闪电网络中（非）可退还费用的博弈论分析
Game-Theoretic Analysis of (Non-)Refundable Fees in the Lightning Network
AI总结：
针对闪电网络中支付失败转发节点无补偿、探测攻击无成本的问题，提出不可退还部分费用的博弈模型，可提升支付成功率、降低路由费并增加攻击成本，还给出哈希时间锁定合约的适配修改方案。
摘要：
在支付通道网络（PCNs）中，在发送方和接收方之间转发支付的节点若支付成功则可获得少量费用，该费用是对其临时为支付投入资金的补偿。然而，支付可能因资金不足或攻击而失败，且往往会经历长达数天的显著延迟，导致节点无法获得补偿。此外，攻击者可以故意造成支付失败，例如推断私人信息（如通道余额），且无需支付任何费用成本。\n本文中，我们首先使用扩展式博弈对导致理性中间节点拒绝（或同意）转发支付的条件进行形式化刻画。中间节点是否转发的决策取决于失败概率，它们会根据过往经验对该概率进行估算。随后，我们提出并分析了一种替代性费用模型，该模型允许发送方确定一定比例的费用，并以不可退还的方式支付给中间节点。理性的发送方会选择合适的费用比例，使得中间节点转发支付的效用超过不转发的效用。\n我们基于真实世界的闪电网络快照开展的模拟研究证实，若所有节点均理性行事，我们提出的新机制可将支付成功概率提高12%，并将发送方的路由费用降低约6%。此外，此前无需成本的探测攻击现在要求攻击者每推断100万聪（satoshis）就需要支付1500聪。最后，我们提出了对哈希时间锁定合约（Hash Time Locked Contract）的修改方案，以实现不可退还费用的安全支付。
英文摘要：
In PCNs, nodes that forward payments between a source and a receiver are paid a small fee if the payment is successful. The fee is a compensation for temporarily committing funds to the payment. However, payments may fail due to insufficient funds or attacks, often after considerable delays of up to several days, leaving a node without compensation. Furthermore, attackers can intentionally cause failed payments, e.g., to infer private information (like channel balances), without any cost in fees. In this paper, we first use extensive form games to formally characterize the conditions that lead to rational intermediaries refusing (or agreeing) to forward payments. A decision made by an intermediary to forward or not depends on the probability of failure, which they approximate based on past experience. We then propose and analyze an alternative fee model that allows the sender to determine and pay a fraction of the fee to intermediaries in a non refundable manner. A rational sender chooses the fraction such that the intermediaries' utility for forwarding the payment exceeds their utility for not forwarding. Our simulation study, based on real world Lightning snapshots, confirms that our novel mechanism can increase the probability of successful payments by 12 percent and decrease routing fees for senders by about 6 percent if all nodes behave rationally. Furthermore, previously cost free probing attacks now require that the attacker pays 1500 satoshis for every 1 million satoshis inferred. Finally, we propose a modification to the Hash Time Locked Contract to enable secure payments of the non refundable fees.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
