区块链的稳定性：去杠杆螺旋和稳定币攻击
(In)Stability for the Blockchain: Deleveraging Spirals and Stablecoin Attacks
摘要：
我们开发了一个稳定资产模型，包括由加密货币支持的非托管稳定币。这种稳定币是在公共区块链环境中引导价格稳定的流行方法。我们得出了关于稳定币市场的动态和流动性的基本结果，证明了这些市场面临着去杠杆化的反馈效应，这些反馈效应会导致危机期间的流动性不足并加剧抵押品的缩减，并描述了特定条件下系统的稳定动态。这种“去杠杆螺旋”的可能性最早是在2019年我们的论文最初发布时预测的，后来在2020年戴的“黑色星期四”危机期间直接观察到。根据这些见解，我们建议设计改进，旨在提高长期稳定性。我们还介绍了新的攻击，利用围绕稳定币清算的类似仲裁的机会。使用我们的模型，我们证明了这些可以盈利。这些攻击可能会导致“稳定”资产的波动，并对矿工造成不正当的激励，对区块链共识构成风险。类似攻击的另一种形式也发生在黑色星期四期间，采取操纵会员池的形式，以接近零的价格清除Dai的清算拍卖，耗资800万美元。
英文摘要：
We develop a model of stable assets, including non-custodial stablecoins backed by cryptocurrencies. Such stablecoins are popular methods for bootstrapping price stability within public blockchain settings. We derive fundamental results about dynamics and liquidity in stablecoin markets, demonstrate that these markets face deleveraging feedback effects that cause illiquidity during crises and exacerbate collateral drawdown, and characterize stable dynamics of the system under particular conditions. The possibility of such `deleveraging spirals' was first predicted in the initial release of our paper in 2019 and later directly observed during the `Black Thursday' crisis in Dai in 2020. From these insights, we suggest design improvements that aim to improve long-term stability. We also introduce new attacks that exploit arbitrage-like opportunities around stablecoin liquidations. Using our model, we demonstrate that these can be profitable. These attacks may induce volatility in the `stable' asset and cause perverse incentives for miners, posing risks to blockchain consensus. A variant of such attacks also later occurred during Black Thursday, taking the form of mempool manipulation to clear Dai liquidation auctions at near zero prices, costing $8m.
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。
