A COMPREHENSIVE REVIEW OF POST-QUANTUM CRYPTOGRAPHY FOR SECURE COMMUNICATION IN INTERNET OF THINGS

Large-scale quantum computers, once realized, threaten the mathematical foundations on which today’s public-key infrastructure is built. Widely deployed schemes such as RSA and Elliptic Curve Cryptography depend on number-theoretic problems that quantum algorithms are expected to solve effi-ciently, motivating a decade-long effort to design cryptographic primitives that resist both classical and quantum adversaries. This survey brings together that effort under a single lens, tracing the reasoning behind post-quantum cryptography (PQC) from its theoretical origins to its practical deployment. We begin by clarifying why quantum computation undermines classical hardness assumptions, then walk through the four major PQC families – lattice-based, code-based, hash-based, and multivariate constructions – weighing each against the others on security assurance, computational cost, and ease of implementation. The discussion then turns outward to where PQC is actually being tested: Internet of Things deployments, blockchain ledgers, and AI-assisted defense pipelines, drawing on recent proposals in each area. We close by consolidating the recurring obstacles reported across this literature – oversized keys, added computational burden, and friction with legacy protocols – into a set of concrete directions for researchers aiming to make quantum-resistant security practical rather than merely theoretical.