## Cryptology ePrint Archive: Report 2019/985

ETHDKG: Distributed Key Generation with Ethereum Smart Contracts

Philipp Schindler and Aljosha Judmayer and 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. We hereby aim to close this gap by presenting an open source, fully functional, well documented, and economically viable DKG implementation that employs Ethereum's smart contract platform as a communication layer. The efficiency and practicability of our protocol is demonstrated through the deployment and successful execution of a DKG contract in the Ropsten testnet. Given the current Ethereum block gas limit, it is possible to support up to $256$ participants, while still ensuring that the key generation process can be verified at smart contract level. Further, we present a generalization of our underlying DKG protocol that is suitable for distributed generation of keys for discrete logarithm based cryptosystems.

Category / Keywords: cryptographic protocols / Distributed Key Generation, DKG, Ethereum