International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 13 Issue: 02 | Feb 2026
p-ISSN: 2395-0072
www.irjet.net
A REVIEW OF ANALYSIS OF CLASSICAL ENCRYPTION ALGORITHMS Vs. POST-QUANTUM CRYPTOGRAPHY TECHNIQUES Mithilesh Kumar1, Mrs. Sahreen Hijab2 1Master of Technology, Computer Science and Engineering, Sagar Institute of Technology and Management,
Barabanki, India
2Assistant Professor, Department of Computer Science and Engineering, Sagar Institute of Technology and
Management, Barabanki, India ---------------------------------------------------------------------***--------------------------------------------------------------------1.1 Evolution of Cryptographic Systems Abstract - The rapid advancement of quantum computing poses a fundamental challenge to classical cryptographic systems that underpin modern digital security. Cryptographic algorithms such as RSA, Diffie–Hellman, and elliptic curve cryptography rely on computational hardness assumptions that are vulnerable to quantum algorithms, notably Shor’s and Grover’s algorithms. This has led to growing research interest in post-quantum cryptography (PQC), which aims to develop cryptographic schemes resistant to both classical and quantum attacks. This review provides a comprehensive analysis of classical encryption algorithms and post-quantum cryptography techniques, examining their security foundations, performance characteristics, and practical deployment considerations. The paper systematically surveys major classes of PQC, including lattice-based, code-based, hash-based, multivariate, and isogeny-based cryptography, with particular emphasis on recent standardization efforts led by the National Institute of Standards and Technology. A comparative evaluation highlights the strengths, limitations, and trade-offs between classical and post-quantum approaches, as well as emerging challenges in scalability, implementation, and migration. The review aims to assist researchers and practitioners in understanding the transition toward quantum-resilient cryptographic infrastructures.
The evolution of cryptographic systems reflects the growing complexity of communication technologies and adversarial capabilities. Early cryptographic methods were primarily based on simple substitution and transposition techniques, offering limited security. With the advent of computers, cryptography transitioned to mathematically grounded algorithms, giving rise to modern symmetric-key and publickey cryptosystems (Stallings, 2017). Symmetric encryption algorithms such as the Data Encryption Standard (DES) and its successor, the Advanced Encryption Standard (AES), were developed to provide efficient data confidentiality. In parallel, public-key cryptography emerged to address key distribution challenges, with seminal contributions including Diffie– Hellman key exchange and the RSA cryptosystem (Diffie and Hellman, 1976; Rivest, Shamir and Adleman, 1978). Elliptic Curve Cryptography later enhanced efficiency by offering equivalent security with smaller key sizes (Koblitz, 1987).
1.2 Impact of Quantum Computing on Cryptographic Security Quantum computing introduces a fundamentally different computational model that exploits quantum-mechanical phenomena such as superposition and entanglement. These capabilities enable new algorithms that significantly outperform classical algorithms for specific problem classes, thereby challenging the security assumptions of classical cryptography.
Key Words: Post-Quantum Cryptography; Classical Encryption Algorithms; Quantum Computing; Cryptographic Security; Lattice-Based Cryptography; NIST Standardization; Quantum-Resistant Algorithms; Secure Communication.
1. INTRODUCTION
1.2.1 Quantum Threats to Classical Cryptographic Assumptions
Cryptography is a cornerstone of modern information security, enabling confidentiality, integrity, authentication, and non-repudiation across digital systems. With the increasing reliance on networked infrastructures, cloud services, and data-driven applications, the robustness of cryptographic mechanisms has become critical. However, emerging computational paradigms, particularly quantum computing, threaten the long-standing assumptions on which classical cryptographic systems are built.
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The security of most public-key cryptosystems relies on the intractability of mathematical problems such as integer factorization and discrete logarithms. Quantum algorithms undermine these assumptions by offering polynomial-time solutions to problems previously considered computationally infeasible (Nielsen and Chuang, 2010).
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