This preprint presents a systematic review of how quantum computing impacts the security of classical cryptography and what mitigation strategies are available. The review synthesises key survey papers, standards reports and transition guidelines on post-quantum cryptography (PQC) and quantum-safe security published between 2015 and 2025. First, the paper summarises the impact of Shor’s and Grover’s algorithms on widely deployed public-key schemes, symmetric ciphers and hash functions, highlighting in particular the existential break of RSA, Diffie–Hellman and elliptic-curve cryptography, and the reduced security margins for symmetric and hash-based constructions. It then examines major quantum-resilient responses, including lattice-, code-, multivariate- and hash-based PQC, quantum key distribution (QKD), hybrid classical–PQC schemes and crypto-agile architectures. Building on Mosca’s x, y, z risk-timing model, the review discusses cross-cutting themes such as harvest-now-decrypt-later threats and sector-specific implications for government and defence, finance and blockchain, healthcare, cloud providers and critical infrastructure. It identifies several research gaps, including the lack of quantitative migration-cost data, limited coverage of small and resource-constrained organisations, and few system-scale evaluations comparing PQC-only, hybrid and QKD-based designs. The paper concludes by arguing that planning and investment in quantum-resilient cryptography need to start now, before migration time and data shelf-life push critical systems into the risky regime.
This preprint presents a systematic review of how quantum computing impacts the security of classical cryptography and what mitigation strategies are available. The review synthesises key survey papers, standards reports and transition guidelines on post-quantum cryptography (PQC) and quantum-safe security published between 2015 and 2025. First, the paper summarises the impact of Shor’s and Grover’s algorithms on widely deployed public-key schemes, symmetric ciphers and hash functions, highlighting in particular the existential break of RSA, Diffie–Hellman and elliptic-curve cryptography, and the reduced security margins for symmetric and hash-based constructions. It then examines major quantum-resilient responses, including lattice-, code-, multivariate- and hash-based PQC, quantum key distribution (QKD), hybrid classical–PQC schemes and crypto-agile architectures. Building on Mosca’s x, y, z risk-timing model, the review discusses cross-cutting themes such as harvest-now-decrypt-later threats and sector-specific implications for government and defence, finance and blockchain, healthcare, cloud providers and critical infrastructure. It identifies several research gaps, including the lack of quantitative migration-cost data, limited coverage of small and resource-constrained organisations, and few system-scale evaluations comparing PQC-only, hybrid and QKD-based designs. The paper concludes by arguing that planning and investment in quantum-resilient cryptography need to start now, before migration time and data shelf-life push critical systems into the risky regime.
With the arrival of fault-tolerant quantum computers, an existential threat has come to the cryptographic underpinnings of the security infrastructure in place for modern information technologies. Virtually all secure digital communication protocols used today are based on classical public-key cryptographic systems – RSA, Elliptic Curve Cryptography (ECC) and Diffie-Hellman key exchange – that are susceptible to polynomial-time quantum attacks using Shor's algorithm. Symmetric cryptographic algorithms that are not broken are being effectively halved by Grover's algorithm, for example, AES. In this article, a complete and journal-standard systematic review of quantum computing and its implications in the field of information technology security is presented which includes 22 peer-reviewed publications from 2023-2025. The study covers the basics of quantum computing (qubits, superposition, entanglement and quantum gates), and how quantum computing specifically poses a threat to classical cryptography via algorithmic mechanisms. The three post-quantum cryptographic algorithms that were standardised by the National Institute of Standards and Technology (NIST) in August 2024 (ML-KEM, FIPS 203; ML-DSA, FIPS 204; and SLH-DSA, FIPS 205) are compared based on their security assumptions, performance, and readiness for deployment. The practical limitations and the use of Quantum Key Distribution, (QKD), as a physics based alternative to the computational security assumptions are discussed. Results show that although mature PQ solutions are now available for most cryptographic applications, the migration challenge, including legacy system transitions, migration architecture, and governance, is significant and pressing as the ‘harvest now, decrypt later’ threat model is relevant and adversaries might be collecting encrypted data for quantum decryption. The impact for financial services, health care, government, cloud infrastructure and critical national infrastructure is discussed. Lastly, the researchers list key research areas: standardisation of quantum-safe protocols, hybrid PQC-QKD designs, light-weight PQC for constrained devices, and quantum-safe blockchain.
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 represents a paradigm shift that poses a profound threat to contemporary financial cryptographic systems. This study investigates the implications of quantum computing on classical encryption mechanisms and evaluates the effectiveness of post-quantum cryptographic solutions for securing financial transactions. Using a mixed-methods experimental approach, the study quantitatively analyzes the vulnerability of widely used cryptographic algorithms, including RSA, elliptic curve cryptography, and AES, under quantum attack models based on Shor’s and Grover’s algorithms. The results demonstrate a drastic reduction in security for asymmetric cryptographic schemes and a significant degradation in symmetric key strength, effectively halving their security margins. Qualitative risk analysis further reveals heightened exposure of financial systems to long-term data breaches, transaction manipulation, and regulatory non-compliance, particularly under “harvest-now, decrypt-later” scenarios. Post-quantum cryptographic schemes, including lattice-based and hash-based methods, are shown to provide robust resistance to quantum attacks while introducing manageable computational overhead. The findings highlight the importance of crypto-agility, hybrid cryptographic deployment, and early migration strategies to mitigate quantum-induced risks. This study concludes that the proactive adoption of quantum-safe cryptography is essential to preserving financial security, operational resilience, and trust in the emerging quantum era.
The rapid growth of quantum computing poses a critical threat to classical cryptographic systems. That is due in large part to the fact that they represent efficient solutions for some of the most challenging mathematical problems such as integer factoring or finding discrete logarithms. Schemes currently in wide use including RSA, Diffie–Hellman, and elliptic curve cryptography are particularly susceptible to being attacked by quantum computers, using algorithms like Shor's Algorithm and Grover's Algorithm. The advent of post-quantum cryptography (PQC) provides a promising potential answer to providing longterm security from adversaries using quantum computing capabilities. This paper presents a comprehensive state-of-the-art review of various PQC techniques currently being researched, including lattice-based methods, code-based methods, multivariate methods, hash-based methods, and isogeny-based methods. key challenges that will need to be addressed include computational overhead, large key sizes and implementation complexity. Furthermore the study reviews the current standardization efforts by the National Institute of Standards and Technology related to PQC and discusses some of the very specific practical considerations that need to be considered before widely deploying these techniques. The paper concludes by a complete list of existing research challenges and proposed future work that will assist in the development of efficient and scalable systems that will resist attacks from quantum computers.
The advent of large-scale quantum computers poses an existential threat to the cryptographic algorithms that underpin modern digital security. Shor's algorithm enables quantum computers to factor large integers and compute discrete logarithms in polynomial time, rendering RSA, Elliptic Curve Cryptography (ECC), and Diffie-Hellman key exchange fundamentally insecure. Meanwhile, Grover's algorithm provides a quadratic speedup for brute-force search, effectively halving the security strength of symmetric ciphers and hash functions. This paper presents a comprehensive investigation into the impact of quantum computing on both asymmetric and symmetric cryptographic algorithms. We analyze the computational resources required by quantum attacks on current standards, evaluate the timeline of quantum threats based on hardware roadmaps from leading quantum computing companies, and conduct a systematic performance comparison of NIST-standardized post-quantum cryptographic (PQC) algorithms. Our experimental evaluation covers key generation time, encapsulation/decapsulation latency, signature generation/verification speed, key sizes, and bandwidth overhead across lattice-based, code-based, hash-based, and multivariate cryptographic schemes. Results indicate that lattice-based schemes, particularly CRYSTALS-Kyber and CRYSTALS-Dilithium, offer the most favorable balance of security and performance for practical deployment. We also propose a phased migration framework for transitioning existing cryptographic infrastructure to quantum-resistant alternatives, addressing compatibility, performance, and operational challenges.
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.