Secure post-quantum migration requires resistant implementations, authenti-2cated protocols and replaceable systems. This structured critical review synthesises3standards, implementation-security studies, benchmarks, protocol specifications and4deployment measurements available through 19 September 2026. Four instruments5separate mathematical security from implementation assurance, resource feasibility6and organisational readiness: a deployment-security taxonomy, a vulnerability-class7assurance framework, a cross-layer bottleneck map and a layered readiness frame-8work. Comparisons preserve platform, protection and workload context; incompatible9measurements are not pooled. Three boundaries recur: repairing an exploit does10not establish resistance to its vulnerability class; fast primitives do not establish11acceptable end-to-end performance; and hybrid key exchange does not establish12post-quantum authentication or lifecycle readiness. Specification arithmetic makes13the third boundary concrete: two transmitted ML-DSA-65 certificates plus Certifi-14cateVerify contain 13.8 kB of raw cryptographic material, against a 0.32 kB ECDSA15P-256 baseline; the increase is 5.95 times the raw key-share increase for hybrid16over classical X25519 key exchange. These counts exclude encoding and protocol17overhead. A firmware profile screens all 15 FIPS 204/205 signature parameter sets,18retains ML-DSA-65, and shows how the outcome shifts under varied thresholds and19non-FIPS comparators. Source-linked records and executable calculations make the20procedure inspectable. The instruments support conditional engineering judgements,21not independently validated security scores.
Secure post-quantum migration requires resistant implementations, authenti-2cated protocols and replaceable systems. This structured critical review synthesises3standards, implementation-security studies, benchmarks, protocol specifications and4deployment measurements available through 19 September 2026. Four instruments5separate mathematical security from implementation assurance, resource feasibility6and organisational readiness: a deployment-security taxonomy, a vulnerability-class7assurance framework, a cross-layer bottleneck map and a layered readiness frame-8work. Comparisons preserve platform, protection and workload context; incompatible9measurements are not pooled. Three boundaries recur: repairing an exploit does10not establish resistance to its vulnerability class; fast primitives do not establish11acceptable end-to-end performance; and hybrid key exchange does not establish12post-quantum authentication or lifecycle readiness. Specification arithmetic makes13the third boundary concrete: two transmitted ML-DSA-65 certificates plus Certifi-14cateVerify contain 13.8 kB of raw cryptographic material, against a 0.32 kB ECDSA15P-256 baseline; the increase is 5.95 times the raw key-share increase for hybrid16over classical X25519 key exchange. These counts exclude encoding and protocol17overhead. A firmware profile screens all 15 FIPS 204/205 signature parameter sets,18retains ML-DSA-65, and shows how the outcome shifts under varied thresholds and19non-FIPS comparators. Source-linked records and executable calculations make the20procedure inspectable. The instruments support conditional engineering judgements,21not independently validated security scores.
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.
Abstract: This study investigates quantum-safe modernization strategies for critical infrastructure by proposing a rigorous post-quantum (PQ) migration and verification framework that treats cryptographic transition as a safety-critical, multi-system engineering program rather than a routine software upgrade. The core argument is that infrastructure operators face two coupled risks: (i) cryptanalytic obsolescence of classical public-key systems under cryptographically relevant quantum computing and (ii) operational fragility introduced by large-scale cryptographic refactoring across heterogeneous assets such as industrial control systems, substation automation, telecommunications backhaul, and safety instrumentation. To address both, the framework integrates inventory-driven migration planning, hybrid-mode interoperability controls, and verification evidence that is continuously auditable across the asset lifecycle. The manuscript operationalizes verification as a chain of assurance spanning algorithm selection, protocol composition, implementation conformance, and deployment governance. Standardized PQ primitives (e.g., ML‑KEM for key establishment and ML‑DSA/SLH‑DSA for signa-tures) are used as reference baselines, with explicit attention to size and performance implications that alter network and device constraints. Real-data collection is defined as standards-backed parameter extraction, vendor/firmware artifact inspection, and protocol telemetry capture in representative environments. Results are reported as decision-facing tables and figures that quantify payload expansion, transition milestones, and published performance overheads, alongside interpretation of their operational significance for safety and resilience. Keywords: post-quantum cryptography; ML-KEM; ML-DSA; SLH-DSA; CNSA 2.0; critical infrastructure; migration governance; protocol verification; conformance testing; cryptographic agility
The transition to post-quantum cryptography presents enterprises with a complex systems-engineering challenge extending beyond algorithm replacement. Transport Layer Security, public key infrastructure, virtual private networks, cloud-native platforms, identity services, and machine-to-machine communications depend on interconnected cryptographic libraries, certificates, protocols, hardware modules, policies, and vendor products. This review examines crypto-agile migration to hybrid post-quantum cryptography, where classical and quantum-resistant mechanisms are combined to preserve established assurance while emerging algorithms and implementations mature. It develops a migration-oriented taxonomy covering cryptographic discovery, dependency mapping, hybrid key establishment, composite authentication, certificate lifecycle management, protocol negotiation, performance optimization, interoperability testing, and operational governance. Particular attention is given to larger keys, ciphertexts, and signatures; handshake fragmentation; certificate-chain expansion; hardware acceleration; legacy compatibility; downgrade resistance; and observability across distributed environments. The review compares migration requirements in enterprise TLS, PKI, remote-access and site-to-site VPNs, service meshes, API gateways, container platforms, serverless services, secrets systems, and multicloud infrastructures. It also analyzes staged deployment patterns, including inventory-first modernization, proxy-based termination, dual certificates, hybrid tunnels, algorithm-policy abstraction, and controlled fallback. Evaluation criteria integrate security, interoperability, latency, throughput, bandwidth, memory, certificate issuance, operational resilience, and rollback readiness. The findings indicate that successful migration depends on treating cryptography as a continuously governed enterprise capability rather than a fixed protocol configuration. The paper concludes by identifying gaps in standardization, automated discovery, cross-vendor testing, cryptographic telemetry, constrained-device support, and lifecycle evidence, providing organizations with a structured foundation for prioritized, reversible, and verifiable post-quantum transformation across heterogeneous digital services. Keywords: Crypto-Agility, Hybrid Cryptography, Post-Quantum Cryptography, Public Key Infrastructure, Quantum-Safe Migration, Transport Layer Security.
Large-scale quantum computers would invalidate the hardness assumptions behind many deployed public key cryptosystems and reduce the effective strength of symmetric primitives. As a result, governments and industry have begun a multi-year transition toward post quantum cryptography and quantum safe protocols. This survey provides a structured overview of that transition. It classifies the main families of post quantum schemes, with emphasis on the standardized lattice based and hash-based algorithms ML-KEM, ML-DSA, SLH-DSA, FALCON and Classic McEliece, and it summarizes their parameter sets, key sizes, ciphertext or signature lengths and performance profiles across the NIST security categories. The survey then reviews stateful hash-based signatures, multivariate and isogeny-based proposals and emerging MPC in the head constructions and discusses their security assumptions and level of maturity. At the protocol level it analyzes hybrid designs for TLS 1.3, QUIC, IPsec, SSH and public key infrastructures and draws lessons from early deployments in web, IoT, and cloud environments. By collating detailed parameter data from recent NIST standards and reference implementations and mapping them to concrete deployment scenarios, the survey links high-level policy guidance to engineering choices. The paper also synthesizes cross cutting implementation and migration challenges, including side channel resistance, cryptographic agility, asset inventory and migration planning, and algorithm diversity across deployments. Finally, it identifies open problems such as leakage resilient implementations, domain specific post quantum profiles for constrained devices and combinations of post quantum cryptography with quantum key distribution. The goal is to give researchers and practitioners a coherent reference that connects algorithms, standards, protocol mechanisms and deployment guidance for building quantum safe systems.
Internet public-key cryptography faces long-term risk from quantum computers, especially when traffic can be collected now and decrypted later. After the NIST post-quantum cryptography standards, the deployment task has shifted from algorithm selection to protocol migration. This paper reviews ML-KEM hybrid key exchange in TLS and SSH through a standards-first narrative review and protocol comparison. It synthesizes NIST standards, RFCs and IETF drafts, experiments, measurements, and primary deployment reports. The paper develops a deployment-readiness framework with four layers: security continuity, protocol integration, operational observability, and crypto-agility. The analysis shows hybrid key exchange represents the most feasible short-term solution, as it introduces post-quantum confidentiality without discarding existing elliptic curve security guarantees. However, hybrid deployment does not provide full post-quantum security. The review argues that readiness depends on protocol binding, implementation behavior, monitoring, and governance as much as on algorithm strength. Handshake size, middlebox compatibility, implementation safety, telemetry, authentication migration, and organizational crypto-agility determine whether migration can progress without weakening current Internet security.
Post-quantum cryptography (PQC) is moving from evaluation to deployment as NIST finalizes standards for ML-KEM, ML-DSA, and SLH-DSA. This survey maps the space from foundations to practice. We first develop a taxonomy across lattice-, code-, hash-, multivariate-, isogeny-, and MPC-in-the-Head families, summarizing security assumptions, cryptanalysis, and standardization status. We then compare performance and communication costs using representative, implementation-grounded measurements, and review hardware acceleration (AVX2, FPGA/ASIC) and implementation security with a focus on side-channel resistance. Building upward, we examine protocol integration (TLS, DNSSEC), PKI and certificate hygiene, and deployment in constrained and high-assurance environments (IoT, cloud, finance, blockchain). We also discuss complementarity with quantum technologies (QKD, QRNGs) and the limits of near-term quantum computing. Throughout, we emphasize crypto-agility, hybrid migration, and evidence-based guidance for operators. We conclude with open problems spanning parameter agility, leakage-resilient implementations, and domain-specific rollout playbooks. This survey aims to be a practical reference for researchers and practitioners planning quantum-safe systems, bridging standards, engineering, and operations.