The arrival of cryptographically relevant quantum computers (CRQCs) represents an existential threat to the public-key cryptographic infrastructure underpinning global enterprise operations. Enterprise security today relies on RSA and elliptic-curve cryptography (ECC) for TLS, VPNs, PKI, code signing, and identity systems—all of which are fundamentally broken by Shor's algorithm on a sufficiently powerful quantum computer. The defining risk is time-shifted compromise: adversaries can harvest encrypted traffic today and decrypt it once CRQCs exist, a threat already underway according to U.S. intelligence assessments. NIST finalized three post-quantum cryptographic (PQC) standards in August 2024 (FIPS 203/204/205) and mandates deprecation of quantum-vulnerable algorithms by 2035. Yet only 5% of organizations have implemented quantum-safe encryption and 95% lack formal quantum transition plans. This paper provides a comprehensive, threat-driven analysis across seven dimensions: quantum algorithm impact, harvest-now-decrypt-later (HNDL) threat models, enterprise asset risks (PKI, TLS, VPNs, code signing, cloud, IoT, identity, blockchain, supply chain), sector-specific vulnerabilities (financial services, healthcare, critical infrastructure), cryptographic primitive analysis, migration standards and roadmaps, and enterprise readiness gaps. The convergence of HNDL attacks already underway, multi-decade data sensitivity windows, and 12–15 year enterprise migration timelines means the migration deadline has, for most sectors, already passed.
The arrival of cryptographically relevant quantum computers (CRQCs) represents an existential threat to the public-key cryptographic infrastructure underpinning global enterprise operations. Enterprise security today relies on RSA and elliptic-curve cryptography (ECC) for TLS, VPNs, PKI, code signing, and identity systems—all of which are fundamentally broken by Shor's algorithm on a sufficiently powerful quantum computer. The defining risk is time-shifted compromise: adversaries can harvest encrypted traffic today and decrypt it once CRQCs exist, a threat already underway according to U.S. intelligence assessments. NIST finalized three post-quantum cryptographic (PQC) standards in August 2024 (FIPS 203/204/205) and mandates deprecation of quantum-vulnerable algorithms by 2035. Yet only 5% of organizations have implemented quantum-safe encryption and 95% lack formal quantum transition plans. This paper provides a comprehensive, threat-driven analysis across seven dimensions: quantum algorithm impact, harvest-now-decrypt-later (HNDL) threat models, enterprise asset risks (PKI, TLS, VPNs, code signing, cloud, IoT, identity, blockchain, supply chain), sector-specific vulnerabilities (financial services, healthcare, critical infrastructure), cryptographic primitive analysis, migration standards and roadmaps, and enterprise readiness gaps. The convergence of HNDL attacks already underway, multi-decade data sensitivity windows, and 12–15 year enterprise migration timelines means the migration deadline has, for most sectors, already passed.
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.
As the era of quantum computing approaches, the fundamental cryptographic primitives securing global communications face a paradigm shift. With the National Institute of Standards and Technology (NIST) finalizing new standards, the industry must urgently address the vulnerabilities of legacy systems. The imminent advent of CRQCs (Cryptographically Relevant Quantum Computers) poses an existential threat to the Public Key Infrastructure (PKI) underpinning the global digital economy. Classical algorithms such as RSA and ECC (Elliptic Curve Cryptography) are vulnerable to polynomial-time cryptanalysis via Shor’s algorithm. This study investigates the HNDL (Harvest Now, Decrypt Later) threat model and evaluates the resilience of NIST-standardized PQC (Post-Quantum Cryptography) algorithms: ML-KEM and ML-DSA. Utilizing a high-performance Fortinet networking environment, we experimentally validate that "Hybrid Mode" IPsec VPNs can achieve quantum resistance with negligible performance degradation, offering a viable migration path for enterprise infrastructure. Specifically, we benchmark the trade-offs between PQC’s larger key sizes and network latency, demonstrating that the overhead remains within acceptable operational thresholds. Implementing hybrid protocols provides a critical transition mechanism, allowing organizations to secure long-term data confidentiality against retrospective decryption while preserving interoperability with legacy systems.
Abstract—The advent of fault-tolerant Cryptanalytically Relevant Quantum Computers (CRQCs) presents an existential threat to modern information security. Shor's polynomial-time quantum algorithm renders widely deployed public-key cryptographic primitives—including RSA, Diffie-Hellman (DH), and Elliptic Curve Cryptography (ECDH/ECDSA)—completely vulnerable to private key derivation. Furthermore, 'Harvest Now, Decrypt Later' (HNDL) adversarial campaigns actively intercept and store encrypted enterprise telemetry today, anticipating future quantum decryption capabilities. In response, the National Institute of Standards and Technology (NIST) finalized its primary Post-Quantum Cryptography (PQC) standards in FIPS 203 (ML-KEM), FIPS 204 (ML-DSA), and FIPS 205 (SLH-DSA). However, transitioning complex enterprise IT ecosystems to quantum-resistant primitives introduces severe architectural and computational disruptions: public key and signature sizes increase by several orders of magnitude, cryptographic handshake latencies escalate, network packets experience Maximum Transmission Unit (MTU) fragmentation, and legacy Hardware Security Modules (HSMs) lack microarchitectural support for lattice-based polynomial arithmetic. This paper provides an exhaustive, mathematically grounded technical survey and architectural roadmap for enterprise PQC migration. We formalize the Module Learning with Errors (M-LWE) and Module Short Integer Solution (M-SIS) hardness foundations, evaluate hybrid classical/post-quantum cryptographic transition models across standard transport protocols (TLS 1.3, IKEv2/IPsec, SSH), and formulate an enterprise Crypto-Agility Maturity Model. Furthermore, we construct an empirical enterprise testbed measuring throughput, connection establishment latency, memory footprints, and packet fragmentation across legacy and quantum-resistant suites. Our results show that while ML-KEM-768 achieves microsecond-level encapsulation, its 1,088-byte ciphertext expands TLS ClientHello payloads into multiple TCP segments under constrained networks. Finally, we establish open research directions in post-quantum identity federations, stateful hash signature tracking, and hardware-accelerated polynomial arithmetic. Index Terms—Post-Quantum Cryptography (PQC), FIPS 203 (ML-KEM), FIPS 204 (ML-DSA), Crypto-Agility, TLS 1.3, Lattice-Based Cryptography, Harvest Now Decrypt Later, Hardware Security Modules (HSM), Enterprise Migration.
Abstract Cryptographically relevant quantum computers (CRQCs) would break widely deployed public-key cryptography (RSA/ECC) via Shor’s algorithm, enabling retroactive decryption of captured ciphertext (“harvest now, decrypt later”). This paper presents an enterprise-cloud transition framework that couples (i) standards-based algorithm selection using NIST’s post-quantum standards (FIPS 203–205), (ii) a cloud threat model that distinguishes retroactive confidentiality loss from forward integrity/authentication risks, and (iii) a quantitative timing-risk model grounded in Mosca’s inequality. Using a public expert-elicitation distribution for Q-day timing and a reproducible Monte Carlo estimator, we compare migration strategies and key planning parameters (migration start year, migration duration, and confidentiality lifetime). We also contrast this probabilistic view with common deterministic single-date Q-day planning, highlighting how tail uncertainty can materially change exposure estimates and recommended start years. For a representative enterprise case ( X=10 X = 10 years, Y=6 Y = 6 years), delaying the migration start from 2026 to 2030 increases the expected exposed fraction of the confidentiality window from 0.37 to 0.54 under a midline timeline. We also provide cloud-specific implementation guidance (crypto inventory, hybrid TLS/QUIC and service-mesh deployments, PKI readiness, and governance), and summarize performance and interoperability drivers arising from larger post-quantum key material.
Large-scale quantum computers threaten the public-key cryptography that protects enterprise data, communications, and digital identity. Shor's algorithm solves integer factorization and discrete logarithms in polynomial time, which would break RSA, Diffie-Hellman, and elliptic-curve schemes once a cryptographically relevant quantum computer exists. The danger is not only future. Adversaries can record encrypted traffic today and decrypt it later, a tactic known as harvest-now-decrypt-later. In August 2024 the U.S. National Institute of Standards and Technology published its first post-quantum standards: FIPS 203 (ML-KEM, derived from CRYSTALS-Kyber), FIPS 204 (ML-DSA, from CRYSTALS-Dilithium), and FIPS 205 (SLH-DSA, from SPHINCS+). This paper presents a practical migration framework for enterprises. It reviews the quantum threat and Mosca's inequality for timing the transition, summarizes the new standards with their key and signature sizes, and proposes a five-phase roadmap built on crypto-agility: discovery and inventory, risk prioritization, agility engineering, hybrid deployment, and validation. Performance trade-offs are analyzed using documented parameter sizes and illustrative TLS handshake figures. ML-KEM-768 carries a 1,184-byte public key against 64 bytes for an elliptic-curve key, while SPHINCS+ signatures can exceed 17 kilobytes. The work does not report a real deployment. It consolidates published parameters and field guidance into an actionable plan, and it highlights open challenges in certificate sizing, hardware support, and long-lived embedded systems.
Large-scale quantum computers threaten the public-key cryptography that protects enterprise data, communications, and digital identity. Shor's algorithm solves integer factorization and discrete logarithms in polynomial time, which would break RSA, Diffie-Hellman, and elliptic-curve schemes once a cryptographically relevant quantum computer exists. The danger is not only future. Adversaries can record encrypted traffic today and decrypt it later, a tactic known as harvest-now-decrypt-later. In August 2024 the U.S. National Institute of Standards and Technology published its first post-quantum standards: FIPS 203 (ML-KEM, derived from CRYSTALS-Kyber), FIPS 204 (ML-DSA, from CRYSTALS-Dilithium), and FIPS 205 (SLH-DSA, from SPHINCS+). This paper presents a practical migration framework for enterprises. It reviews the quantum threat and Mosca's inequality for timing the transition, summarizes the new standards with their key and signature sizes, and proposes a five-phase roadmap built on crypto-agility: discovery and inventory, risk prioritization, agility engineering, hybrid deployment, and validation. Performance trade-offs are analyzed using documented parameter sizes and illustrative TLS handshake figures. ML-KEM-768 carries a 1,184-byte public key against 64 bytes for an elliptic-curve key, while SPHINCS+ signatures can exceed 17 kilobytes. The work does not report a real deployment. It consolidates published parameters and field guidance into an actionable plan, and it highlights open challenges in certificate sizing, hardware support, and long-lived embedded systems.