Quantum-Resilient Security for IoT in 5G/6G Networks: Taxonomy, Performance Trade-Offs, and Migration Roadmap

The deployment of 5G and emerging 6G networks introduces significant security challenges for Internet of Things (IoT) ecosystems comprising billions of heterogeneous devices, including resource-constrained endpoints, more capable embedded controllers, gateways, edge nodes, and network infrastructure. At the same time, the long-term security of widely deployed public-key cryptography is challenged by advances in quantum computing, motivating migration toward standardized post-quantum key-establishment and digital-signature mechanisms. This comprehensive, evidence-based review classifies cryptographic mechanisms for wireless IoT in 5G and beyond across lightweight symmetric cryptography, post-quantum cryptography, privacy-preserving encryption, and adaptive security. The literature-reported implementation results are compared with explicit attention to heterogeneous hardware, memory, energy, communication, and latency constraints. Lightweight symmetric mechanisms remain relevant for constrained data protection, while standardized post-quantum mechanisms such as ML-KEM and ML-DSA address quantum-vulnerable public-key functions and generally introduce larger keys, ciphertexts, signatures, certificates, or protocol messages. This review therefore emphasizes interoperability, firmware upgradability, crypto-agility, and lifecycle management rather than physical device-size growth. A conceptual three-phase roadmap for 2025–2035 is presented in which quantum-vulnerable public-key mechanisms are progressively supplemented and, where appropriate, replaced by hybrid classical–post-quantum and then post-quantum-capable architectures, while standardized symmetric/lightweight protection remains in use where it satisfies application requirements. The roadmap dates are planning intervals rather than universal adoption forecasts.