Georgia Avarikioti, Lukas K ̈appeli, Yuyi Wang, and Roger Wattenhofer (ETH Zurich)
Extension to Garay et al.
(Abstract) We prove Bitcoin is secure under temporary dishonest majority. We assume the adversary can corrupt a specific fraction of parties and also introduce crash failures, i.e., some honest participants are offline during the execution of the protocol. We demand a majority of honest on-line participants on expectation. We explore three different models and present the requirements for proving Bitcoin’s security in all of them. We first examine a synchronous model, then extend to a bounded delay model and last we consider a synchronous model that allows message losses.
Prove that Nakamoto’s protocol achieves, under suitable conditions, consistency and liveness in bounded-delay networks with adaptive (as opposed to predetermined) dynamic participation assuming, as in previous works, that the majority of the computational power favors the honest parties.