ReDS), a framework for enhancing lookups in redundant DHTs by tracking how well other nodes service lookup requests. We describe how the ReDS technique can be applied to virtually any redundant DHT including Halo and Kad. We also study the collaborative identification and removal of bad lookup paths in a way that does not rely on the sharing of reputation scores --- we show that such sharing is vulnerable to attacks that make it unsuitable for most applications of ReDS. Through extensive simulations we demonstrate that ReDS improves lookup success rates for Halo and Kad by 80% or more over a wide range of conditions, even against strategic attackers attempting to game their reputation scores and in the presence of node churn.