Cryptology ePrint Archive: Report 2018/319

HydRand: Practical Continuous Distributed Randomness

Philipp Schindler and Aljosha Judmayer and Nicholas Stifter and Edgar Weippl

Abstract: A reliable source of randomness is not only an essential building block in various cryptographic, security, and distributed systems protocols, but also plays an integral part in the design of many new blockchain proposals. Consequently, the topic of publicly-verifiable, bias-resistant and unpredictable randomness has recently enjoyed increased attention. In particular random beacon protocols, aimed at continuous operation, can be a vital component for current Proof-of-Stake based distributed ledger proposals. We improve upon previous random beacon approaches with HydRand, a novel distributed protocol based on publicly-verifiable secret sharing (PVSS) to ensure unpredictability, bias-resistance, and public-verifiability of a continuous sequence of random beacon values. Furthermore, HydRand provides guaranteed output delivery of randomness at regular and predictable intervals in the presence of adversarial behavior and does not rely on a trusted dealer for the initial setup. Compared to existing PVSS based approaches that strive to achieve similar properties, our solution improves scalability by lowering the communication complexity from $ \mathcal{O}(n^3) $ to $ \mathcal{O}(n^2) $. Furthermore, we are the first to present a detailed comparison of recently described schemes and protocols that can be used for implementing random beacons.

Category / Keywords: cryptographic protocols / distributed randomness, randomness beacon, Byzantine agreement

Original Publication (with minor differences): to appear in: Proceedings of the 2020 IEEE Symposium on Security and Privacy

Date: received 4 Apr 2018, last revised 30 Jul 2019

Contact author: pschindler at sba-research org

Available format(s): PDF | BibTeX Citation

Version: 20190730:111352 (All versions of this report)

Short URL: ia.cr/2018/319


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