The advent of quantum computing poses significant threats to classical public-key cryptographic primitives such as RSA and elliptic-curve cryptography. As many critical network and security protocols depend on these primitives for key exchange and authentication, there is an urgent need to understand their quantum vulnerability and assess the progress made towards integrating post-quantum cryptography (PQC). This survey provides a detailed examination of nine widely deployed protocols - TLS, IPsec, BGP, DNSSEC, SSH, QUIC, OpenID Connect, OpenVPN, and Signal Protocol - analysing their cryptographic foundations, quantum risks, and the current state of PQC migration. We find that TLS and Signal lead the transition with hybrid post-quantum key exchange already deployed at scale, while IPsec and SSH have standardised mechanisms but lack widespread production adoption. DNSSEC and BGP face the most significant structural barriers, as post-quantum signature sizes conflict with fundamental protocol constraints. Across all protocols, key exchange proves consistently easier to migrate than authentication, and protocol-level limitations such as message size and fragmentation often dominate over raw algorithm performance. We also discuss experimental deployments and emerging standards that are shaping the path towards a quantum-resistant communication infrastructure.
The advent of quantum computing poses significant threats to classical public-key cryptographic primitives such as RSA and elliptic-curve cryptography. As many critical network and security protocols depend on these primitives for key exchange and authentication, there is an urgent need to understand their quantum vulnerability and assess the progress made towards integrating post-quantum cryptography (PQC). This survey provides a detailed examination of nine widely deployed protocols - TLS, IPsec, BGP, DNSSEC, SSH, QUIC, OpenID Connect, OpenVPN, and Signal Protocol - analysing their cryptographic foundations, quantum risks, and the current state of PQC migration. We find that TLS and Signal lead the transition with hybrid post-quantum key exchange already deployed at scale, while IPsec and SSH have standardised mechanisms but lack widespread production adoption. DNSSEC and BGP face the most significant structural barriers, as post-quantum signature sizes conflict with fundamental protocol constraints. Across all protocols, key exchange proves consistently easier to migrate than authentication, and protocol-level limitations such as message size and fragmentation often dominate over raw algorithm performance. We also discuss experimental deployments and emerging standards that are shaping the path towards a quantum-resistant communication infrastructure.
The emergence of quantum computing presents a fundamental challenge to the security of current Internet communication systems. Transport Layer Security (TLS), which forms the backbone of secure web communication, predominantly relies on classical public-key cryptographic algorithms such as RSA and elliptic curve cryptography (ECC), both of which are susceptible to quantum attacks. This paper conducts a large scale empirical evaluation of post-quantum readiness across 32,011 domains, with a primary focus on real-world TLS deployments across diverse sectors by analysing negotiated TLS parameters, including protocol versions, cipher suites, key exchange mechanisms, and certificates. The results indicate that while modern protocols like TLS 1.3 and QUIC are gaining adoption, 15.70% of domains especially in critical sectors such as banking and government still rely on TLS 1.2. Furthermore, 49.3% of domains support hybrid post-quantum key exchange mechanisms (e.g., MLKEM768 with X25519), whereas 50.7% continue to use classical key exchange, reflecting partial transition. Notably, 0% adoption of hybrid post-quantum certificates was observed, leaving the authentication layer vulnerable to quantum-enabled attacks such as certificate forgery. The findings reveal uneven adoption of post-quantum mechanisms across sectors, where technology driven platforms are advancing more rapidly than legacy-dependent infrastructures. Overall, the study highlights that achieving complete quantum resilience requires a coordinated transition not only in key exchange mechanisms but also in certificate infrastructures. Without such comprehensive migration, Internet communication systems remain vulnerable to long-term threats, including Harvest-Now-Decrypt-Later (HNDL) attacks.
The threats are existential to the traditional cryptosystems of public keys, including RSA, Diffie-Hellman, and elliptic curve cryptography (ECC), due to the rapid progress in quantum computing. Such algorithms as the Shor and Grover algorithms prove that as soon as large scale quantum computers are achieved, these classical cryptographic protocols will not provide any privacy and integrity to online communication. This has created an emergency to find post-quantum cryptography (PQC), or quantum-safe cryptography, which will resist attacks by both classical and quantum attackers. The paper is a review of the latest research and development in post-quantum cryptographic algorithms and their implementation in current security systems. We organize quantum-safe methods into significant organizations such as lattice-based, hash-based, multivariate polynomial-based and code-based encrypted communications. Each type has been evaluated critically based on computational efficiency, key sizes, speed of encryption/decryption and security proofs. The survey also examines the current standardization activities happening in the world and especially the U.S. National Institute of Standards and Technology (NIST) PQC competition, which lists candidate algorithms that have advanced to standard adoption. Besides this, the paper addresses hybrid cryptographic designs that use both classical and post-quantum bases in ensuring a seamless migration in the transition phase. Internet security protocols like TLS, VPNs and blockchain consensus as applications of PQC are examined in detail. Lastly, we pinpoint open research issues, which include creating lightweight PQC to support resource-constrained IoT devices, balancing performance and strong security assurances, and interoperability between the new PQC algorithms and existing infrastructures. Through detailed survey we inform the future of researchers, practitioners, and policymakers on the preparation of the post-quantum era of secure digital communications.
This thesis investigates the current state of Post-quantum cryptography (PQC) in the industry, with a particular focus on its practical deployment, integration challenges, and performance implications.The study combines a structured analysis of academic literature, standardization efforts, and industry guidance with an experimental evaluation of PQC integration in widely used security protocols. The analysis shows that, while significant progress has been made in the standardization of quantum-resistant algorithms such as ML-KEM, ML-DSA, and SLH-DSA, real-world adoption remains in an early and transitional phase. Organizations primarily focus on evaluation and pilot implementations, as deployment is constrained by interoperability issues, implementation maturity, and the complexity of migrating existing cryptographic infrastructures.To complement the conceptual analysis, experimental measurements were conducted for TLS, SSH, and IPsec to evaluate the performance impact of hybrid post-quantum cryptographic mechanisms. The results indicate that performance overhead is not uniform across components. In particular, post-quantum signature schemes introduce significant computational and network overhead, mainly due to increased key and certificate sizes. In contrast, hybrid key exchange mechanisms show only moderate performance impact across all evaluated protocols.The findings highlight that the primary challenge of PQC adoption lies not in algorithm design but in practical integration and large-scale migration. Hybrid cryptographic approaches emerge as the most viable strategy for enabling a gradual transition, balancing improved security against quantum threats with operational feasibility.Overall, this thesis demonstrates that PQC is transitioning from a theoretical research field to a practical engineering challenge, with significant implications for the future design of secure communication systems.
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.
Abstract The prospect of cryptanalytically relevant quantum computers (CRQCs) motivates a transition from classical cryptography to post-quantum cryptography (PQC). Shor’s algorithm threatens widely deployed public-key schemes used for key establishment and digital signatures, while Grover’s algorithm reduces effective security margins for symmetric-key and hash-based primitives. The harvest-now, decrypt-later (HNDL) threat further increases urgency because adversaries can store encrypted data today for future decryption, placing long-lived confidentiality requirements and trust infrastructure at risk. This survey frames PQC adoption as a standards-to-deployment program. We review the PQC design space and summarize deployment-critical constraints, including handshake and certificate size growth, latency under network loss, computational cost, memory and storage requirements, implementation complexity, and side-channel robustness. We then present an iterative migration pipeline covering cryptographic inventory, risk-based prioritization using data sensitivity and cryptoperiod, algorithm and parameter profile selection, hybrid classical and PQC constructions for backward compatibility, pilot validation with measurable go/no-go criteria, and long-term operations with crypto-agility. Finally, we connect standardization outputs to concrete integration surfaces and illustrate the workflow across transport layer security (TLS) and the web public key infrastructure (Web PKI), virtual private networks (VPNs) and internet protocol security (IPsec), and constrained Internet of things (IoT) deployments, and we summarize open challenges in interoperability, public key infrastructure (PKI) transition mechanics, implementation maturity and operational governance.
The advent of quantum computing has precipitated an estimated attack resistant cryptography system necessitating quantum attacks. The classical asymmetric algorithms, i.e., RSA and ECC are susceptible to Shor algorithm and a transition should be made to Post-Quantum Cryptography (PQC) anymore. The novelty of this work lies in providing a unified comparative framework that analyzes PQC families through security assumptions, concrete key/ciphertext sizes, and implementation complexity an aspect not addressed collectively in prior surveys. This survey gives a general picture of the status of the design process and general evaluation of PQC accounting its application within the paradigm of the diversified networks including the IoT and 5G/6G and in the cyber-physical environment. Furthermore, this review uniquely synthesizes practical hybrid‑deployment strategies, including protocol layering, coexistence models, and backward‑compatibility mechanisms, offering actionable guidance for real‑world migration. Additionally, the manuscript contributes a prioritized list of open problems across IoT, 5G/6G, blockchain, and cyber‑physical systems, highlighting domains facing the most urgent quantum‑resilience challenges. In this paper, the authors will evaluate the most popular PQC schemes, including schemes based on lattice, code, hash, and isogeny, depending on their performance, scalability, and interoperability (with reference to the recent research). It also examines the problems of integration as implemented with respect to the computational overhead, latency and adoption of hybrid with classical cryptography. This is expounded more to the standardization of PQC by NISTs and with a focus on such algorithms as CRYSTALS-Kyber and Dilithium. The findings suggest that, hybrid PQC protocols are able to control quantum resistance and actual performance in numerous infrastructures in computing systems.