This paper provides a comprehensive review of quantum readiness as a critical, multidimensional framework for navigating the upcoming quantum computing era. It addresses the imminent threat posed by cryptographically relevant quantum computers (CRQCs), which will be capable of breaking the public-key cryptographic systems (like RSA and ECC) that currently secure digital communications and e-commerce. The concept of ”harvest now, decrypt later” (HNDL), where adversaries collect encrypted data today to decrypt it once quantum computers are available, highlights the urgency of this transition. The review is structured around three key dimensions: the theoretical foundations of post-quantum cryptography (PQC), global standardization efforts, and real-world sectoral implementations. It discusses how quantum algorithms, specifically Shor’s and Grover’s algorithms, can render classical cryptography obsolete, and it analyzes the NIST Post-Quantum Cryptography Standardization Project, which has selected the first-generation PQC standards. The paper also examines strategies from the European Union and other nations, noting the geopolitical implications of standards fragmentation. Furthermore, the review explores the practical adoption of PQC in critical sectors like finance, telecommunications, and defense, emphasizing the importance of crypto-agility—the ability to rapidly switch cryptographic algorithms—for future-proofing systems. It also highlights open challenges, including performance overheads, legacy system migration, and the shortage of skilled professionals. The paper concludes by outlining future directions for a secure transition, advocating for continuous research, global collaboration, and sustained investment to build a quantum-resilient digital ecosystem.
This paper provides a comprehensive review of quantum readiness as a critical, multidimensional framework for navigating the upcoming quantum computing era. It addresses the imminent threat posed by cryptographically relevant quantum computers (CRQCs), which will be capable of breaking the public-key cryptographic systems (like RSA and ECC) that currently secure digital communications and e-commerce. The concept of ”harvest now, decrypt later” (HNDL), where adversaries collect encrypted data today to decrypt it once quantum computers are available, highlights the urgency of this transition. The review is structured around three key dimensions: the theoretical foundations of post-quantum cryptography (PQC), global standardization efforts, and real-world sectoral implementations. It discusses how quantum algorithms, specifically Shor’s and Grover’s algorithms, can render classical cryptography obsolete, and it analyzes the NIST Post-Quantum Cryptography Standardization Project, which has selected the first-generation PQC standards. The paper also examines strategies from the European Union and other nations, noting the geopolitical implications of standards fragmentation. Furthermore, the review explores the practical adoption of PQC in critical sectors like finance, telecommunications, and defense, emphasizing the importance of crypto-agility—the ability to rapidly switch cryptographic algorithms—for future-proofing systems. It also highlights open challenges, including performance overheads, legacy system migration, and the shortage of skilled professionals. The paper concludes by outlining future directions for a secure transition, advocating for continuous research, global collaboration, and sustained investment to build a quantum-resilient digital ecosystem.
Quantum computing poses an existential threat to public-key cryptography, with Shor's algorithm capable of breaking RSA and elliptic curve systems once cryptographically relevant quantum computers (CRQCs) emerge. While post-quantum cryptography (PQC) offers algorithmic solutions, organizational readiness extends beyond technical implementation to encompass governance, interoperability, and adaptive capacity. This review synthesizes the quantum threat landscape, evaluates NIST-standardized PQC algorithms through quantitative performance analysis, and examines global standardization dynamics. We introduce a novel Quantum Readiness Maturity Model (QRMM) that enables organizations to assess and advance their preparedness across five dimensions: cryptographic infrastructure, governance frameworks, sectoral adaptation, interoperability resilience, and strategic agility. Applying this model to finance, telecommunications, and defense sectors reveals systematic gaps in migration planning and crypto-agility. Our analysis demonstrates that quantum readiness requires treating cryptographic transformation as a strategic enterprise capability rather than a purely technical upgrade. The proposed framework provides actionable pathways for practitioners while identifying critical research directions in hybrid deployment strategies, post-quantum PKI architectures, and algorithmic diversity.
The accelerating development of quantum computing represents one of the most significant paradigm shifts in the history of information security. Cryptographic systems that currently underpin global digital infrastructure—including RSA, Diffie–Hellman, and Elliptic Curve Cryptography—rely on mathematical assumptions that collapse under quantum algorithms such as Shor’s and Grover’s. Post-Quantum Cryptography (PQC) emerges as the most viable and immediate solution to secure communications in the quantum era, offering cryptographic primitives that can be deployed on today’s classical hardware while resisting both classical and quantum attacks. This review provides a comprehensive, detailed examination of PQC, analyzing its mathematical foundations, algorithmic families, standardization progress, and deployment challenges. Special emphasis is placed on the NIST PQC standardization process, the risk posed by “harvest-now-decrypt-later” adversaries, the complexities of global cryptographic migration, and the implications for critical digital infrastructures such as cloud computing, blockchain systems, long-lifespan data archives, IoT ecosystems, and national cybersecurity. Through standalone equations, tables, and figures—including a conceptual visual provided by the user—this paper offers a complete, cohesive, and rigorous synthesis. The findings underscore that the transition to PQC is not optional but imperative, requiring coordinated scientific, governmental, and industrial effort to safeguard the digital future.
India's digital governance infrastructure, spanning Aadhaar, UPI, DigiLocker, and critical sectors such as defence, finance, and telecommunications, is built upon classical publickey cryptography (RSA, ECC). The emergence of fault-tolerant quantum computers threatens to dismantle these foundations through Shor's algorithm, which solves integer factorisation and discrete logarithm problems in polynomial time, while Grover's algorithm reduces symmetric key security. The "harvest now, decrypt later" strategy magnifies the urgency, as adversaries can store encrypted data today for future decryption. This paper provides a comprehensive analysis of the post-quantum cryptography (PQC) migration imperative for India. We examine the quantum threat landscape, review candidate PQC families (lattice-, code-, multivariate-, hash-, and isogeny-based) and the newly standardised NIST algorithms, and detail the technical, regulatory, and economic challenges of large-scale PQC adoption in India's heterogeneous e-governance ecosystem. A phased implementation roadmap aligned with the National Quantum Mission (2026 to 2035) is presented, prioritising critical sectors (defence, banking, telecom, Aadhaar/UPI). The paper further highlights strategic opportunities for indigenous capability building, global certification leadership, and the reinforcement of digital sovereignty. By synthesising official reports, international standards, and sector-specific requirements, this work offers actionable guidance for transitioning India's governance to a quantum-resilient future. The paper further proposes the Quantum Governance Readiness and Infrastructure Decision Framework (Q-GRID), an India-specific, measurable decision framework that integrates quantum exposure, data longevity, systemic criticality, dependency, migration complexity, and regulatory urgency into a composite Quantum Risk Index to prioritise migration actions.
The cybersecurity infrastructure of the digital age is facing an unprecedented threat with the rise of quantum computing. Current public-key cryptographic systems are at risk of being broken by quantum algorithms such as Shor’s and Grover’s. This threat has triggered a global effort, known as quantum readiness, which necessitates a proactive approach in both academia and the industry. This review article examines the fundamental dynamics of quantum readiness, academic research worldwide, and concrete applications in the cybersecurity sector. The article details the international competition led by the National Institute of Standards and Technology (NIST) to define post-quantum cryptography (PQC) standards. It also analyzes the national PQC strategies of the US, the EU, China, and other Western countries, the transition processes in critical sectors like finance and telecommunications, and key concepts like crypto-agility. This study reveals that the quantum threat is not merely a theoretical possibility but a strategic security issue, and that preparing for this threat is vital for a seamless digital security future.
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.
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.