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.
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.
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.
The prospect of cryptographically relevant quantum computers threatens public-key primitives underpinning modern digital infrastructure, including RSA, Diffie-Hellman, and elliptic-curve cryptography. Post-quantum cryptography (PQC) responds with algorithms believed to be hard for both classical and quantum adversaries. In August 2024, the U.S. National Institute of Standards and Technology (NIST) finalised the first three PQC standards: FIPS 203 (ML-KEM, based on Kyber), FIPS 204 (ML-DSA, based on Dilithium), and FIPS 205 (SLH-DSA, based on SPHINCS+). This paper surveys the algorithmic families behind these standards, the harvest-now-decrypt-later threat model, hybrid migration strategies, performance trade-offs, and the engineering challenges of transitioning the global cryptographic stack. We examine deployment progress in TLS, SSH, X.509, and constrained devices, and outline open research questions on side-channel security, falcon-style signatures, and the long-term replacement schedule for classical asymmetric cryptography.
The impressively fast development of quantum computing is a serious threat to classical public-key cryptography, and algorithms such as Shor's and Grover's will render RSA and elliptic curve systems essentially useless as soon as a cryptanalytically relevant quantum computer becomes available. Although it is still some way off before such machines are available, the harvest-now-encrypt-later threat highlights the need for proactive defense. In response, the National Institute of Standards and Technology (NIST) published the first post-quantum cryptography standards in 2024, including ML-KEM (Kyber) for key establishment, ML-DSA (Dilithium) for digital signatures and SLH-DSA (SPHINCS+) as a stateless hash-based alternative. This paper is a summary of the evolving post-quantum landscape, starting with the standards and their underlying security and then moving on to migration policies such as CNSA 2.0 and CISA, NSA and NIST guidance. It also looks at integration patterns for important protocols such as TLS, IPsec, SSH, and code signing. A performance, interoperability and overhead evaluation methodology is presented with results showing that hybrid deployment and crypto-agile architectures make PQC adoption a viable option. The paper concludes by providing a governance-oriented roadmap, where inventory, prioritization and pilot deployments are identified as near-term actions, with open questions remaining on performance optimization, implementation security and algorithm resilience over time.
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.
Purpose: The purpose of this paper is to examine the emerging threat that large-scale quantum computing poses to classical public-key cryptographic systems, particularly RSA and Elliptic Curve Cryptography (ECC), which form the backbone of contemporary digital security infrastructures. In response to this threat, the study aims to analyze post-quantum cryptography (PQC) as a viable long-term solution capable of resisting both classical and quantum adversaries. The paper further seeks to assess the urgency of PQC adoption in light of the “harvest now, decrypt later” threat model and to evaluate the practical readiness of quantum-safe cryptographic algorithms currently under consideration by the National Institute of Standards and Technology (NIST). Materials and Methods: This study employs a qualitative and analytical research methodology grounded in an extensive review of authoritative sources, including NIST’s post-quantum cryptography standardization documents, recent academic literature, industry white papers, and policy reports from organizations such as RAND Corporation and Cloudflare. The analysis systematically surveys major families of post-quantum cryptographic algorithms namely lattice-based, code-based, and hash-based schemes and evaluates them based on security assumptions, computational efficiency, implementation complexity, and standardization maturity. Findings: The analysis indicates that Lattice-based cryptographic schemes demonstrate the highest maturity and practical readiness, evidenced by their selection in NIST’s PQC process. Code- and hash-based methods provide strong security but face key size and performance challenges. The lack of scalable quantum computers does not reduce urgency, as data harvesting persists. Artificial intelligence emerges as a key enabler for accelerating PQC adoption. Unique Contribution to Theory, Practice and Policy: The paper recommends a proactive, phased post-quantum migration using hybrid cryptographic architectures. Organizations should conduct inventories, benchmarking, and pilot deployments aligned with NIST standards. AI-driven tools are advised to improve key management and reduce complexity. Continued interdisciplinary research and policy support are encouraged to ensure a secure, scalable transition to quantum-resistant security systems.
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.