[Paper Review] Feasibility of Proof of Authority as a Consensus Protocol Model

Shashank Joshi|arXiv (Cornell University)|Aug 30, 2021

Blockchain Technology Applications and Security5 references35 citations

TL;DR

The paper analyzes the feasibility of Proof of Authority (PoA) as a consensus model, comparing it with PoW and PoS, and discusses advantages, limitations, and suitable use cases for PoA in private/permissioned blockchains.

ABSTRACT

Blockchain is a type of decentralized distributed network which acts as an immutable digital ledger. Despite the absence of any central governing authority to validate the blocks in the ledger, it is considered secure and immutable due to the consensus protocol among various nodes of the network. A consensus algorithm is a mechanism that guarantees the reliability of the blockchain and helps all connected nodes or peers to reach common ground regarding the present state of the blockchain network thus an ideal consensus algorithm must be secure, reliable, and fast. There are several different algorithms to reach a consensus among the nodes thus this article seeks to test the practicality of Proof of Authority in the blockchain network as a consensus algorithm and its comparison with current mainstream consensus algorithms.

Motivation & Objective

• Motivate the exploration of PoA as an alternative to PoW and PoS due to scalability and efficiency concerns.
• Examine the core principles and architecture of PoA, including reputation-based validation and sealers.
• Compare PoA with PoW and PoS to illuminate trade-offs in decentralization, throughput, and security.
• Identify suitable application contexts (private/permissioned blockchains, notary-based apps) for PoA.

Proposed method

• Describe the PoA mechanism as a permissioned consensus with a fixed set of validators called sealers.
• Discuss how reputation, liveliness, tolerance, monotonicity, visibility, and selection process influence PoA security and operation.
• Provide qualitative comparisons to PoW and PoS focusing on throughput, scalability, and resource use.
• Outline expected security implications such as Byzantine fault tolerance and potential attacks (Sybil, cloning).

Experimental results

Research questions

• RQ1 What is Proof of Authority and how does it operate as a consensus protocol?
• RQ2 How does PoA compare to PoW and PoS in terms of throughput, scalability, and resource usage?
• RQ3 What are the main advantages and limitations of PoA for different blockchain contexts?
• RQ4 For which applications or network models is PoA most suitable (e.g., private or permissioned blockchains, notary-based apps)?

Key findings

• PoA is a reputation-based, permissioned consensus with a limited set of validators (sealers).
• PoA offers higher throughput and scalability with lower resource consumption than PoW and PoS.
• PoA can maintain stable transaction fees and is well-suited for DApps and private networks.
• PoA sacrifices decentralization and introduces identity visibility and potential censorship risks.
• PoA is susceptible to Sybil and cloning attacks and relies on robust reputation mechanisms.
• PoA security hinges on liveliness, tolerance, monotonicity, and transparent sealer selection.