Useful work: a new protocol to ensure usefulness of PoW-based consensus for blockchain

Abstract

The blockchain is a new technology that attracts several actors since 2009, and in particular in the financial domain with the emergence of cryptocurrencies such as the well-known Bitcoin. In a blockchain, seen also as a distributed ledger or a chain of blocks, the participants use a consensus protocol to add new data into the ledger. For example, in the Bitcoin Proof-of-Work consensus protocol, the participants have to unnecessarily invest a huge amount of energy to add a new block of transactions, and therefore to also win the coin associated to this block. Several consensus protocols have been proposed to overcome this waste and resource intensive process. In this paper, we present a new consensus protocol for blockchain technologies called Useful Work (UW). Our UW protocol is based on the Proof-of-Stake and Proof-of-Work mechanisms where the computing work is dedicated to useful problems. The participants get a chance to win coins after performing honest and useful work for a submitted problem. We present a high-level description of our UW protocol that is configurable and propose some variants of the protocol. We discuss also some new and well-known issues that our protocol prevents.