<div>RATIONALES</div><div>Tushar W. et al. wrote a review paper on negawatt trading using
blockchain technology<sup>1</sup>. In their paper, they
introduced consensus management used in the blockchain technology. In
the consensus management<sup>1,2</sup>, four consensus algorithms
are introduced: proof of work, proof of stake, voting based, authority
based, in addition to practical byzantine fault
tolerance<sup>1,3</sup>. Although the security problems lie in
the existing consensus algorithms within the blockchain, such
significant security issues must be addressed in their review paper.</div><div>As far as we know, the decentralized consensus algorithms are all
vulnerable against known attacks including a 51% attack, long range
attack, DDoS attack, P+Epsilon attack, Sybil attack, balance attack, and
BGP hijacking respectively<sup>4,5</sup>. In other words,
blockchain developers and users must understand the vulnerabilities of
the existing consensus algorithms in blockchain. Vulnerability issues in
the blockchain consensus algorithms were detailed<sup>6</sup>.</div><div>Tushar W. et al. should address known security issues of consensus
algorithms in blockchain. In order to use the blockchain technology,
detection and protection mechanisms must be embedded in blockchain
applications for protecting vulnerabilities of known consensus
algorithms.</div><div>References:</div><div>1. Tushar W. et al., Challenges and prospects for negawatt trading in
light of recent technological developments. Nat Energy (2020).</div><div><i>https://doi.org/10.1038/s41560-020-0671-0</i></div><div>2. N. Ul Hassan, C. Yuen and D. Niyato, ”Blockchain Technologies for
Smart Energy Systems: Fundamentals, Challenges, and Solutions,” IEEE
Industrial Electronics Magazine, vol. 13, no. 4, pp. 106-118, Dec. 2019,
doi: 10.1109/MIE.2019.2940335.</div><div>3. M. F. Zia et al., ”Microgrid Transactive Energy: Review,
Architectures, Distributed Ledger Technologies, and Market Analysis,”
IEEE Access, vol. 8, pp. 19410-19432, 2020, doi:
10.1109/ACCESS.2020.2968402.</div><div>4. Sayeed, S.; Marco-Gisbert, H. Assessing Blockchain Consensus and
Security Mechanisms against the 51% Attack. Appl. Sci.2019,9,1788.</div><div>5. Yang, F.; Zhou, W.; Wu, Q.; Long, R.; Xiong, N. N.; Zhou, M.
Delegated Proof of Stake with Downgrade: A Secure and Efficient
Blockchain Consensus Algorithm With Downgrade
Mechanism.IEEEAccess2019,7, 118541−118555.</div><div>6. Yoshiyasu Takefuji, Security Protection Mechanisms Must Be Embedded
in Blockchain Applications, <i>Journal of Chemical Education</i><b>2020</b> <i>97</i> (7), 1819-1820</div><div>DOI: 10.1021/acs.jchemed.0c00040</div>