A Simple and Efficient Randomized Byzantine Agreement Algorithm

Benny Chor, Brian A. Coan

Research output: Contribution to journalArticlepeer-review


A new randomized Byzantine agreement algorithm is presented. This algorithm operates in a synchronous system of n processors, at most t of which can fail. The algorithm reaches agreement in O(t/log n) expected rounds and O(n2t/log n) expected message bitsindependent of the distribution of processor failures. This performance is further improved to a constant expected number of rounds and O(n2) message bits if the distribution of processor failures is assumed to be uniform. In either event, the algorithm improves on the known lower bound on rounds for deterministic algorithms. Some other advantages of the algorithm are that it requires no cryptographic techniques, that the amount of local computation is small, and that the expectednumber of random bits used per processor is only one. It is argued that in many practical applications of Byzantine agreement, the randomized algorithm of this paper achieves superior performance.

Original languageEnglish
Pages (from-to)531-539
Number of pages9
JournalIEEE Transactions on Software Engineering
Issue number6
StatePublished - Jun 1985
Externally publishedYes


  • Byzantine agreement
  • algorithms
  • fault-tolerance
  • randomized

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