Secure D2D Communication Framework for Medical Data Transmission Using 5D Chaotic Encryption and HMAC-SHA256 Authentication

As digital interactions expand across industries, robust user authentication systems have become imperative to safeguard against identity theft; data breaches-based approaches have demonstrated significant limitations in usability and security, often leading to poor practices and vulnerabilities. This paper presents a novel dual-factor authentication framework that combines encrypted image-based verification and a multistep One-Time Password (OTP) using a Simple Mail Transfer Protocol (SMTP) mechanism tailored for secure worker-client interaction. The system adheres to current identity verification standards, such as NIST SP 800-63B. It uses the latest two-factor authentication methods to create a strong, multilayered defence against phishing, replay attacks, and fake identities. Experimental evaluation confirms the effectiveness of our approach in real-world scenarios, characterised by minimal latency and high verification accuracy.