**5. Conclusions**

Bitcoin's popularity and success are primarily related to the underlying blockchain technology, which is a genuinely unchanging and highly protected distributed ledger governed by a peer-to-peer consensus. This study conducted a comprehensive analysis to build the hybrid cryptocurrency PoW-PoS, which can resolve the 51% attack in the most feasible and advanced way possible. The proposed hybrid model can prevent the attack by mixing PoW and PoS in one thread with a strict time spacing for block generation to achieve a resilient and robust agreemen<sup>t</sup> amongs<sup>t</sup> P2P network nodes and guarantee a benefit distribution that is in line with stakeholders' investment ratios. The results showed that we successfully implemented a hybrid consensus protocol for blockchain that combines mining and stacking. The hybrid protocol creates a fair mechanism for miners and stakers. Furthermore, each block's period is added to provide a double-spending function for every distribution even though the attacker has more than 51% control over the network. We examined the shortcomings of consensus protocols and security techniques to reveal their main weaknesses. A hybrid model that combines PoW and PoS was then successfully implemented. The system incorporates hardware and economic security without compromising availability, predictability or decentralisation. According to the empirical evidence provided in results Section 4, the proposed protocol is fair and scalable to an arbitrary number of miners and stakes.

In the future, we will conduct a more comprehensive analysis of network stability with additional types of miners and stackers and another simulation based on game theory. A highly economical approach for all mechanisms will also be explored in the future.

**Author Contributions:** Conceptualization, N.A.A. and A.M.; methodology, N.A.A. and A.M.; software, N.A.A.; validation and formal analysis, N.A.A., A.M. and S.M.F.; investigation, A.M. and S.M.F.; writing—original draft preparation, N.A.A. and A.M.; writing—review and editing, S.M.F. and N.E.; visualization, N.A.A. and A.M.; supervision, S.M.F.; project administration, A.M.; Funding N.E. All authors have read and agreed to the published version of the manuscript.

**Funding:** The authors would like to acknowledge the support of Prince Sultan University for paying the article processing charges (APC) of this publication.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable. **Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
