## Practical, scalable algorithms for Byzantine agreement

Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/17495

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Title

Practical, scalable algorithms for Byzantine agreement

Author(s)

Oluwasanmi, Olumuyiwa

Advisor(s)

Saia, Jared

Committee Member(s)

Bridges, Patrick

Moore, Cristopher

Valerie, King

Moore, Cristopher

Valerie, King

Department

University of New Mexico. Dept. of Computer Science

LC Subject(s)

Computer networks--Scalability.

Fault-tolerant computing.

Computer algorithms.

Fault-tolerant computing.

Computer algorithms.

Degree Level

Doctoral

Abstract

With the growth of the Internet, there has been a push toward designing reliable algorithms that scale effectively in terms of latency, bandwidth and other computational resources. Scalability has been a serious problem especially with peer-to-peer (p2p) networks which may have sizes of more than a million nodes.
An important problem in designing reliable algorithms is Byzantine agreement. For reasons of scalability, message complexity is a critical resource for this problem. Unfortunately, previous solutions to Byzantine agreement require each processor to send $O(n)$ messages, where $n$ is the total number of processors in the network.
In this dissertation, we show that the Byzantine agreement problem can be solved with significantly less that a linear number of messages both in theory and in practice. We implement and test algorithms that solve the classical problem with each processor sending only $\tilde{O}(\sqrt{n})$ messages.
Further, we consider the problem in the case where we assume the existence of a random beacon: a global source of random bits. We show that with this assumption, the required number of messages drops to $O(\log n)$, with small hidden constants.
Our algorithms are Monte Carlo and succeed with high probability, that is probability $1-o(n^k)$ for some positive constant $k$.
Our empirical results suggest that our algorithms may outperform classical solutions to Byzantine agreement for network of size larger than 30,000 nodes.

Date

December 2011

Subject(s)

Byzantine Agreement

Fault-Tolerant

Fault-Tolerance

Randomized Algorithm

Monte Carlo

Random Beacon

Distributed Algorithm

Consensus

Byzantine

Fault-Tolerant

Fault-Tolerance

Randomized Algorithm

Monte Carlo

Random Beacon

Distributed Algorithm

Consensus

Byzantine

##### Collections

- Computer Science [56]