Fail-Closed Cryptographic Execution Control for Digital Currencies Offline Payments with Cash Like Privacy

Abstract Offline payment systems must balance fraud resistance, privacy, and operation without continuous connectivity. Existing approaches often rely on proximity assumptions, risk limits, identity-linked controls, or post-transaction reconciliation, leaving a continuing challenge for secure disconnected payments. This paper presents a conceptual execution-time authorization model in which an offline transaction is treated as a proposed value transfer that remains subject to a final governance decision before becoming effective. The framework considers whether authorization could depend on bounded identity, jurisdictional and policy conditions, approved execution behavior, and relevant transaction context rather than on proximity or persistent identity alone. At a high level, the model aims to support stronger resistance to relay, replay, unauthorized reuse, and other offline-payment risks while reducing dependence on continuous connectivity and unnecessary identity correlation. The proposal is intentionally implementation-neutral. It does not prescribe a particular cryptographic predicate, identity mechanism, token structure, trusted hardware design, behavioral fingerprinting method, validator architecture, or CBDC protocol. It is presented as a research model for exploring privacy-preserving, fail-closed authorization at the point where an offline payment becomes final. The broader principle is simple: offline payment security should depend on valid authority at transaction finality, not merely on proximity or possession.