Although blockchains aim for immutability as their core feature, several instances have exposed the harms with perfect immutability. The permanence of illicit content inserted in Bitcoin poses a challenge to law enforcement agencies like Interpol, and millions of dollars are lost in buggy smart contracts in Ethereum. A line of research then spawned on Redactable blockchains with the aim of solving the problem of redacting illicit contents from both permissioned and permissionless blockchains. However, all the existing proposals follow the build-new-chain approach for redactions, and cannot be integrated with existing systems like Bitcoin and Ethereum. We present Reparo, a generic protocol that acts as a publicly verifiable layer on top of any blockchain to perform repairs, ranging from fixing buggy contracts to removing illicit contents from the chain. Reparo facilitates additional functionalities for blockchains while maintaining the same provable security guarantee; thus, Reparo can be integrated with existing blockchains and start performing repairs on the pre-existent data. Any system user may propose a repair and a deliberation process ensues resulting in a decision that complies with the repair policy of the chain and is publicly verifiable. Our Reparo layer can be easily tailored to different consensus requirements, does not require heavy cryptographic machinery and can, therefore, be efficiently instantiated in any permission-ed or -less setting. We demonstrate it by giving efficient instantiations of Reparo on top of Ethereum (with PoS and PoW), Bitcoin, and Cardano. Moreover, we evaluate Reparo with Ethereum mainnet and show that the cost of fixing several prominent smart contract bugs is almost negligible. For instance, the cost of repairing the prominent Parity Multisig wallet bug with Reparo is as low as 0.000000018% of the Ethers that can be retrieved after the fix.
翻译:虽然块链的核心特征是:不易移动,但有几个实例暴露了这些弊端。 Bitcoin 中非法内容的永久性对国际刑警组织等执法机构提出了挑战,在Etheum 的错误智能合同中损失了数百万美元。在Redactical 块链上产生的一行研究,目的是解决经许可和无许可的块链中的非法内容的变异性问题。然而,所有现有提案都遵循了对变异行动的建设-新链方法,无法与Bitcoin和Eieloum等现有系统融合。我们介绍Reparo,这是一个通用协议,在任何块链的顶端上作为可公开核查的一层,从修复错误合同到从链中清除非法内容。Reparo在维持同样的可变安全保证的同时为链增加了额外的功能;因此,Reparo可以与现有的块链集成一体,开始对预存在的数据进行修复。任何系统用户都可以提出一个修复和评议过程,而我们可以用一个成本来完成一个决定,从而遵守Ermal-roral的快速的修复,因此, 需要更精确的升级的升级和升级的升级。我们的任何快速的快速的系统, 需要可以公开的升级的升级的升级和升级的升级的升级的升级, 。我们的任何和升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级的升级和升级。