## 5 Conclusions  
This study presents a comprehensive review and systematic analysis of blockchain-based data storage methods, evaluating their security, scalability, and cost trade-offs. By classifying on-chain, off-chain, and hybrid storage approaches, this research has highlighted their advantages, limitations, and industry-specific applications. Furthermore, the study has examined the security challenges associated with blockchain storage and discussed cryptographic mechanisms that enhance data protection. Key Insights and Implications. * Hybrid storage solutions have emerged as a critical approach for balancing security, scalability, and cost efficiency in blockchain-based data management. While on-chain storage ensures data integrity and transparency, its scalability issues remain a bottleneck. Conversely, off-chain storage offers cost efficiency but poses challenges in decentralization and trust management. Hybrid models present a promising trade-off, particularly for use cases that demand both security and high-volume data processing. * Layer-2 solutions have been identified as a viable method to enhance blockchain storage efficiency. Rollups, state channels, and sidechains demonstrate potential in reducing on-chain storage loads while maintaining security guarantees. However, their adoption across industries remains a challenge due to interoperability constraints and regulatory concerns. * The security evaluation of blockchain storage mechanisms underscores the importance of cryptographic techniques such as Zero-Knowledge Proofs (ZKP), Homomorphic Encryption, and advanced access control models (RBAC, ABAC). These mechanisms play a crucial role in ensuring data confidentiality and integrity, particularly in sectors like healthcare, finance, and IoT. * Decentralized storage networks (Filecoin, Arweave, Swarm, Sia, Storj) provide an alternative to traditional blockchain storage by leveraging distributed infrastructures for secure and scalable data management. However, their economic and governance models still require further optimization to achieve broader adoption in enterprise environments. * Sectoral analysis of blockchain storage applications reveals that healthcare, finance, and IoT industries benefit the most from blockchain's secure and immutable architecture. However, regulatory frameworks, privacy concerns, and energy consumption challenges remain key barriers to mass adoption. Implications and Future Directions Based on these findings, future research should address the following critical areas:
* Optimizing hybrid blockchain storage models to maximize efficiency and security without compromising decentralization;
* Developing standardized interoperability protocols to enable seamless data exchange between different blockchain networks;
* Enhancing quantum-resistant cryptographic techniques to future-proof blockchain storage against emerging computational threats;
* Evaluating real-world implementation challenges and assessing the economic feasibility of blockchain storage solutions in various industries;
* Addressing regulatory and compliance challenges to facilitate broader adoption of blockchain storage technologies in highly sensitive domains;
* Edge Computing and Internet of Everything (IoE) should be studied for their potential in enhancing blockchain storage scalability and efficiency. This study contributes to the field by systematically classifying blockchain storage approaches, identifying security trade-offs, and presenting a structured research roadmapfor future exploration. The insights gained from this study provide a foundation for improving the design and adoption of secure, scalable, and cost-efficient blockchain-based data storage solutions. Conceptualization and problem definition: H.E., O.K. and M.T.G. ; Development of blockchain storage classification: H.E., O.K. and M.T.G. ; Sectoral analysis of blockchain storage methods: O.K. and H.E. ; Comparative analysis of on-chain, off-chain, and hybrid storage methodologies: H.E. and O.K.