Proactive Secret Sharing in Dynamic Environments

Andrew Low, Deepak Krishna, Fan Zhang, Lun Wang, Yupeng Zhang, 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.

Advisor: Dawn Song


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