A comparative study on consensus mechanism with security threats and future scopes: Blockchain

Recently, blockchain has emerged as a peer-to-peer (P2P) immutable distributed ledger technology-based network, and its consensus mechanism is playing an important role in managing decentralized data. The use of the consensus process for open blockchains, on the other hand, has revitalized the industry and spurred new architectures. As part of this research, we have analyzed and categorized a wide range of consensus mechanisms in order to contribute to the process of developing blockchain applications and determining the extent of their influence. Critical technical considerations regarding performance, scalability, and other quality aspects that a blockchain-based system must possess may be assisted by this scientific categorization and comprehensive comparison of consensus algorithms. In this paper, we have mainly depicted: (i) proof-of-work (PoW) along with its enhancement rules like greedy heaviest-observed sub-tree (GHOST) and Bitcoin NG (next generation); (ii) proof-of-Stake (PoS) along with chain-based PoS, committee-based PoS, byzantine fault tolerance (BFT) based extended proof-of-stake (EPoS), and delegated proof of stake (DPoS), i.e. energy-efficient alternative to PoW; (iii) BFT consensus to handle crash fault and Byzantine fault; and (iv) hybrid protocols, which are a combination of the best features of PoW, PoS, and BFT consensus mechanism. To evaluate the performance, scalability, security, and design properties of the system, we have considered five components of consensus algorithms.