Most permissionless blockchain networks run on peer-to-peer (P2P) networks, which offer flexibility and decentralization at the expense of performance (e.g., network latency). Historically, this tradeoff has not been a bottleneck for most blockchains. However, an emerging host of blockchain-based applications (e.g., decentralized finance) are increasingly sensitive to latency; users who can reduce their network latency relative to other users can accrue (sometimes significant) financial gains. In this work, we initiate the study of strategic latency reduction in blockchain P2P networks. We first define two classes of latency that are of interest in blockchain applications. We then show empirically that a strategic agent who controls only their local peering decisions can manipulate both types of latency, achieving 60\% of the global latency gains provided by the centralized, paid service bloXroute, or, in targeted scenarios, comparable gains. Finally, we show that our results are not due to the poor design of existing P2P networks. Under a simple network model, we theoretically prove that an adversary can always manipulate the P2P network's latency to their advantage, provided the network experiences sufficient peer churn and transaction activity.

翻译：绝大多数无许可区块链网络运行于点对点（P2P）网络之上，这种网络在提供灵活性和去中心化的同时，也牺牲了性能（如网络延迟）。历史上，这一权衡并未成为大多数区块链的瓶颈。然而，新兴的区块链应用（如去中心化金融）对延迟愈发敏感；能够相对其他用户降低自身网络延迟的用户，可以获得（有时是显著的）经济收益。本研究首次对区块链P2P网络中的策略性延迟降低问题展开探讨。我们首先定义了区块链应用中两类值得关注的延迟类型。随后通过实证表明，仅通过控制本地对等连接决策的策略性代理，即可操纵上述两类延迟，实现由中心化付费服务bloXroute提供的全局延迟增益的60%，或在特定场景下达到与之相当的性能。最后，我们证明这些结果并非源于现有P2P网络的糟糕设计。在简单网络模型下，我们理论证明：只要网络存在足够的节点轮替与交易活动，攻击者总能操纵P2P网络延迟以使其自身获益。