On PeerCoin Proof of Stake for Blockchain Consensus

Abstract

Proof of Stake (PoS) has been talked about extensively as an alternative way of reaching consensus in blockchain systems. However, there are few publications on how PoS can be used to create new blocks in detail. The undisputed lead proponent for PoS is Ethereum. However, virtually all discussions regarding PoS for Ethereum are centered on selecting a block using PoS after one or more candidate blocks have already been somehow created. PeerCoin was the first blockchain system that incorporated PoS in block creation. Unfortunately, there is no known documentation on how PoS works in PeerCoin. In this paper, we fill this gap by presenting a detailed explanation of the PeerCoin PoS algorithm based on PeerCoin source code. We also dispel the misconception that PeerCoin PoS is based on Proof of Work (PoW) and hence would consume a lot of energy just like proof of work (PoW). In fact, it resembles PoW only on surface and differs from PoW substantially in terms of how to meet the difficulty target.