A blockchain-based coin mixing protocol with certificateless signcryption

Very recently, Bitcoin has been used as a private coin, and some people have applied Bitcoin in their private/confidential financial transactions. In 2012, researchers found that Bitcoin cannot provide complete anonymity, and its users are traceable. In 2013, the feature of user untraceability appeared in the Zerocoin project. The first coin mixing protocol called CoinJoin was launched in the same year. This paper presents a new coin mixing protocol called CLSCmix using a certificateless signcryption (CLSC). The CLSCmix protocol, in addition to providing general features of coin mixing protocols, supports new attractive properties such as a private one-party payment service, and selectable mixing time, and supports several groups of users who want to execute the mixing protocol. The security analysis in the random oracle model (ROM) of the CLSCmix protocol demonstrates that it supports all of the security requirements of mixing protocols. According to the comparison, the CLSCmix offers more security features than existing mixing protocols, and it is more efficient than other compared mixing protocols.