Blockchain-Based Security Mechanisms for Decentralized Identity and Authentication: A Comprehensive Review
The rapid spread of digital technology has highlighted the weaknesses of traditional centralized systems, which often suffer from single points of failure, data breaches, and a lack of user control. This has created a strong need for more secure, open, and user-focused alternatives. Blockchain technology has emerged as a powerful solution, providing a decentralized, unchangeable, and cryptographically secure way to manage data and transactions without needing trusted middlemen. This review article looks at the research on how blockchain is used to create decentralized identity and authentication systems. We analyze basic frameworks, from protocols for IoT to solutions for securing cloud storage and document version control. The review also explores how blockchain is used in other fields, like how it improves security in federated learning and a theoretical look at its role in a post-quantum world. The discussion critically examines key challenges such as the scalability problem and the trade-off between privacy and openness. By highlighting these insights and suggesting future research, this paper aims to provide a clear roadmap for using blockchain to build strong and trustworthy decentralized systems.