International Association for Cryptologic Research

International Association
for Cryptologic Research


Early Stopping for Any Number of Corruptions

Julian Loss , CISPA Helmholtz Center for Information Security
Jesper Buus Nielsen , Aarhus University
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Presentation: Slides
Conference: EUROCRYPT 2024
Abstract: Minimizing the round complexity of byzantine broadcast is a fundamental question in distributed computing and cryptography. In this work, we present the first \emph{early stopping} byzantine broadcast protocol that tolerates up to $t=n-1$ malicious corruptions and terminates in $\cO(\min\{f^2,t+1\})$ rounds for any execution with $f\leq t$ \emph{actual corruptions}. Our protocol is deterministic, adaptively secure, and works assuming a plain public key infrastructure. Prior early-stopping protocols all either require honest majority or tolerate only up to $t=(1-\epsilon)n$ malicious corruptions while requiring either trusted setup or strong number theoretic hardness assumptions. As our key contribution, we show a novel tool called a \emph{polarizer} that allows us to transfer certificate-based strategies from the honest majority setting to settings with a dishonest majority.
  title={Early Stopping for Any Number of Corruptions},
  author={Julian Loss and Jesper Buus Nielsen},