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.

最近引入了名为Lightning Network的链下交易协议，以在比特币网络的顶部实现低费用和小额支付交易。这项技术具有解决比特币系统固有的可扩展性问题的潜力，但是对于所提议的系统是否具有高度安全性和强大的抵御各种网络攻击的能力仍存在疑问。

在本文中，我们分析了2018年3月15日启动的Lightning Network主网的网络特性，发现Lightning Network拓扑显示出强大的无标度网络特性。这意味着闪电网络可能会遭受针对网络中某些特定节点的DDoS攻击，因为在无标度网络中有一些高度连接的“集线器”节点。我们通过网络攻击模型的仿真实验分析了闪电网络的鲁棒性。我们的仿真结果表明，现有的闪电网络的连通性无法得到足够的抵抗，以防目标攻击反复摧毁具有高度集中性的几个节点。