A Novel Approach Based on Hybrid Quantum Secure Communication System Using X25519 and BB84 Protocol

Abstract

The majority of secure communication systems in use today rely on traditional cryptographic techniques like elliptic curve cryptography and RSA. But if quantum computing advances quickly, these conventional approaches could be more susceptible to assaults in the future. This creates a serious challenge for long-term data security, especially for systems that require strong confidentiality and authentication. Relying only on classical encryption is no longer sufficient, and purely quantum approaches are not yet practical for real-world deployment. Consequently, a well-rounded hybrid solution that incorporates the advantages of both quantum and conventional encryption is required. In this research, we design and implement a hybrid quantum–classical secure communication system between two computers, Alice and Bob, connected over a local network. A simulated BB84 protocol is used to generate a quantum key, while X25519 is applied for classical key exchange. The two keys are combined and processed using HKDF to derive a strong session key. For authentication, Ed25519 digital signatures are used, and secure message transmission is achieved using AES-GCM with a 256-bit key. The implemented system provides confidentiality, integrity, authentication, and improved resistance against future quantum threats.