Gorilla: Safe Permissionless Byzantine Consensus

Authors Youer Pu, Ali Farahbakhsh, Lorenzo Alvisi, Ittay Eyal

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Youer Pu
  • Cornell University, Ithaca, NY, USA
Ali Farahbakhsh
  • Cornell University, Ithaca, NY, USA
Lorenzo Alvisi
  • Cornell University, Ithaca, NY, USA
Ittay Eyal
  • Technion, Haifa, Israel


We thank Alexandra Silva and Dexter Kozen for useful discussions about proving probabilistic termination.

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Youer Pu, Ali Farahbakhsh, Lorenzo Alvisi, and Ittay Eyal. Gorilla: Safe Permissionless Byzantine Consensus. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 31:1-31:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


Nakamoto’s consensus protocol works in a permissionless model and tolerates Byzantine failures, but only offers probabilistic agreement. Recently, the Sandglass protocol has shown such weaker guarantees are not a necessary consequence of a permissionless model; yet, Sandglass only tolerates benign failures, and operates in an unconventional partially synchronous model. We present Gorilla Sandglass, the first Byzantine tolerant consensus protocol to guarantee, in the same synchronous model adopted by Nakamoto, deterministic agreement and termination with probability 1 in a permissionless setting. We prove the correctness of Gorilla by mapping executions that would violate agreement or termination in Gorilla to executions in Sandglass, where we know such violations are impossible. Establishing termination proves particularly interesting, as the mapping requires reasoning about infinite executions and their probabilities.

Subject Classification

ACM Subject Classification
  • Computer systems organization → Dependable and fault-tolerant systems and networks
  • Consensus
  • Permissionless
  • Blockchains
  • Byzantine fault tolerance
  • Deterministic Safety


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