Quantum-Safe Accounting and Finance: Threats, Standards, and Secure System Design for the Post-Quantum Era

Abstract: This study develops a unified approach to quantum-safe security in accounting and finance by linking concept analysis, a design framework, and implementation guidance to measurable risk reduction. Concept analysis distinguishes confidentiality lifetimes, “harvest-now-decrypt-later” exposure, and cryptographic dependence across ledgers, payments, reporting pipelines, and audit trails. Building on this, a layered framework is articulated comprising (i) threat taxonomy and impact surfaces for financial workflows; (ii) standards alignment with post-quantum cryptography (PQC) suites and crypto-agility policies; (iii) key- and certificate-lifecycle orchestration using HSM-backed services; and (iv) controls for ledger integrity, non-repudiation, and regulatory evidence. The core problem addressed is the absence of end-to-end, standards-compatible designs that deliver quantum resilience without disrupting performance, interoperability, or compliance. Methodology integrates formal threat modeling, standards mapping, and reference-architecture synthesis with scenario evaluation in representative financial processes (inter-system reconciliation, e-signature workflows, and archival protection). Results show that phased PQC migration with automated key rotation and dual-stack validation reduces exposure windows, preserves auditability, and maintains throughput within target bounds for typical batch and near-real-time workloads. Impact arises from procurement-ready patterns, crypto-agile runbooks, and assurance artifacts that support regulatory review and external audit. The implications include actionable migration roadmaps for institutions, improved durability of financial records against future cryptanalytic advances, and clearer accountability through evidence bundles that connect controls to quantifiable risk reduction. Keywords: quantum-safe cryptography, post-quantum cryptography (PQC), financial systems security, accounting information systems, harvest-now decrypt-later, crypto-agility, key management and HSM, digital signatures and non-repudiation, ledger integrity, regulatory compliance, audit evidence, zero-trust architecture, certificate lifecycle, risk assessment and migration planning