A Unified Approach to Vulnerability Mitigation and Security Enhancement in ECDH-AES-GCM End-to- End Communication

End-to-end communication protocols increasingly rely on elliptic curve Diffie– Hellman (ECDH) combined with AES-GCM for secure key establishment and data protection. While this pairing offers efficiency and strong theoretical security, practical deployments reveal persistent vulnerabilities including unauthenticated ephemeral keys, nonce/IV reuse, naïve key derivation, and weak public-key validation. These flaws enable man-in-the-middle (MITM) attacks, plaintext recovery, and session compromise in real-world systems. This work, analyze these vulnerabilities and propose a unified, implementation-friendly enhancement to the ECDH–AES-GCM framework. The protocol introduces identity-bound authentication of ephemeral keys using static digital signatures (SIGMA-style), HKDF-based key separation with explicit context binding, deterministic nonce derivation via nonceBase ⊕ seq, and strict publickey validation checks. Additionally, optional key confirmation is incorporated to ensure both parties derive identical session keys. Security analysis shows resilience against MITM, replay, and invalid-curve attacks, while preserving forward secrecy. Experimental evaluation demonstrates that the proposed enhancements introduce only minimal computational overhead compared to vanilla ECDH–AES-GCM yet significantly strengthen protocol robustness for browser and constrained environments. This work bridges the gap between theoretical cryptographic guarantees and practical implementation challenges, offering a secure and efficient framework for modern end-to-end encrypted communication.