RANDGENER: Distributed Randomness Beacon from Verifiable Delay Function

Abstract: Buoyed by the excitement around secure decentralized applications, the last few decades have seen numerous constructions of distributed randomness beacons (DRB) along with use cases; however, a secure DRB (in many variations) remains an open problem. We further note that it is natural to want some kind of reward for participants who spend time and energy evaluating the randomness beacon value -- this is already common in distributed protocols. In this work, we present RandGener, a novel $n$-party commit-reveal-recover (or collaborative) DRB protocol with a novel reward and penalty mechanism along with a set of realistic guarantees. We design our protocol using trapdoor watermarkable verifiable delay functions in the RSA group setting (without requiring a trusted dealer or distributed key generation).