This paper surveys the practical transition from conventional to post-quantum/quantum-safe cryptography (PQC) across contemporary infrastructures. Large-scale quantum computers impact cryptographic primitives differently: conventional asymmetric encryption/signatures will become insecure, while symmetric ciphers largely remain viable and hash functions face only modest weakening. Therefore, adaptations to existing as well as future systems are needed. Depending on the application area, “harvest-now, decrypt-later” may either be a real threat or not, so urgent action is required only in those areas, where once security has been broken it cannot be reconstructed, while others may have more time to adapt (e.g. where data has a very short lifetime anyway). The paper discusses a long list of potentially affected systems, and what special challenges implementing postquantum cryptography poses for them, and where upgrading needs to be prioritized. A problem identified as remaining unsolved is “grandfathering”: what to do with devices that simply cannot be updated, e.g. because the cryptography is integrated into their hardware.
This paper surveys the practical transition from conventional to post-quantum/quantum-safe cryptography (PQC) across contemporary infrastructures. Large-scale quantum computers impact cryptographic primitives differently: conventional asymmetric encryption/signatures will become insecure, while symmetric ciphers largely remain viable and hash functions face only modest weakening. Therefore, adaptations to existing as well as future systems are needed. Depending on the application area, “harvest-now, decrypt-later” may either be a real threat or not, so urgent action is required only in those areas, where once security has been broken it cannot be reconstructed, while others may have more time to adapt (e.g. where data has a very short lifetime anyway). The paper discusses a long list of potentially affected systems, and what special challenges implementing postquantum cryptography poses for them, and where upgrading needs to be prioritized. A problem identified as remaining unsolved is “grandfathering”: what to do with devices that simply cannot be updated, e.g. because the cryptography is integrated into their hardware.
The advent of quantum computing poses a paradigm-shifting threat to classical cryptographic systems that underpin global digital security. As quantum processors advance towards practical scalability, previously secure encryption schemesparticularly those based on integer factorization (e.g., RSA) and discrete logarithm problems (e.g., ECC and DH)-are rendered vulnerable due to quantum algorithms like Shor's and Grover's. This paper critically examines the implications of quantum computing for contemporary cryptographic frameworks and explores the urgent need to transition toward quantum-resistant alternatives. We begin by analyzing the computational capabilities of quantum systems and their impact on symmetric and asymmetric cryptographic algorithms. The study delves into the principles of postquantum cryptography (PQC), including lattice-based, hash-based, code-based, multivariate polynomial, and supersingular isogeny cryptography, evaluating their strengths, implementation challenges, and resistance to quantum attacks. Additionally, we assess ongoing global initiatives such as NIST's post-quantum cryptography standardization project, highlighting their role in shaping future security infrastructures. The paper also considers hybrid cryptographic models and quantum key distribution (QKD) as transitional and long-term security strategies. By rethinking security from both theoretical and practical standpoints, this study emphasizes the need for immediate and collaborative action across academia, industry, and government sectors to future-proof digital communication systems against the looming quantum threat.
Current cryptographic systems, heavily reliant on classical algorithms, are increasingly vulnerable to the formidable capabilities of quantum computing. Notably, quantum algorithms such as Shor’s and Grover’s pose profound threats by accelerating decryption processes, which could soon make existing cryptosystems ineffective. This paper stresses the critical need and complexity of shifting to Post-Quantum Cryptography (PQC) to safeguard encrypted communications against these emerging quantum threats. It outlines the timeline of the National Institute of Standards and Technology’s (NIST) efforts in standardizing PQC, elucidating the significant challenges and the essential nature of adopting these new standards. While NIST provides structured guidance, transitioning to PQC presents substantial risks and difficulties, particularly in terms of organizational adaptation and the technical overhaul required. The discourse further explores the tangible implications of quantum advancements on both symmetric and asymmetric key cryptography, highlighting the potential vulnerabilities and the increased risk of security breaches. The paper underscores the imperative for immediate action in initiating the transition towards robust PQC systems, given the rapid development and anticipated deployment of quantum computing technologies capable of decrypting currently secure information. This transition is not merely a technical upgrade but a crucial strategic move to preemptively counteract quantum threats, ensuring the continued confidentiality and integrity of sensitive data across various sectors.
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.
The imminent emergence of quantum computers poses unprecedented challenges to the current cryptographic standards that secure vital digital communications and data worldwide. This paper addresses the vulnerabilities of existing cryptographic systems susceptible to quantum-based attacks and emphasizes a dedicated transition plan to post-quantum cryptography (PQC). We first examine the current state of cryptographic practices, highlight the quantum threat, and present the framework and need for PQC. In addition, a comprehensive strategy is presented that encompasses the identification, protection, detection, response, and recovery phases and integrates PQC into existing security infrastructures, specifically the Cybersecurity Framework Version 2.0 of the National Institute of Standards and Technology (NIST). Methods and technologies discussed include the development of robust PQC algorithms, tools for their large-scale implementation, and hybrid cryptographic systems that combine traditional and quantum-resistant techniques. Practical implementations on various hardware and software platforms are also presented in case studies that provide real-world insight into the challenges and innovations in using PQC. We conclude with a discussion of hybrid approaches, regulatory considerations, and recommendations derived from early adopters to guide future efforts to create a quantum-resilient digital landscape.
Quantum computing offers major computational advances but threatens modern public-key cryptography. Classical algorithms such as RSA, Diffie–Hellman (DH), and Elliptic Curve Cryptography (ECC) are vulnerable to quantum attacks, particularly Shor’s algorithm. As large-scale quantum capabilities emerge, post-quantum cryptography (PQC) has become essential to ensure future data confidentiality, integrity, and authentication. This paper discusses the need to replace classical cryptography, explores quantum-safe solutions, and examines challenges in large-scale migration. PQC is critical across government, critical infrastructure, finance, healthcare, telecommunications, IoT, autonomous vehicles, and 6G networks. A key concern is “harvest-now, decrypt-later” attacks, where encrypted data is stored today for future quantum decryption. The study analyzes classical cryptographic vulnerabilities and reviews major PQC families: lattice-based, hash-based, code-based, multivariate-based, and isogeny-based schemes, highlighting the ongoing NIST standardization efforts. It proposes a migration framework including quantum-readiness assessment, algorithm selection, hybrid implementation, and performance evaluation. Results show that although PQC introduces higher computational complexity, optimized implementations can support real-time applications with reasonable overhead. Among PQC approaches, lattice-based schemes appear most mature and balanced in terms of security and key size. The paper concludes that quantum-safe cryptography is a necessary evolution requiring continuous monitoring, adaptable systems, and alignment with emerging standards.
Quantum computing poses a significant threat to existing cryptosystems, as Shor's and Grover's algorithms efficiently solve the underlying mathematical problems of classical cryptographic algorithms. Post-Quantum Cryptography (PQC) provides a proactive response to this emerging threat, enabling resilience against quantum attacks. Researchers have extensively explored various mathematical structures believed to be resilient against quantum attacks across several PQC families. The NIST PQC standardisation project demonstrates the global need to integrate PQC into existing digital systems, even before the quantum era. Practical use cases of PQC schemes in various areas, along with the associated challenges, have been thoroughly studied to understand future research directions that must be followed for the better optimisation of real-world PQC implementation in a quantum-safe future.