The Google Quantum AI whitepaper [1] established that the secp256k1 elliptic curve discrete logarithm problem (ECDLP-256) the signature primitive securing the majority of public blockchain networks can be broken with fewer than 500,000 physical qubits in approximately nine minutes on a fast-clock cryptographically relevant quantum computer (CRQC), a roughly 20-fold reduction from prior estimates. That analysis addresses cryptocurrency nodes and does not model the structurally distinct risk profile of IoT/WSN nodes participating in blockchain networks. This paper closes that gap. We demonstrate that gateway-mediated transaction submission, combined with the duty-cycle wakeup latency endemic to IEEE 802.15.4-class sensor nodes, can extend the on-spend attack window beyond Bitcoin’s ten-minute block time making constrained WSN nodes more vulnerable to on-spend attacks than standard cryptocurrency clients for certain deployment configurations. We introduce a formal HNDL Risk Score (HRS) that jointly quantifies harvest-now/decrypt-later exposure, on-spend vulnerability, and migration feasibility as a function of node hardware class and deployment lifespan. We benchmark all four NIST-standardised post-quantum cryptography algorithms (ML-KEM-512, ML-DSA-44, FN-DSA/FALCON-512, SLH-DSA-128s) on representative WSN hardware (Raspberry Pi Pico RP2040 and ESP32) and identify FN-DSA/FALCON-512 as the superior candidate for WSN-blockchain transaction authentication, offering 666-byte signatures at 71.6 ms mean signing time on Cortex-M0+ hardware. A concrete, tiered migration roadmap is proposed for healthcare WSN, industrial IIoT, and smart city sensor deployments.
The Google Quantum AI whitepaper [1] established that the secp256k1 elliptic curve discrete logarithm problem (ECDLP-256) the signature primitive securing the majority of public blockchain networks can be broken with fewer than 500,000 physical qubits in approximately nine minutes on a fast-clock cryptographically relevant quantum computer (CRQC), a roughly 20-fold reduction from prior estimates. That analysis addresses cryptocurrency nodes and does not model the structurally distinct risk profile of IoT/WSN nodes participating in blockchain networks. This paper closes that gap. We demonstrate that gateway-mediated transaction submission, combined with the duty-cycle wakeup latency endemic to IEEE 802.15.4-class sensor nodes, can extend the on-spend attack window beyond Bitcoin’s ten-minute block time making constrained WSN nodes more vulnerable to on-spend attacks than standard cryptocurrency clients for certain deployment configurations. We introduce a formal HNDL Risk Score (HRS) that jointly quantifies harvest-now/decrypt-later exposure, on-spend vulnerability, and migration feasibility as a function of node hardware class and deployment lifespan. We benchmark all four NIST-standardised post-quantum cryptography algorithms (ML-KEM-512, ML-DSA-44, FN-DSA/FALCON-512, SLH-DSA-128s) on representative WSN hardware (Raspberry Pi Pico RP2040 and ESP32) and identify FN-DSA/FALCON-512 as the superior candidate for WSN-blockchain transaction authentication, offering 666-byte signatures at 71.6 ms mean signing time on Cortex-M0+ hardware. A concrete, tiered migration roadmap is proposed for healthcare WSN, industrial IIoT, and smart city sensor deployments.
Abstract—The advent of fault-tolerant Cryptanalytically Relevant Quantum Computers (CRQCs) presents an existential threat to modern information security. Shor's polynomial-time quantum algorithm renders widely deployed public-key cryptographic primitives—including RSA, Diffie-Hellman (DH), and Elliptic Curve Cryptography (ECDH/ECDSA)—completely vulnerable to private key derivation. Furthermore, 'Harvest Now, Decrypt Later' (HNDL) adversarial campaigns actively intercept and store encrypted enterprise telemetry today, anticipating future quantum decryption capabilities. In response, the National Institute of Standards and Technology (NIST) finalized its primary Post-Quantum Cryptography (PQC) standards in FIPS 203 (ML-KEM), FIPS 204 (ML-DSA), and FIPS 205 (SLH-DSA). However, transitioning complex enterprise IT ecosystems to quantum-resistant primitives introduces severe architectural and computational disruptions: public key and signature sizes increase by several orders of magnitude, cryptographic handshake latencies escalate, network packets experience Maximum Transmission Unit (MTU) fragmentation, and legacy Hardware Security Modules (HSMs) lack microarchitectural support for lattice-based polynomial arithmetic. This paper provides an exhaustive, mathematically grounded technical survey and architectural roadmap for enterprise PQC migration. We formalize the Module Learning with Errors (M-LWE) and Module Short Integer Solution (M-SIS) hardness foundations, evaluate hybrid classical/post-quantum cryptographic transition models across standard transport protocols (TLS 1.3, IKEv2/IPsec, SSH), and formulate an enterprise Crypto-Agility Maturity Model. Furthermore, we construct an empirical enterprise testbed measuring throughput, connection establishment latency, memory footprints, and packet fragmentation across legacy and quantum-resistant suites. Our results show that while ML-KEM-768 achieves microsecond-level encapsulation, its 1,088-byte ciphertext expands TLS ClientHello payloads into multiple TCP segments under constrained networks. Finally, we establish open research directions in post-quantum identity federations, stateful hash signature tracking, and hardware-accelerated polynomial arithmetic. Index Terms—Post-Quantum Cryptography (PQC), FIPS 203 (ML-KEM), FIPS 204 (ML-DSA), Crypto-Agility, TLS 1.3, Lattice-Based Cryptography, Harvest Now Decrypt Later, Hardware Security Modules (HSM), Enterprise Migration.
Quantum computing poses a significant threat to Wireless Sensor Networks (WSNs) by undermining traditional cryptographic algorithms such as RSA and Elliptic Curve Cryptography (ECC). This work proposes a quantum-safe architecture for WSNs that integrates post-quantum cryptography (PQC) with lightweight IoT protocols to ensure long-term confidentiality, authenticity, and resilience. The framework leverages ML-KEM for key encapsulation and ML-DSA/SLH-DSA for signatures, and seamlessly integrates with EDHOC, OSCORE, and COSE. A novel Efficient Adaptive Parameter Selection (EAPS) mechanism dynamically adjusts cryptographic strength to balance security, energy consumption, and latency under varying network conditions. Experimental evaluation demonstrates that ciphertext fragmentation (8–27 pieces) results in manageable completion times of 4–10 seconds, while join operations consume only 0.005–0.03 J per cryptographic handshake event, while system-level energy consumption including network overhead is higher (~1.0–1.4 J per join cycle depending on hop count and retransmissions). Battery lifetime projections under steady-state sensing workloads range from approximately 115–280 months for low-duty-cycle operation, whereas realistic deployment conditions with periodic communication yield effective lifetimes of 11.5–24 months. Security analysis confirms robust resistance against downgrade attacks and Harvest-Now-Decrypt-Later (HNDL) threats. Moreover, EAPS reduces risk scores by over 50% compared to fixed schemes with less than 10% additional energy overhead, and batch signature verification improves scalability by increasing throughput from ~1,600 to ~2,800 verifications per second. Overall, the proposed framework demonstrates that WSNs can achieve quantum-resistant security with minimal performance trade-offs, ensuring readiness for the post-quantum era.
ABSTRACT Smart cities are built on a vast interconnected network of Internet of things (IoT), edge and cloud systems to optimise urban services and enhance the quality of life for the residents. However, this integration of cyber‐physical infrastructure expands the attack surface, making it vulnerable to advanced cyber threats. The most notable emerging threat is quantum computers, which can break the classical cryptographic algorithms, such as RSA and ECC, that form the foundation of cybersecurity. Integrating liboqs execution benchmarks with an analytical network fragmentation model simulated with NS‐3, evaluating NIST‐approved PQC key encapsulation mechanisms, ML‐KEM (Kyber512/768/1024), HQC (128/192/256) and classic McEliece variants, alongside signature schemes ML‐DSA (Dilithium), Falcon and SLH‐DSA (SPHINCS+) within a smart city network. We also extended the benchmarking to include NIST's SP 800‐230 draft and provide preliminary benchmarks of the six new parameter sets. To assess embedded feasibility, all algorithms are additionally executed on the ESP32 P4 microcontroller, measuring timing, energy consumption and memory under resource‐constrained conditions. This dual platform methodology enables cross‐validation of network‐level overhead and hardware‐level performance. Results show consistent behaviour across platforms. ML KEM 512 (NIST Security Level 1) provides the best KEM performance, with key generation at 7.2 µs (NS‐3) and 122.6 ms (ESP32 P4), and similarly efficient encapsulation/decapsulation. ML DSA 44 (NIST Security Level 2) achieves the fastest signatures at 64 µs on NS‐3 and 490.6 ms on ESP32 P4. These findings provide evidence‐based guidelines for deploying postquantum cryptography across smart city IoT–Edge–Cloud infrastructures, emphasising crypto‐agility and hybrid cryptography for smart city networks.
The emergence of cryptographically relevant quantum computers (CRQCs) would compromise today’s dominant public-key primitives (RSA, DiffieHellman, ECDSA), threatening long-lived confidentiality, authentication, and integrity guarantees across AI pipelines and blockchain networks. This manuscript proposes a unified, quantum-resilient architecture that blends NISTstandardized post-quantum cryptography (PQC)—MLKEM for key establishment and ML-DSA or SLH-DSA for digital signatures—with defense-in-depth controls for AI model protection, data privacy, and blockchain protocol evolution. We first motivate the need for migration by outlining quantum attacks (Shor for factoring and discrete logarithms; Grover for quadratic search speedups) and summarize PQC standardization milestones and transition guidance. We then review the literature on lattice-based and hash-based cryptography, homomorphic encryption for privacy-preserving AI, and secure aggregation/differential privacy as complementary privacy technologies. Building on this foundation, we present a methodology for designing and evaluating quantum-resistant AI and blockchain systems, including key-lifecycle hardening, protocol-level hybrids, and crypto-agility. A simulated deployment (1,000 clients; 16 validator nodes; TLS 1.3 with ML-KEM and hybrid handshakes; blockchain transactions signed with ML-DSA and SLH-DSA) measures handshake and signing overheads, throughput, and model-training privacy-utility trade-offs. Results indicate that: (i) PQC-only handshakes add modest latency yet remain acceptable for online APIs; (ii) hybrid ECDHE+ML-KEM offers near-term defense against “store-now-decrypt-later,” with predictable cost; (iii) ML-DSA is practical for blockchain validation at common block sizes, while SLH-DSA suits firmware/codesigning and archival integrity; and (iv) combining PQC with secure aggregation and differentially private training preserves model utility with bounded overhead.
The prospect of a cryptographically relevant quantum computer (CRQC) undermines the public-key primitives that secure virtually every layer of modern communication networks, from subscriber authentication in cellular cores to transport-layer key exchange. Adversaries already following a harvest-now, decrypt-later (HNDL) strategy make this threat actionable today for any traffic whose confidentiality must outlast a decade. Following NIST’s finalisation of the first post-quantum cryptography (PQC) standards, ML-KEM (FIPS 203), ML-DSA (FIPS 204), and SLH-DSA (FIPS 205) in August 2024, and the selection of HQC as a fourth key-encapsulation candidate in March 2025, research has shifted from algorithm design to network-level integration. This paper reports a PRISMA-2020-compliant systematic literature review of PQC migration in communication networks, structured around five research questions covering protocol and scenario coverage, quantitative performance impact, hybrid cryptography strategies, transition barriers, and open research gaps. Six databases (IEEE Xplore, Scopus, Web of Science, ACM Digital Library, SpringerLink, and MDPI) were searched (3229 records identified); after deduplication, title-keyword screening, full-text eligibility assessment, and a pre-specified quality appraisal (Q1–Q6, threshold ≥3/6) applied to 310 eligible studies, a final synthesis corpus of 141 studies (68 journal articles, 68 conference papers, 4 conference-derived book chapters, 1 workshop paper) was screened, quality-appraised, and synthesised narratively with supporting evidence tables. The review finds that transport-layer protocols (TLS 1.3, QUIC, DTLS 1.3) dominate the literature, that lattice-based ML-KEM/ML-DSA offer the most favourable latency–bandwidth–energy trade-off among standardised families, and that classical–PQC hybrid schemes are the de facto transition strategy across 5G/6G, IoT, VPN, and automotive scenarios, at the cost of 10–100× larger keys/signatures and 8–40% handshake latency overhead. Persistent barriers include constrained-device resource limits, immature hardware acceleration, incomplete IETF/3GPP standardisation, and public-key-infrastructure scaling. We propose a five-level PQC transition-readiness maturity model and identify large-scale field validation, PQC–QKD integration, and lightweight signature schemes as priority directions for future work.
Large-scale quantum computers threaten the public-key cryptography that protects enterprise data, communications, and digital identity. Shor's algorithm solves integer factorization and discrete logarithms in polynomial time, which would break RSA, Diffie-Hellman, and elliptic-curve schemes once a cryptographically relevant quantum computer exists. The danger is not only future. Adversaries can record encrypted traffic today and decrypt it later, a tactic known as harvest-now-decrypt-later. In August 2024 the U.S. National Institute of Standards and Technology published its first post-quantum standards: FIPS 203 (ML-KEM, derived from CRYSTALS-Kyber), FIPS 204 (ML-DSA, from CRYSTALS-Dilithium), and FIPS 205 (SLH-DSA, from SPHINCS+). This paper presents a practical migration framework for enterprises. It reviews the quantum threat and Mosca's inequality for timing the transition, summarizes the new standards with their key and signature sizes, and proposes a five-phase roadmap built on crypto-agility: discovery and inventory, risk prioritization, agility engineering, hybrid deployment, and validation. Performance trade-offs are analyzed using documented parameter sizes and illustrative TLS handshake figures. ML-KEM-768 carries a 1,184-byte public key against 64 bytes for an elliptic-curve key, while SPHINCS+ signatures can exceed 17 kilobytes. The work does not report a real deployment. It consolidates published parameters and field guidance into an actionable plan, and it highlights open challenges in certificate sizing, hardware support, and long-lived embedded systems.