Andrew Low and Deepak Krishna and Fan Zhang and Lun Wang and Yupeng Zhang and Ari Juels and Dawn Song

EECS Department, University of California, Berkeley

Technical Report No. UCB/EECS-2019-62

May 17, 2019

http://www2.eecs.berkeley.edu/Pubs/TechRpts/2019/EECS-2019-62.pdf

We introduce CHURP (CHUrn-Robust Proactive secret sharing). CHURP enables secure secret sharing in dynamic settings, where the committee of nodes storing a secret changes over time. Designed for blockchains, CHURP has lower communication complexity than previous schemes: O(n) on-chain and O(n^2) off-chain in the optimistic case of no node failures.

CHURP includes several technical innovations: An efficient new proactivization scheme, a technique (using asymmetric bivariate polynomials) for efficiently changing secret-sharing thresholds, and a hedge against setup failures in an efficient polynomial commitment scheme. We report on the functionality and implementation of CHURP, and present performance improvements.

Advisors: Dawn Song

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BibTeX citation:

@mastersthesis{Low:EECS-2019-62,
    Author= {Low, Andrew and Krishna, Deepak and Zhang, Fan and Wang, Lun and Zhang, Yupeng and Juels, Ari and Song, Dawn},
    Title= {Proactive Secret Sharing in Dynamic Environments},
    School= {EECS Department, University of California, Berkeley},
    Year= {2019},
    Month= {May},
    Url= {http://www2.eecs.berkeley.edu/Pubs/TechRpts/2019/EECS-2019-62.html},
    Number= {UCB/EECS-2019-62},
    Abstract= {We introduce CHURP (CHUrn-Robust Proactive secret sharing). CHURP enables secure secret sharing in dynamic settings, where the committee of nodes storing a secret changes over time. Designed for blockchains, CHURP has lower communication complexity than previous schemes: O(n) on-chain and O(n^2) off-chain in the optimistic case of no node failures.

CHURP includes several technical innovations: An efficient new proactivization scheme, a technique (using asymmetric bivariate polynomials) for efficiently changing secret-sharing thresholds, and a hedge against setup failures in an efficient polynomial commitment scheme. We report on the functionality and implementation of CHURP, and present performance improvements.},
}

EndNote citation:

%0 Thesis
%A Low, Andrew 
%A Krishna, Deepak 
%A Zhang, Fan 
%A Wang, Lun 
%A Zhang, Yupeng 
%A Juels, Ari 
%A Song, Dawn 
%T Proactive Secret Sharing in Dynamic Environments
%I EECS Department, University of California, Berkeley
%D 2019
%8 May 17
%@ UCB/EECS-2019-62
%U http://www2.eecs.berkeley.edu/Pubs/TechRpts/2019/EECS-2019-62.html
%F Low:EECS-2019-62