Paper 2019/985

EthDKG: Distributed Key Generation with Ethereum Smart Contracts

Philipp Schindler, Aljosha Judmayer, Nicholas Stifter, and Edgar Weippl

Abstract

Distributed key generation (DKG) is a fundamental building block for a variety of cryptographic schemes and protocols, such as threshold cryptography, multi-party coin tossing schemes, public randomness beacons and consensus protocols. More recently, the surge in interest for blockchain technologies, and in particular the quest for developing scalable protocol designs, has renewed and strengthened the need for efficient and practical DKG schemes. Surprisingly, given the broad range of applications and available body of research, fully functional and readily available DKG protocol implementations still remain limited. This paper hereby aims to close this gap by tailoring Gennaro et al.'s well known protocol design towards being efficiently implementable within public cryptocurrency ecosystems such as Ethereum. Our theoretical improvements are supported by an open source, fully functional, well documented DKG implementation that can employ any Ethereum Virtual Machine (EVM) compatible smart contract platform as a communication layer. We evaluate the efficiency of our protocol and demonstrate its practicability through the deployment and successful execution of our DKG contract in the Ethereum Ropsten testnet. Given the current Ethereum block gas limit, all steps required for the key generation process, even in demanding scenarios tested with up to 256 nodes, can be verified at the smart contract level.