Study Finds Widespread Cross-Chain Cryptographic Key Reuse Threatening User Privacy

Global: Study Finds Widespread Cross-Chain Cryptographic Key Reuse Threatening User Privacy

A new arXiv preprint reports that cryptographic keys are being repeatedly used across multiple cryptocurrency networks, a practice that can erode both privacy and security for users. The analysis covers six major blockchains—Bitcoin, Ethereum, Litecoin, Dogecoin, Zcash and Tron—and quantifies the extent of cross-chain key reuse.

Background on Address Reuse

Reusing cryptocurrency addresses within a single network has long been recognized as a privacy risk because it links multiple transactions to the same public identifier. Prior research has largely focused on direct address matching or simple format conversions, leaving the broader phenomenon of cross-chain reuse insufficiently explored.

Methodological Shift to Public Keys

The authors of the paper shift the investigative focus from addresses to the underlying public keys, which are common to both UTXO‑based and account‑based systems. By extracting and comparing public keys, the study is able to identify reuse even when the resulting address formats appear incompatible, such as those generated by Bitcoin and Ethereum.

Extent of Reuse Across Networks

Empirical results indicate that key reuse is both extensive and active across the examined blockchains. The paper provides quantitative metrics that demonstrate a non‑trivial proportion of transactions are linked to the same public key on multiple platforms, confirming that cross-chain reuse is a recurring phenomenon.

Implications for Privacy and Security

Because a single public key can be associated with activity on several networks, adversaries capable of linking that key can construct a more comprehensive profile of a user’s financial behavior. This aggregation undermines the pseudonymity that many blockchain users rely on and may expose them to targeted attacks or regulatory scrutiny.

Novel Clustering Techniques

To overcome the limitations of heuristic‑based approaches, the researchers introduce clustering methods that directly associate entities through shared secret keys. These techniques do not depend on address pattern analysis, thereby reducing false positives and providing a more reliable mapping of cross‑chain activity.

Significance and Future Directions

The study claims to be the first to systematically expose and quantify cross‑chain key reuse between UTXO and account‑based cryptocurrencies. The authors suggest that their findings could inform the development of best‑practice guidelines for wallet implementations and encourage further academic investigation into mitigation strategies.

This report is based on information from arXiv, licensed under Academic Preprint / Open Access. Based on the abstract of the research paper. Full text available via ArXiv.