The August 2024 finalisation of FIPS 203 (ML-KEM), FIPS 204 (ML-DSA), and FIPS 205 (SLH-DSA) closed the algorithmic gap in post-quantum cryptography (PQC). The production gap -- hybrid combiners, versioned key formats, protocol helpers, and migration tooling -- remains open. We present quantum-safe, a Python library that closes all three critical gaps we identify, and a systematic evaluation of the nine-library ecosystem that quantifies them.
We score nine PQC libraries across eight production-readiness dimensions. Three dimensions have coverage below 35%: hybrid KEM support (11%), migration tooling (22%), and protocol integration (33%). quantum-safe scores Full on all eight. The full API reduces the hybrid KEM task from 45 lines of manual combiner code to three lines, directly lowering the risk of insecure combiner implementations.
We report the first statistically rigorous per-operation overhead measurement for a Python hybrid PQC library (3,000 iterations, CPU-pinned, bootstrapped 95% confidence intervals). A full X25519 + ML-KEM-768 handshake completes in 243 μs under Docker/Linux -- 0.5--2.5% of a typical TLS 1.3 round-trip budget. At 5,000 concurrent users, throughput holds at 2,848 ops/s with only 4.9% degradation versus the single-user baseline, confirming that liboqs releases the Python GIL during C-level operations.
We introduce Coefficient of Variation (CoV) as a practical timing side-channel proxy across all FIPS 203/204 operations. ML-KEM-768 decapsulation achieves CoV = 3.9%, within the AES-256-GCM noise floor (2.1%). ML-DSA-65 signing shows CoV = 51.5%, expected from FIPS 204 rejection sampling, not a side-channel. This CoV methodology has not previously been applied to PQC library evaluation and provides a lightweight complement to formal constant-time verification tools. All results are reproducible via a single Docker command.
The August 2024 finalisation of FIPS 203 (ML-KEM), FIPS 204 (ML-DSA), and FIPS 205 (SLH-DSA) closed the algorithmic gap in post-quantum cryptography (PQC). The production gap -- hybrid combiners, versioned key formats, protocol helpers, and migration tooling -- remains open. We present quantum-safe, a Python library that closes all three critical gaps we identify, and a systematic evaluation of the nine-library ecosystem that quantifies them.
We score nine PQC libraries across eight production-readiness dimensions. Three dimensions have coverage below 35%: hybrid KEM support (11%), migration tooling (22%), and protocol integration (33%). quantum-safe scores Full on all eight. The full API reduces the hybrid KEM task from 45 lines of manual combiner code to three lines, directly lowering the risk of insecure combiner implementations.
We report the first statistically rigorous per-operation overhead measurement for a Python hybrid PQC library (3,000 iterations, CPU-pinned, bootstrapped 95% confidence intervals). A full X25519 + ML-KEM-768 handshake completes in 243 μs under Docker/Linux -- 0.5--2.5% of a typical TLS 1.3 round-trip budget. At 5,000 concurrent users, throughput holds at 2,848 ops/s with only 4.9% degradation versus the single-user baseline, confirming that liboqs releases the Python GIL during C-level operations.
We introduce Coefficient of Variation (CoV) as a practical timing side-channel proxy across all FIPS 203/204 operations. ML-KEM-768 decapsulation achieves CoV = 3.9%, within the AES-256-GCM noise floor (2.1%). ML-DSA-65 signing shows CoV = 51.5%, expected from FIPS 204 rejection sampling, not a side-channel. This CoV methodology has not previously been applied to PQC library evaluation and provides a lightweight complement to formal constant-time verification tools. All results are reproducible via a single Docker command.
The impending arrival of cryptographically relevant quantum computers (CRQCs) threatens the security foundations of modern software: Shor's algorithm breaks RSA, ECDSA, ECDH, and Diffie-Hellman, while Grover's algorithm reduces the effective security of symmetric and hash-based schemes. Despite NIST standardising post-quantum cryptography (PQC) in 2024 (FIPS 203 ML-KEM, FIPS 204 ML-DSA, FIPS 205 SLH-DSA), most codebases lack automated tooling to inventory classical cryptographic usage and prioritise migration based on quantum risk. We present Quantum-Safe Code Auditor, a quantum-aware static analysis framework that combines (i) regex-based detection of 15 classes of quantum-vulnerable primitives, (ii) LLM-assisted contextual enrichment to classify usage and severity, and (iii) risk scoring via a Variational Quantum Eigensolver (VQE) model implemented in Qiskit 2.x, incorporating qubit-cost estimates to prioritise findings. We evaluate the system across five open-source libraries -- python-rsa, python-ecdsa, python-jose, node-jsonwebtoken, and Bouncy Castle Java -- covering 5,775 findings. On a stratified sample of 602 labelled instances, we achieve 71.98% precision, 100% recall, and an F1 score of 83.71%. All code, data, and reproduction scripts are released as open-source.
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.
The accelerating development of large-scale quantum computers poses an existential threat to the public-key cryptographic infrastructure that underpins modern digital communication. Algorithms such as RSA and Elliptic Curve Cryptography (ECC), which currently secure internet traffic, digital signatures, and data-at-rest, are vulnerable to Shor's algorithm running on a sufficiently powerful quantum processor. In response, the U.S. National Institute of Standards and Technology (NIST) finalized the first post-quantum cryptography (PQC) standards in August 2024—FIPS 203 (ML-KEM/Kyber), FIPS 204 (ML-DSA/Dilithium), and FIPS 205 (SLH-DSA/SPHINCS+)—marking the beginning of a global migration toward quantum-resistant cryptography. This paper presents a hybrid C++/Python secure storage and communication platform (source code available at https://github.com/Sujithb128989/Quantum-Safe-Backend) that implements NIST-selected PQC algorithms in a production-oriented architecture. The backend employs CRYSTALS-Dilithium5 for quantum-resistant transport authentication, Kyber for key encapsulation, and AES-256-GCM for symmetric encryption-at-rest, delivered through a dual-stack gRPC/HTTP architecture containerized with Docker. We describe the system's design rationale, detail the cryptographic pipeline from certificate generation to atomic key rotation, and discuss the engineering challenges of integrating post-quantum primitives into real-world software systems.
The imminent threat of cryptographically relevant quantum computers (CRQCs) to RSA and elliptic curve cryptography — combined with the 'harvest now, decrypt later' attack paradigm — necessitates an urgent enterprise PKI migration to post quantum cryptographic (PQC) algorithms. This paper presents a comprehensive hybrid PKI framework enabling phased, backward compatible migration from classical to post quantum certificate chains. The framework embeds dual signatures (ECDSA + CRYSTALS Dilithium3) within X.509v3 certificates following the emerging RFC 9480 composite certificate standard. We provide Algorithm 2 (HybridCertIssue) specifying the complete certificate generation and verification protocol, and a migration roadmap structured across five phases from 2021 to 2035+. Experimental evaluation on a 10,000 node enterprise PKI demonstrates: TLS handshake overhead of +4.6 KB, latency increase of +38ms (LAN p50), and Dilithium3 signing throughput of 800 ops/sec on FIPS 140 3 HSMs. Security proofs establish that the hybrid scheme is secure if either the classical or PQC scheme is unforgeable — requiring an adversary to simultaneously break both ECDSA and Dilithium3. The migration cost model scales O(n log n) for n node PKI hierarchies. A 30 organization survey quantifies migration readiness: only 41% have completed cryptographic asset inventory, representing the critical first blocker.
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.
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.