Traceable Mixing Scheme for Bitcoin

Abstract

Mixing is an important way for privacy protection among digital currency such as Bitcoin.However,on the one hand,Bitcoin mixing protects user privacy,on the other hand,it facilitates the transfer of assets for illegal activities such as ransomware and Bitcoin theft.In this paper,we propose a traceable scheme for Bitcoin mixing.The scheme aims to protect the privacy of legi-timate users and can trace the illegal assets.The system is regulated by trusted third party,user anonymity and traceability based on the group signature which is constructed by bilinear groups and strong Diffie-Hellman assumption.When there is a need for tracing,the regulator can determine the signed user through the system private key,so as to determine the illegal asset transfer path.Security analysis shows that the scheme can trace the illegal asset transfer without modifying the current Bitcoin system,meanwhile,the solution provide privacy protection and asset safety for legitimate users.Furthermore,the scheme provides a refe-rence direction for the research on digital currency privacy protection.