Coin Mixing Protocols: A Structured Evaluation and Review of Detection Methods

ABSTRACT Cryptocurrencies, beginning with Bitcoin, have been widely adopted as they enable transactions while preserving user privacy. However, prior studies have revealed that the anonymity provided by cryptocurrencies is incomplete, with Bitcoin in particular relying on pseudonymity rather than true anonymity. To address this limitation, a variety of coin mixing protocols have been proposed to enhance anonymity. Yet, enhanced anonymity also carries the risk of misuse by malicious actors, and coin mixing protocols are no exception. Several mixing services built on these protocols have been employed in laundering illicit funds from major hacks, drawing the attention of regulators. This paper analyzes the strengths and limitations of existing coin mixing protocols and evaluates them from the perspectives of privacy, security, efficiency, and practicality. Furthermore, it reviews research on the detection of mixing protocols and discusses future directions for advancing this line of work.