  Blockchain applications that rely on the Proof-of-Work (PoW) have
increasingly become energy inefficient with a staggering carbon footprint. In
contrast, energy-efficient alternative consensus protocols such as
Proof-of-Stake (PoS) may cause centralization and unfairness in the blockchain
system. To address these challenges, we propose a modular version of PoS-based
blockchain systems called epos that resists the centralization of network
resources by extending mining opportunities to a wider set of stakeholders.
Moreover, epos leverages the in-built system operations to promote fair mining
practices by penalizing malicious entities. We validate epos's achievable
objectives through theoretical analysis and simulations. Our results show that
epos ensures fairness and decentralization, and can be applied to existing
blockchain applications.
