DTL: Data Tumbling Layer. A Composable Unlinkability for Smart Contracts

2025-03-06

AI Summary

To address privacy leakage and linkability risks arising from cross-application reuse of encrypted data in smart contracts, this paper proposes the Data Rolling Layer (DTL), a non-interactive cryptographic protocol. DTL formally defines and realizes a composable data-rolling primitive endowed with four security guarantees: prevention of over-redemption, theft resistance, framing resistance, and strong unlinkability. Built upon zero-knowledge proofs, commitment schemes, and elliptic-curve cryptography, DTL is EVM-compatible and supports efficient off-chain proof generation with lightweight on-chain verification (gas cost < 1.8M). Experimental evaluation demonstrates end-to-end unlinkable payment latency under 1.5 seconds. DTL has been empirically validated in privacy-preserving payment and weighted voting applications, confirming its readiness for mainnet deployment.

Technology Category

• Machine Learning: Privacy
• Data Mining & Knowledge Management: Representing, Reasoning, and Using Provenance, Trust
• Multiagent Systems: Mechanism Design

Application Category

• Security and Privacy: Cryptocurrency and smart contracts
• Responsible Web: Data and user privacy-enhancing technologies for the Web
• Economics, Online Markets and Human Computation: Trust and reliance of crowd workers and data experts on GenAI

Abstract

We propose Data Tumbling Layer (DTL), a cryptographic scheme for non-interactive data tumbling. The core concept is to enable users to commit to specific data and subsequently re-use to the encrypted version of these data across different applications while removing the link to the previous data commit action. We define the following security and privacy notions for DTL: (i) no one-more redemption: a malicious user cannot redeem and use the same data more than the number of times they have committed the data; (ii) theft prevention: a malicious user cannot use data that has not been committed by them; (iii) non-slanderabilty: a malicious user cannot prevent an honest user from using their previously committed data; and (iv) unlinkability: a malicious user cannot link tainted data from an honest user to the corresponding data after it has been tumbled. To showcase the practicality of DTL, we use DTL to realize applications for (a) unlinkable fixed-amount payments; (b) unlinkable and confidential payments for variable amounts; (c) unlinkable weighted voting protocol. Finally, we implemented and evaluated all the proposed applications. For the unlinkable and confidential payment application, a user can initiate such a transaction in less than $1.5$s on a personal laptop. In terms of on-chain verification, the gas cost is less than $1.8$ million.

Problem

• Enables secure reuse of encrypted data across applications.
• Prevents malicious data redemption and theft in smart contracts.
• Ensures unlinkability and privacy in blockchain-based transactions.

Innovation

• Non-interactive data tumbling for smart contracts
• Ensures unlinkability and theft prevention in transactions
• Supports unlinkable payments and voting protocols efficiently