Journal of Cryptology

, Volume 18, Issue 3, pp 191–217 | Cite as

Byzantine Agreement Given Partial Broadcast

  • Jeffrey ConsidineEmail author
  • Matthias FitziEmail author
  • Matthew FranklinEmail author
  • Leonid A. LevinEmail author
  • Ueli MaurerEmail author
  • David MetcalfEmail author


This paper considers unconditionally secure protocols for reliable broadcast among a set of n players, where up to t of the players can be corrupted by a (Byzantine) adversary but the remaining h = n - t players remain honest. In the standard model with a complete, synchronous network of bilateral authenticated communication channels among the players, broadcast is achievable if and only if 2n/h < 3. We show that, by extending this model by the existence of partial broadcast channels among subsets of b players, global broadcast can be achieved if and only if the number h of honest players satisfies 2n/h < b + 1. Achievability is demonstrated by protocols with communication and computation complexities polynomial in the size of the network, i.e., in the number of partial broadcast channels. A respective characterization for the related consensus problem is also given.

Broadcast Byzantine agreement 


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Copyright information

© International Association for Cryptologic Research 2005

Authors and Affiliations

  1. 1.Computer Science Department, Boston University, Boston, MA 02215USA
  2. 2.Department of Computer Science, University of Århus, 8000 Aarhus CDenmark
  3. 3.Department of Computer Science, University of California, Davis, CA 95616USA
  4. 4.Department of Computer Science, ETH Zurich, CH-8092 ZurichSwitzerland

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