Comparative Analysis of Classical Public-Key Cryptography and NIST-Standardized Post-Quantum Algorithms with a Focus on Migration Strategies

The rapid developments in quantum computing pose a critical threat to classical public-key cryptography, particularly RSA and Elliptic Curve Cryptography (ECC), which rely on mathematical problems solvable by Shor’s algorithm. In response, the National Institute of Standards and Technology (NIST) has standardized quantum-resistant algorithms, including ML-KEM, ML-DSA, FALCON, and SPHINCS+, to prepare global infrastructure for a post-quantum future. This paper provides a unified comparative analysis of classical cryptography and NIST-standardized PQC algorithms, evaluating their security assumptions, efficiency, architectural characteristics, and resilience against quantum adversaries. A comprehensive literature review identifies gaps in existing studies, particularly concerning unified migration frameworks that combine theory, implementation requirements, certificate ecosystem changes, and organizational readiness. To address these gaps, the paper proposes a structured comparative framework and outlines practical migration strategies, including hybrid cryptographic deployment, protocol upgrades, and phased transition roadmaps. The findings highlight that while PQC introduces larger key and signature sizes, its quantum resistance and standardization maturity make it essential for long-term security. The study concludes that strategic migration planning, driven by hybrid adoption and ecosystem adjustments, is crucial for ensuring a secure and seamless transition to post-quantum cryptography