The incessant escalation of cyber threats, particularly man-in-the-middle (MITM) attacks, has revealed critical vulnerabilities in existing authentication protocols, accentuating an urgent need for more robust security mechanisms. Traditional protocols like SSL/TLS, OAuth, and Kerberos, despite their widespread usage, suffer from inherent cryptographic weaknesses, implementation errors, and protocol loopholes that can be exploited by MITM attacks. This paper proposes an innovative model employing blockchain technology to transcend these limitations and fortify authentication processes. Our approach integrates Public Key Infrastructure (PKI) with blockchain to establish a decentralized system for managing digital certificates, ensuring authenticity and inviolability of public keys. We leverage cryptographic algorithms, notably ECDSA and RSA, for digital signature verification, and employ smart contracts to automate and secure the authentication process, eliminating reliance on centralized authority. Additionally, we implement Decentralized Identity Verification (DID) systems, allowing users to control and share their identity securely. Our methodology includes a comprehensive literature review of current protocols, vulnerability analysis, and the development of blockchain-enhanced protocols. These are rigorously tested in simulated environments against known MITM attack vectors& scenarios. The outcomes are promising, with our blockchain-based protocols significantly enhancing the security and trustworthiness of authentication processes. The decentralized and transparent nature of blockchain improves system resilience against attacks and fraud. Moreover, our protocols demonstrate interoperability and scalability, making them adaptable to various network environments. This res