Better Safe than Sorry: Recovering after Adversarial Majority

The security of blockchain protocols is a combination of two properties: safety and liveness. It is well known that no blockchain protocol can provide both to sleepy (intermittently online) clients under adversarial majority. However, safety is more critical in that a single safety violation can cau...

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Bibliographic Details
Main Authors Sridhar, Srivatsan, Zindros, Dionysis, Tse, David
Format Journal Article
LanguageEnglish
Published 10.10.2023
Subjects
Computer Science - Cryptography and Security
Computer Science - Distributed, Parallel, and Cluster Computing
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Summary:The security of blockchain protocols is a combination of two properties: safety and liveness. It is well known that no blockchain protocol can provide both to sleepy (intermittently online) clients under adversarial majority. However, safety is more critical in that a single safety violation can cause users to lose money. At the same time, liveness must not be lost forever. We show that, in a synchronous network, it is possible to maintain safety for all clients even during adversarial majority, and recover liveness after honest majority is restored. Our solution takes the form of a recovery gadget that can be applied to any protocol with certificates (such as HotStuff, Streamlet, Tendermint, and their variants).
DOI:10.48550/arxiv.2310.06338