Abstract

The Privacy–Security Dilemma of Digital Money: Relay Attacks, Offline Double Spending, Financial Integrity and the Race Toward Hardware-Enforced Payment Finality

Technical Subtitle: A Hardware-Rooted, Privacy-Preserving CBDC and Digital Payment Architecture Addressing Offline Transaction Security, Cryptographic Authorization, Cross-Border Settlement, and Technical Alignment with IMF CBDC Research and FATF Financial-Integrity Objectives

Industry and Infrastructure Relevance: European Central Bank (ECB); Digital Euro; People's Bank of China (PBOC); e-CNY; Reserve Bank of India (RBI); Digital Rupee; U.S. Dollar-Backed Stablecoins; Visa; Mastercard; Swift; Bitcoin; Tokenized Deposits; International Monetary Fund (IMF); Financial Action Task Force (FATF); and Global Digital Payment Infrastructure.

Foundational International Patent Application: PCT/IB2026/055615 — THE DAS PROTOCOLS

International Publication: WO 2026/150382 A2

Filed: 4 June 2026

Published: 16 July 2026

ABSTRACT

The digital euro is moving toward a real-world pilot. Dollar-backed stablecoins are entering a new regulatory and commercial phase. China's e-CNY continues to evolve. But a fundamental question remains for the future of digital money: Can a payment be private, compliant, usable offline, and resistant to unauthorized financial execution at the same time?

The next generation of monetary infrastructure is being designed around competing requirements that are difficult to satisfy simultaneously.

Consumers expect digital cash to protect their privacy. Regulators require effective financial-integrity safeguards. Payment operators require fraud resistance, reliability and recoverability. Central banks require monetary integrity and clearly defined settlement authority. Meanwhile, offline digital currency must support transactions without continuous connectivity, when conventional real-time verification may be unavailable.

A cryptographically valid payment message does not necessarily prove that the intended transaction was authorized, that the devices were genuinely nearby, that the underlying spending state remains valid, or that the payment is permitted to become financially effective.

This creates a technically important distinction between payment authentication and payment finality.

An attacker may attempt to relay an otherwise valid proximity-payment exchange, replay captured transaction material, exploit stale authorization, manipulate wallet state, abuse a compromised device, or redirect payment execution across an unintended recipient, merchant, jurisdiction or settlement interface.

Although cryptographic protocols, secure elements, transaction monitoring, hardware attestation and anti-fraud controls already address significant parts of these threats, their combined effectiveness depends on implementation details, trusted hardware assumptions, recovery mechanisms and the exact boundary at which monetary value becomes transferable or final.

The challenge becomes particularly demanding for offline central bank digital currencies (CBDCs). A device may have to validate and transfer locally stored value without contacting a central ledger at the moment of payment, while still limiting double spending, cloning, rollback, replay, unauthorized disclosure and subsequent reconciliation conflicts.

At the same time, privacy creates an additional architectural requirement. Preventing financial misuse should not automatically require every merchant, intermediary, network observer or central settlement operator to receive a persistent identifier and a complete record of a person's transaction behavior.

The European Central Bank's proposed digital euro illustrates the importance of this distinction through its separate online and offline payment models and its emphasis on cash-like privacy for offline transactions.

China's e-CNY, India's digital rupee, regulated dollar-backed stablecoins and Bitcoin present additional but materially different models of monetary issuance, wallet control, participant identification, transfer authorization and settlement.

The global challenge is therefore not confined to one currency or ledger.

It is the absence of a universally applicable way to establish, with independently verifiable evidence, that the particular payment becoming effective is the payment actually authorized under the applicable technical and legal conditions.

This article examines a proposed hardware-rooted execution-finality architecture disclosed in international patent application PCT/IB2026/055615 (WO 2026/150382 A2), filed on 4 June 2026 and published on 16 July 2026.

The disclosed architecture introduces a separation between the creation of a payment instruction and the authorization of its actual financial consequence.

A proposed operation is represented as a Candidate Payment Act or Candidate Settlement Act and remains in a Non-Effective State until the required protected validation conditions are satisfied.

A Protected Enforcement Domain (PED) evaluates machine-verifiable predicates relating, where applicable, to transaction authority, amount, currency, intended recipient, merchant, wallet state, spending limits, nonce freshness, revocation, jurisdiction, financial-integrity requirements and the designated payment-effectuation interface.

The architecture further describes Ledger-Anchored Validation Receipts (LAVRs), including dual-receipt arrangements that distinguish privacy-preserving transaction evidence from more sensitive protected information needed for authorized reconciliation, investigation or dispute resolution.

In offline embodiments, locally generated evidence can be reconciled or anchored when connectivity becomes available.

Following the required protected validation and state commitments, the architecture may release a scoped, non-bearer financial capability bound to the particular transaction and intended Financial Finality Sink.

The controlled wallet, payment interface or settlement component verifies that capability before allowing the governed financial operation to become effective.

Five technical challenges addressed by the proposed architecture

1. Relay attacks and payment-context substitution

A valid credential or proximity-payment message may be relayed or presented outside its intended transaction context.

The proposed embodiments bind payment authority to specified transaction details, protected state and a designated effectuation boundary, with optional proximity and anti-relay evidence.

This may provide additional protection against certain transaction-substitution or relay scenarios. It does not, by itself, establish physical proximity or eliminate all relay attacks; that requires appropriate protocols, device capabilities and independent security testing.

2. Offline double spending, replay and wallet rollback

Offline digital cash requires locally enforceable controls because central verification may be unavailable.

The disclosed embodiments combine sealed spending-state advancement, monotonic counters or equivalent protected state, transaction freshness, offline spending limits, dual-device receipts and subsequent reconciliation.

The objective is to reduce the ability of copied messages, stale wallet snapshots, repeated payment artifacts or interrupted transactions to create unauthorized value transfers.

3. Privacy-preserving financial-integrity enforcement

The disclosure proposes separating persistent identity, transaction authorization, spending capabilities and ordinary validation evidence through mechanisms including Session-Scoped Virtual Identities (VIs), Compliance Jurisdiction Tokens (CJTs) and Dual-LAVR structures.

This allows investigation of designs in which a payment's eligibility may be verified without routinely exposing all underlying personal identifiers to every participant.

Where legally required, more sensitive information may remain accessible through separately governed resolution procedures.

These designs require formal analysis of transaction unlinkability, metadata leakage, lawful access and compliance effectiveness.

4. FATF-related compliance and IMF CBDC design objectives

FATF Recommendations establish international standards concerning risk-based anti-money-laundering and counter-terrorist-financing measures, targeted financial sanctions and relevant payment-transparency requirements.

The IMF's CBDC Virtual Handbook examines challenges relating to privacy, financial integrity, resilience, offline payments, cross-border interoperability and settlement design.

The proposed architecture investigates whether applicable authorization and financial-integrity conditions can be verified at protected payment-effectuation boundaries rather than relying exclusively on earlier checks or later monitoring.

However, the IMF does not certify the architecture, and FATF standards must be implemented through applicable national legal and regulatory arrangements. Technical validation does not eliminate institutions' monitoring, reporting or supervisory responsibilities.

5. Cross-border CBDC and multi-rail settlement authority

As central-bank digital money, tokenized deposits, stablecoins and automated payment systems evolve, a single instruction may cross multiple institutions and settlement infrastructures.

The disclosed architecture proposes binding authorization to the particular financial operation, currency or asset, participating authority, jurisdictional scope and designated settlement interface.

Relevant embodiments explore multiple independently governed CBDC systems and protected validation before specified debit, credit, release, redemption or other settlement operations.

The proposed controls must coexist with the authoritative settlement rules of the participating monetary systems.

WHY THIS MATTERS NOW

Digital-money deployment is advancing faster than any universal agreement on how privacy, offline security and cross-infrastructure financial authority should be implemented together.

The ECB is preparing a digital euro pilot for the second half of 2027 and is pursuing secure-hardware solutions for offline payments.

The United States has enacted the GENIUS Act framework for payment stablecoins, while its current federal policy does not support establishing a U.S. retail central bank digital currency. Consequently, dollar-backed private stablecoins must not be confused with a Federal Reserve-issued digital dollar.

FATF's March 2026 report on stablecoins and unhosted wallets identifies continuing risks involving peer-to-peer transfers and illicit financial activity.

IMF research separately identifies offline CBDC threats that include transaction replay, cloning, man-in-the-middle attacks and device tampering.

These developments create a timely engineering question for central banks, payment networks, secure-element manufacturers, wallet providers, stablecoin issuers and financial infrastructure operators:

Will future payment systems merely verify that a transaction message is authentic—or will they also verify that the exact financial effect is authorized at the boundary where value can actually move?

The DAS Protocols disclosure positions protected execution finality as a candidate additional security architecture for this question.

Its proposed mechanisms are relevant to privacy-preserving CBDCs, offline digital cash, agent-initiated payments, regulated stablecoin transfers and sovereign cross-border settlement.

For Bitcoin and other permissionless cryptocurrencies, the potential integration is limited to controlled components such as wallets, custody systems, signing services and regulated bridges. It does not replace decentralized consensus or govern transactions executed independently of those components.

The central research proposition is that privacy and accountability should be designed together, while payment authorization must remain distinguishable from payment execution.

Whether the disclosed architecture achieves measurable improvements in relay resistance, double-spend protection, privacy, compliance or settlement integrity must be established through independent prototypes, comparison against existing secure-payment designs and adversarial testing.

The stakes are significant: as digital currencies become more widely used and payment decisions increasingly involve autonomous software, a failure at the boundary between authorization and effectuation can become an actual financial consequence rather than merely an incorrect software decision.

HIGH-DISCOVERABILITY INDUSTRY KEYWORDS

Digital Euro; ECB Digital Euro; e-CNY; Digital Yuan; RBI Digital Rupee; U.S. Dollar Stablecoins; GENIUS Act; Central Bank Digital Currency (CBDC); Privacy-Preserving CBDC; Offline Digital Cash; Offline Payment Security; Digital Currency Relay Attacks; NFC Relay Attack Prevention; Offline Double-Spend Prevention; CBDC Wallet Security; Cryptographic Payment Authorization; Hardware-Rooted Payment Finality; Protected Enforcement Domain; Financial Finality Sink; Ledger-Anchored Validation Receipt; Dual-LAVR; Compliance Jurisdiction Token; Zero-Knowledge Compliance; Privacy-Enhancing Technologies; FATF AML/CFT; IMF CBDC Virtual Handbook; Cross-Border CBDC Settlement; Tokenized Deposits; Stablecoin Settlement; Agentic Payments.

INDUSTRY ALIGNMENT, NON-ENDORSEMENT AND TECHNICAL VALIDATION DISCLAIMER

This article presents an AI-assisted technical interpretation of the DAS Protocols foundational disclosure and a comparative assessment of publicly available digital-currency research, institutional roadmaps and payment-security requirements.

References to the ECB, PBOC, RBI, IMF, FATF, BIS, Visa, Mastercard, Swift, Bitcoin, dollar-backed stablecoins and other institutions or monetary systems indicate research relevance and possible technical integration environments only.

No endorsement, adoption, certification, collaboration, licensing, copying, infringement, regulatory approval or standards incorporation is asserted.

The article does not claim that every currently deployed digital currency is vulnerable to a successful relay attack, that all financial-integrity controls are ineffective, or that privacy-preserving CBDC systems have achieved no practical security solutions.

The proposed architecture is not established to provide absolute anonymity, guaranteed relay-attack prevention, immunity to double spending, universal financial-crime prevention or unconditionally non-bypassable settlement enforcement.

The IMF CBDC Virtual Handbook is a policy and research resource, not a binding technical certification programme. FATF Recommendations establish international standards implemented through jurisdiction-specific laws and regulatory arrangements.

The digital euro, e-CNY, digital rupee, privately issued dollar-backed stablecoins and Bitcoin have different issuance models, legal characteristics and settlement mechanisms. Potential implementations must be evaluated separately.

All embodiment descriptions, patent-claim interpretations and AI-generated industry comparisons should be independently cross-checked against the original published patent specification, current institutional documentation, applicable legal instruments and validated security research.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

Download

Share

COinS