标题： 在信誉加权贷款网络中抑制离线支付中的双花问题 显示英文标题

标题： Taming Double-Spending in Offline Payments with Reputation-Weighted Loan Networks

摘要： 区块链解决方案通常假设同步网络以确保一致性并达成共识。 相反，离线交易系统旨在使用户能够在不假设有限通信延迟的情况下就交易达成一致并执行。 大多数现有的离线支付方案依赖于可信的硬件钱包，这些钱包被假定为安全且防篡改。 虽然这项工作引入了Overdraft，一种新颖的离线支付系统，它将依赖从硬件转移到用户自身。 Overdraft允许潜在的支付接收者评估被支付的可能性，从而使他们能够有信心地接受交易或拒绝交易。 Overdraft通过维护一个由在线声誉加权的贷款网络来实现这一点。 这个贷款网络包含时间限制的协议，其中用户承诺在必要时覆盖另一用户的支付。 例如，当付款人当时资金不足时。 离线用户依靠最后一次已知的贷款网络视图——他们在上次在线时访问的视图——来决定是否参与离线交易。 此视图用于估计最终支付的概率，可能使用多个贷款。 再次上线后，用户会将他们的交易提交到区块链上，任何冲突都会被确定性地解决。 Overdraft包含了对用户的激励措施，并设计为能够抵御Sybil攻击。 作为概念验证，我们实现了 Overdraft作为Ethereum Solidity智能合约，并将其部署在Sepolia测试网上以评估其性能。 显示英文摘要

摘要： Blockchain solutions typically assume a synchronous network to ensure consistency and achieve consensus. In contrast, offline transaction systems aim to enable users to agree on and execute transactions without assuming bounded communication delays when interacting with the blockchain. Most existing offline payment schemes depend on trusted hardware wallets that are assumed to be secure and tamper-proof. While this work introduces Overdraft, a novel offline payment system that shifts the reliance from hardware to users themselves. Overdraft allows potential payment receivers to assess the likelihood of being paid, allowing them to accept transactions with confidence or deny them. Overdraft achieves this by maintaining a loan network that is weighted by online reputation. This loan network contains time-limited agreements where users pledge to cover another user's payment if necessary. For example, when a payer lacks sufficient funds at the moment of commitment. Offline users rely on the last known view of the loan network -- which they had access to when last online -- to determine whether to participate in an offline transaction. This view is used to estimate the probability of eventual payment, possibly using multiple loans. Once online again, users commit their transactions to the blockchain with any conflicts being resolved deterministically. Overdraft incorporates incentives for users and is designed to be resilient against Sybil attacks. As a proof of concept, we implemented Overdraft as an Ethereum Solidity smart contract and deployed it on the Sepolia testnet to evaluate its performance.