A Comparative Study of Classical Cryptography and Post-Quantum Cryptographic Algorithms

Varshini B M, Dr. Umadevi Ramamorthy

Abstract: The rapid progress of quantum computing is changing the assumptions on which many modern security systems are built. Public-key methods such as RSA and Elliptic Curve Cryptography (ECC) remain dependable against conventional computers, yet their underlying mathematical problems can be solved efficiently by a sufficiently capable quantum computer using algorithms such as Shor's algorithm. This creates a practical need to evaluate cryptographic techniques that can continue to protect information in a post-quantum environment. This study compares representative classical algorithms - RSA, ECC, and the Advanced Encryption Standard (AES) - with post-quantum approaches, with particular attention to CRYSTALS-Kyber and CRYSTALS-Dilithium. The comparison considers security assumptions, key-generation cost, encryption and decryption time, key size, memory demand, and resistance to quantum attacks. The reported benchmark values indicate that RSA has the highest processing cost among the evaluated schemes, whereas CRYSTALS-Kyber provides comparatively fast key generation, encryption, and decryption while maintaining resistance to known quantum attacks. The study also discusses a hybrid migration model in which established classical mechanisms and post-quantum algorithms operate together during the transition period. Overall, the findings support a gradual move toward quantum-resistant communication systems while recognising the deployment and storage overhead introduced by larger post-quantum keys.

Keywords: Quantum computing, post-quantum cryptography, lattice-based cryptography, CRYSTALS-Kyber, CRYSTALS-Dilithium, RSA, ECC, AES, security strength

How to Cite?: Varshini B M, Dr. Umadevi Ramamorthy, "A Comparative Study of Classical Cryptography and Post-Quantum Cryptographic Algorithms", Volume 15 Issue 9, September 2026, International Journal of Science and Research (IJSR), Pages: 514-520, https://www.ijsr.net/getabstract.php?paperid=MR26908183004, DOI: https://dx.doi.org/10.21275/MR26908183004

Download Citation: APA | MLA | BibTeX | EndNote | RefMan