Abstract: Blockchain is a distributed ledger technology with the characteristics of decentralization,non-tampering,and data disclosure.However,data disclosure has led to the security risk of privacy leakage in the blockchain.The introduction of the mixing center as an intermediary cuts off the connection between the transferor and the receiver,and achieves the purpose of protecting the privacy of both parties to the transaction,but it still has some security loopholes,such as the mixing center can still grasp this association,the mixing center may forge the transfer,and the transferor may deny the transaction.Therefore,a quorum-blind signature based on arbitration authentication mixing technology is proposed,which uses ring-blind signatures to solve the problem of association between the mixing center,and uses arbitration authentication to solve the problem of the mixing center and user violations.Compared with the traditional coin mixing scheme,it has incomparable advantages,which can well solve the problems existing in the traditional coin mixing scheme,and has the characteristics of anonymity,non-repudiation,non-forgery,anti-Dos,etc.,which improves the traditional coin mixing service and can further protect user privacy.The response time of this scheme is positively correlated with the number of users and the number of mixing centers.Compared to the Mixcoin and Blindcoin schemes,the response time is slightly longer,but shorter than that of Coinjoin and Coinshuffle schemes.Additionally,compared to other schemes,this scheme can effectively prevent deception by users and mixing centers,better protecting transaction privacy.

Key words: Blockchain, Privacy breaches, Coin mixing center, Ring-blind signatures, Anonymity