Practical Considerations for Post-Quantum Cryptographic Migration in Financial Systems

This preprint examines the practical and operational challenges associated with migrating financial systems to post-quantum cryptography (PQC). While recent standardization efforts have finalized quantum-resistant cryptographic primitives, real-world adoption remains constrained by legacy infrastructure, regulatory and compliance requirements, performance trade-offs, and limited cryptographic agility in existing deployments. The paper approaches post-quantum migration as a systems-level problem rather than a purely cryptographic one, analyzing threat models such as “harvest now, decrypt later” and the implications for long-term data confidentiality in regulated financial environments. It evaluates common migration strategies, including hybrid cryptographic schemes and phased deployment, highlighting their operational risks and limitations. Building on these observations, the work proposes an adaptive and self-healing migration framework designed to support incremental adoption of PQC while preserving availability, compliance, and risk tolerance. The framework emphasizes continuous monitoring, policy-driven cryptographic agility, and safe rollback mechanisms. This work is intended to serve as a practical reference for researchers, engineers, and decision-makers planning quantum-safe transitions in high-assurance financial systems.