A Comment on "e-PoS: Making PoS Decentralized and Fair"

TL;DR

The comment challenges the PoS interpretation used in Saad et al.'s e-PoS, arguing it does not reflect standard PoS implementations in real PoS cryptocurrencies. By examining multiple PoS coins, it identifies a common stake-based probability framework and highlights that Saad et al.'s probability model can yield a deterministic attacker advantage, unlike real-world PoS where block leadership probability $p_i$ is proportional to stake $s_i$ via $p_i = s_i / \sum_k s_k$. Consequently, the paper contends that decentralization and fairness concerns attributed to conventional PoS are not present, implying e-PoS addresses a mischaracterized problem. The discussion clarifies the distinction between theoretical PoS models and actual PoS deployments, with implications for evaluating new PoS protocols.

Abstract

Proof-of-Stake (PoS) is a prominent Sybil control mechanism for blockchain-based systems. In "e-PoS: Making PoS Decentralized and Fair," Saad et al. (TPDS'21) introduced a new Proof-of-Stake protocol, e-PoS, to enhance PoS applications' decentralization and fairness. In this comment paper, we address a misunderstanding in the work of Saad et al. The conventional Proof-of-Stake model that causes the fairness problem does not align with the general concept of Proof-of-Stake nor the Proof-of-Stake cryptocurrencies mentioned in their paper.