Ephemeral coin tracing (ECT) is introduced, a primitive whose tracing capacity is bounded by construction, both in the number of simultaneously traced users and in the number of hops each trace survives.
Abstract
Privacy-preserving payment systems are well understood, yet their adoption in regulated settings, such as central bank digital currencies (CBDCs), institutional stablecoins, and other compliant payment infrastructures, has been limited by concerns over their potential misuse for illicit activities. Regulators counter financial crime with a toolbox of complementary measures to identify, trace, and stop criminal actors. Tracing is one key tool: acting on outside evidence that a user is implicated in a crime such as money laundering, law enforcement follows the suspect's funds through the ledger to uncover laundering routes and accomplices. The tracing schemes proposed in the literature, however, grant authorities unbounded capabilities: once initiated, tracing propagates through the transaction graph or persists across all future transactions of a user, and may eventually deanonymize the entire ledger. Only the goodwill of the authority, or the honesty of a committee, keeps surveillance targeted and temporary. We introduce ephemeral coin tracing (ECT), a primitive whose tracing capacity is bounded by construction, both in the number of simultaneously traced users and in the number of hops each trace survives. The authority issues tracing tags that degrade at each hop; after a protocol-defined number of hops, a tag collapses into a value indistinguishable from that of an untagged coin. Within a tracing period the bound is absolute: no authority, however motivated, can follow a tag past its budget. We formalize ECT, define its security and privacy guarantees, and give two constructions, one over exponential ElGamal and one over Damg{\aa}rd--Jurik encryption.
This paper presents a reference architecture and core protocol rules for digital-value-exchange systems that preserve meaningful user privacy while enabling strong auditability, and concludes that the proposed model can successfully interface with existing payment systems, making it possible to integrate non-custodial, compliance-verified transactions with legacy financial infrastructure.
Santiago De Simone, Geoffrey Goodell, G. Samakovitis· 0 citations
A layered system model and an analysis pipeline that uses prior history as the temporal baseline, applies cumulative pruning and cross-proof propagation to each proof's Commitment Set, and recursively traces the survivors through historical hidden-state transitions to derive the final transaction-level Anonymity Set Size is proposed.
Hanze Guo, Stefanos Chaliasos, Yebo Feng et al.· 0 citations
In the digital era, personal data privacy protection has become a key element of sustainable development. However, most existing literature examines technical, legal, and behavioural aspects in isolation, overlooking the nonlinear propagation mechanisms across different levels. This study integrates a literature review and expert interviews to comprehensively survey existing works and identifies thirteen determinants involving data subjects, data collectors, and regulatory agencies. Building on this foundation, we innovatively integrate a three-stage hybrid methodology—DEMATEL-ISM-MICMAC—to systematically map causal dependencies, hierarchical structures, and attribute robustness among factors. The results reveal that the completeness of legal frameworks and enforcement intensity function as core drivers, whereas trust constitutes a highly dependent yet fragile node. Critical transmission paths encompass the longest chain of “institution–enforcement–cognition–trust” and the shortest chain of “legal provisions→processing transparency”. On this basis, we propose a five-dimensional policy package that (i) reinforces regulatory drivers, (ii) institutionalises trust-repair mechanisms, (iii) leverages trauma-induced learning effects, (iv) optimises transmission pathways, and (v) implements full-cycle collaborative governance, thereby offering a systemic intervention framework to resolve the dilemma of fragmented governance.
Ting Zhang, Zhong-Xian Duan· Humanities and Social Scienc...· 0 citations
Anonymity and accountability are essential properties for our everyday activity on the Internet. However, they appear contradictory, and their reconciliation remains far from reality. Existing approaches fall short in this regard, as they either rely on an on-path trustee, per-packet authorization, per-packet public-key cryptography, or per-session intervention by a central authority. We propose Lacan, a protocol that reconciles anonymity and accountability within a realistic design. In Lacan, a sender enjoys anonymity provided by on-path relays, as long as she complies with a contract established with the receiver. Upon a contract violation, the verifier, an off-path trustee on behalf of the receiver, links the malicious message to the sender's identity indirectly via the packet, path, and session, thereby reducing public-key operations from per-packet to per-session. This linkage remains robust even against malicious relays and receivers, grounded in our novel chain of successor proofs for accountable path reconstruction, together with traceable signatures, path validation, and key-committing encryption. We analyze the anonymity and accountability, implement the protocol, and evaluate the performance.
Naoya Takada, Yutaro Yoshinaka, Kentaro Kita et al.· 0 citations
The challenge for the law shifts from detecting and remedying algorithmic discrimination to governing agent-mediated anonymity as civil rights infrastructure: ensuring access to privacy-preserving agents, regulating abuse without forced identification, and deciding whether retailers may refuse to deal with agents at all.
Anirban Mukherjee, H. Chang· arXiv.org· 0 citations
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