This paper explores the transition from theoretical quantum-risk planning to the practical implementation of post-quantum cryptography in the homeland security sector. It focuses on space infrastructure, critical infrastructure protection, and national resilience, assessing threats posed by the "harvest now, decrypt later" approach, post-quantum cryptographic standards, and vulnerabilities in positioning, navigation, and timing systems. The analysis also addresses governance challenges, procurement requirements, and satellite security, proposing resilience-oriented strategies for the protection of national infrastructure. Key recommendations include adopting hybrid cryptographic solutions, automating the detection of vulnerable systems, continuous attestation, cryptographic agility in orbit, and establishing a Space-Quantum Reserve to bolster long-term resilience against quantum threats.
Quantum computing threatens the classical cryptographic systems underpinning financial infrastructure, exposing payment platforms, interbank networks, and digital services to Harvest-Now-Decrypt-Later (HNDL) risks. This study systematically reviews quantum threats and post-quantum cryptographic readiness in the financial sector to assess preparedness, identify implementation challenges, and synthesize migration pathways aligned with emerging standards. A PRISMA-guided review of 17 peer-reviewed studies published between 2020 and 2025 was conducted, examining quantum threat models, post-quantum cryptographic schemes, quantum key distribution architectures, and sector-specific deployment barriers. The review finds that lattice-based schemes, especially CRYSTALS-Kyber and CRYSTALS-Dilithium, are the leading candidates for financial adoption, while hybrid cryptographic approaches offer the most feasible transition strategy. However, the current evidence base is predominantly simulation-driven, with limited real-world deployment and validation. The study provides a sector-specific synthesis of quantum threats, post-quantum readiness, and migration pathways in financial systems, and advances an integrated readiness and migration framework based on cross-study thematic analysis.
Abstract Classical computing architectures cannot reasonably solve computationally challenging problems, such as those of RSA public-key encryption, Diffie-Hellman key exchange, and elliptic curve cryptography, which form the cryptographic foundations of modern enterprise information security. Superposition and entanglement phenomena can be used to make quantum computers efficient in solving these problems, which are efficiently solved by Shor's algorithm and Grover's algorithm, and make existing cryptographic infrastructure entirely insecure. While quantum computing is fault-tolerant and still under development, the 'harvest now, decrypt later' threat model by which adversaries can harvest encrypted data now to be decrypted later when they can operate quantum systems signals that the cryptographic threat is present, not future. The objective of this study is to examine the current state of enterprise cryptographic readiness against threats in the quantum era and to create a model for organizational transition to the new cryptographic standards in the quantum era, which is called the Quantum-Resilient Security Architecture (QRSA) Framework. It uses a mixed-methods research methodology, consisting of a systematic literature review, an expert Delphi survey of 38 cybersecurity practitioners from 16 countries, and a qualitative analysis of five enterprise organizations, to examine the state of quantum-capable cryptographic protocols, the readiness of organizations in the technical, governance and capability aspects, and the most important enablers and blockers for the post-quantum migration. The key findings include that: 94 percent of enterprise systems assessed are today still using quantum-vulnerable cryptographic primitives; less than 12 percent of organizations surveyed have started formal planning efforts for quantum migration; and, in most of the cases analyzed, the National Institute of Standards and Technology (NIST) post-quantum cryptography standardization process has not made significant impacts on enterprise security roadmaps. The QRSA Framework offers a staged migration architecture based on the NIST standardized algorithms such as CRYSTALS-Kyber, CRYSTALS-Dilithium and SPHINCS+ that integrates with the enterprise security infrastructure. Contributions include cybersecurity governance scholarship, enterprise risk management theory, and information security policy.