Flipping coins in many pockets (byzantine agreement on uniformly random values)

Andrei Z. Broder, Danny Dolev

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

It was recently shown by Michael Rabin that a sequence of random 0-1 values, prepared and distributed by a trusted "dealer,"can be used to achieve Byzantine agreement in constant expected time in a network of processors. A natural question is whether it is possible to generate these values uniformly at random within the network. In this paper we present a cryptography based protocol for agreement on a 0-1 random value, if less than half of the processors are faulty. In fact the protocol allows uniform sampling from any finite set, and thus solves the problem of choosing a network leader uniformly at random. The protocol is usable both when all the communication is via "broadcast,"in which case it needs three rounds of information exchange, and when each pair of processors communicate on a private line, in which case it, needs 3t + 3 rounds, where t is the number of faulty processors. The protocol remains valid even if passive eavesdropping is allowed. On the other hand we show that no (probabilistic) protocol can achieve agreement on a fair coin in fewer phases then necessary for Byzantine agreement, and hence the "pre-dealt"nature of the random sequence required for Rabin's algorithm is crucial.

Original languageEnglish
Title of host publication25th Annual Symposium on Foundations of Computer Science, FOCS 1984
PublisherIEEE Computer Society
Pages157-170
Number of pages14
ISBN (Electronic)081860591X
StatePublished - 1984
Event25th Annual Symposium on Foundations of Computer Science, FOCS 1984 - Singer Island, United States
Duration: 24 Oct 198426 Oct 1984

Publication series

NameProceedings - Annual IEEE Symposium on Foundations of Computer Science, FOCS
Volume1984-October
ISSN (Print)0272-5428

Conference

Conference25th Annual Symposium on Foundations of Computer Science, FOCS 1984
Country/TerritoryUnited States
CitySinger Island
Period24/10/8426/10/84

Bibliographical note

Publisher Copyright:
© 1984 IEEE.

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