Improvement and partial simulation of King & Saia’s expected-polynomial-time Byzantine agreement algorithm




Kimmett, Ben

Journal Title

Journal ISSN

Volume Title



We present a partial implementation of King and Saia 2016’s expected polyno- mial time byzantine agreement algorithm, which which greatly speeds up Bracha’s Byzantine agreement algorithm by introducing a shared coin flip subroutine and a method for detecting adversarially controlled nodes. In addition to implementing the King-Saia algorithm, we detail a new version of the “blackboard” abstraction used to implement the shared coin flip, which improves the subroutine’s resilience from t < n/4 to t < n/3 and leads to an improvement of the resilience of the King-Saia Byzantine agreement algorithm overall. We test the King-Saia algorithm, and detail a series of adversarial attacks against it; we also create a Monte Carlo simulation to further test one particular attack’s level of success at biasing the shared coin flip



byzantine agreement, interactive consistency, Bracha, x-sync, shared coin flip, decision, adversary, asynchronous, reliable broadcast, validation, blackboard, Monte Carlo simulation, polynomial time, King-Saia, King, Saia, resilience, improved resilience, Global-Coin