On the robustness of Lightning Network in Bitcoin

An off-chain transaction protocol called Lightning Network was recently introduced to enable low-fee and micropayment transactions on the top of the Bitcoin network. This technology has the potential to solve the inherent scalability issue of the Bitcoin system, but is still questionable whether the proposed system is highly secure and robust against various cyberattacks. In this paper, we analyzed the network characteristics of the Lightning Network mainnet which was launched on March 15, 2018 and found that the Lightning Network topology shows strong scale-free network characteristics. This implies that Lightning Network can be vulnerable to DDoS attacks targeting some specific nodes in the network because there are a few highly connected “hub” nodes in a scale-free network. We experimentally analyze the robustness of Lightning Network via the simulation of network attack model. Our simulation results demonstrate that the connectivity of the existing Lightning Network cannot be maintained sufficiently against target attacks that repeatedly destroy a few nodes with high centrality.