An Improved Approximate Consensus Algorithm in the Presence of Mobile Faults

  • Lewis TsengEmail author
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10616)


This paper explores the problem of reaching approximate consensus in synchronous point-to-point networks, where each pair of nodes is able to communicate with each other directly and reliably. We consider the mobile Byzantine fault model proposed by Garay ’94 – in the model, an omniscient adversary can corrupt up to f nodes in each round, and at the beginning of each round, faults may “move” in the system (i.e., different sets of nodes may become faulty in different rounds). Recent work by Bonomi et al. ’16 proposed a simple iterative approximate consensus algorithm which requires at least \(4f+1\) nodes. This paper proposes a novel technique of using “confession” (a mechanism to allow other nodes to ignore past behavior) and a variant of reliable broadcast to improve the fault-tolerance level. In particular, we present an approximate consensus algorithm that requires only \(\lceil 7f/2\rceil + 1\) nodes, an \(\lfloor f/2 \rfloor \) improvement over the state-of-the-art algorithms. Moreover, we also show that the proposed algorithm is optimal within a family of round-based algorithms.


Byzantine mobile faults Iterative algorithms Approximate consensus 


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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Computer ScienceBoston CollegeBostonUSA

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