CougaR

Abstract

Despite their development for over a decade, a key problem block-chains are still facing is scalability in terms of throughput, typically limited to a few transactions per second. A fundamental factor limiting this metric is the propagation latency of blocks through the underlying peer-to-peer network, which is typically constructed by means of random connectivity. Disseminating blocks fast improves not only the transaction throughput, but also the security of the system as it reduces the probability of forks. In this paper we present CougaR: a simple yet efficient, eclipse-resistant, decentralized protocol that substantially reduces the block dissemination time in blockchain networks. CougaR's key advantages stem from its link selection policy, which combines a network latency criterion with randomness to offer fast and reliable block dissemination to the entire network. Moreover, CougaR is eclipse-resistant by design, as nodes are protected from having all their links directly or indirectly imposed on them by others, which is the typical vulnerability exploited to deploy eclipse attacks. We rigorously evaluate CougaR by an extensive set of experiments, both against a wide spectrum of parameter settings, and in comparison to the current state of the art.