Abstract

The rapid advent of quantum computing poses a fundamental challenge to classical cryptographic systems that underpin modern digital security. Algorithms such as Shor’s and Grover’s threaten to break widely deployed public-key schemes, including RSA, ECC, and DH, thereby jeopardizing data confidentiality, integrity, and authentication across digital infrastructures. Post-quantum cryptography (PQC) aims to develop security mechanisms resistant to attacks by both classical and quantum adversaries without relying on quantum channels themselves. This paper explores post-quantum security mechanisms, examining lattice-based, code-based, multivariate polynomial, hash-based, and isogeny-based cryptosystems, along with their theoretical foundations, security assumptions, and practical implementations. A comprehensive literature review traces advances in PQC research from early post-quantum proposals to recent standardization efforts by NIST. The research methodology proposes an empirical framework for evaluating post-quantum schemes based on security margins, computational efficiency, key sizes, and integration overhead into existing systems. Advantages and disadvantages of leading PQC mechanisms are analyzed, followed by results and discussion of benchmark implementations and interoperability challenges. The paper concludes by assessing the readiness of PQC in real-world scenarios and outlines future directions for scalable, interoperable, and high-performance post-quantum cryptographic deployments