Blockchain Coin Mixing Privacy Protection Mechanism Based On Node Selection

Blockchain,as a decentralized,tamper resistant,traceable,and trusted distributed database,has been widely applied in fields such as finance,public services,and information security.However,due to the traceability,verifiability and other characteristics of blockchain,which are based on the public disclosure of all transaction data on the chain,users face a serious risk of personal privacy leakage.In recent years,with the deepening attention of researchers to privacy issues in blockchain systems,blockchain privacy protection technologies have emerged continuously.Nowadays,representative decentralized coin mixing mechanisms have solved the problems of previous coin mixing mechanisms being unable to resist denial of service attacks,but there are still some shortcomings.1)Introducing third-party nodes for shuffling,the mechanism’s operation is not fully centralized,reducing security;2)Low efficiency,requiring multiple layers of encryption and decryption for each node,resulting in high time complexity;3)Nodes bear different workloads and lack incentive mechanisms.In response to the shortcomings of the existing decentralized coin mixing mechanism,this article proposes two blockchain coin mixing privacy protection schemes based on node selection.The main contents are as follows:1)A coin mixing mechanism based on random node selection was proposed.This scheme eliminates third-party nodes and the shuffling process is completely operated by the coin mixing nodes.All the coin mixing nodes generate a managed address jointly controlled by the nodes,send the amount that needs to be coin mixing to the managed address,and then randomly select multiple shuffling nodes to encrypt their coin mixing transaction output addresses layer by layer with the public key of the shuffling node,and hand them over to the shuffling node for layer by layer decryption and shuffling.After the last shuffling node obtains a complete list of plaintext addresses,Broadcast the address list to ordinary coin mixing nodes for verification,and generate a common final substitution to obtain the final output address list,completing the coin mixing transaction.This mechanism achieves complete decentralization,solves the problem of asset theft in third-party nodes,and reduces the time required for encryption,decryption,and verification processes.Security analysis and experimental analysis indicate that this mechanism enhances security,avoids asset theft issues,and reduces the time cost of the coin mixing mechanism.2)A coin mixing mechanism based on reputation node selection was proposed.This scheme is improved on the basis of the first scheme,taking into account the occurrence of malicious nodes among coin mixing participants.A reputation based incentive mechanism is added,and shuffling nodes that bear more workload will receive more reputation value rewards.When the coin mixing fails,the violating operator will deduct reputation points.Nodes with higher reputation values will have higher priority in the node selection stage.By incentivizing participants through reputation values,reducing the risk of wrongdoing,and improving the stability and security of the coin mixing mechanism.And by selecting different nodes to transmit messages,the time consumption of message transmission is dispersed and efficiency is improved.Security analysis shows that this scheme effectively reduces the impact of malicious nodes on the coin mixing mechanism and improves the stability of the coin mixing mechanism.Meanwhile,experiments have shown that this scheme disperses time consumption through parallel operations and improves the operational efficiency of the coin mixing mechanism.