Research On The Application Of Privacy Protection Technology Based On Zero Knowledge Proof In Consortium Blockchain

With the characteristics of decentralization,non-tampering,and high transparency,blockchain technology has important research and application value in many fields such as finance,supply chain management,military,government,and medical care.Although the openness and transparency of the blockchain ledger facilitates the maintenance of the ledger by system nodes,it also brings about problems such as privacy leakage.With the strong privacy protection scheme proposed for blockchain systems,issues such as the inability to regulate transactions come into play.Therefore,the realization of supervision on the basis of privacy protection is the key issue for the practical application of blockchain technology.Strong privacy protection schemes are generally used in public blockchain,but due to the free access to public blockchain systems,it is difficult to supervise user identities;While there is an access mechanism for consortium blockchain system to meet the demand of identity supervision,the existing privacy protection scheme still suffers from the problem that transactions can be linked and identity privacy is compromised.In addition to meeting the privacy protection and supervision requirements for the identities of transaction participants,the privacy protection and auditability of transaction content are equally important.Therefore,this paper focuses on the privacy protection and supervision issues in consortium blockchain,and studies from two aspects of identity privacy and supervision and content privacy and auditability,then designs a supervised anonymous transaction protocol suitable for the consortium blockchain system.The main research of this paper are as follows:(1)In order to protect the identity privacy of users in the consortium blockchain system,the Identity Mixer anonymous credential scheme is improved,and an anonymous credential scheme called IIM based on zero-knowledge proof protocol and short random signature is proposed.Based on the short random signature scheme,the improved scheme solves the limitation of the linear relationship between the size of the certificate signature and the number of attributes in the original scheme;Based on the zero-knowledge proof protocol,the improved scheme can not only realize anonymous identity authentication,but also realize selective disclosure of user attributes during the presentation of anonymous credentials.Security analysis shows that the IIM scheme satisfies zero knowledge,unforgeability,unlinkability and anonymity.(2)In order to realize the identity supervision of transaction participants in the consortium blockchain system,a supervisable anonymous authentication scheme has been improved,and the supervised anonymous credential scheme called ISAA based on the IIM scheme was proposed.The improved scheme is based on the original scheme framework and combines the IIM scheme,short random group signature scheme and zero-knowledge proof protocol,which not only ensures the anonymity and identity supervision of users,but also provides stronger identity privacy than the original scheme,and higher operational efficiency and storage performance.(3)In order to realize the privacy protection and auditability of the transaction content in the consortium blockchain system,a supervised anonymous transaction protocol suitable for the consortium blockchain Hyperledger Fabric system is proposed.The protocol is based on the ISAA scheme,which realizes the privacy protection and supervision of the identities of anonymous transaction participants;At the same time,combined with the integrated signature and encryption scheme and the zero-knowledge proof protocol,it realizes the privacy protection and auditability of anonymous transaction content,and achieves the purpose of providing a solution that balances privacy and supervised auditing for asset transactions in the consortium blockchain.Security analysis shows that supervisory anonymous transaction protocols satisfy transaction confidentiality,authenticity,reliability,anonymity,identity supervisibility,and content auditability.Based on the privacy protection technology of zero-knowledge proof,this paper designs a supervisory anonymous transaction protocol suitable for consortium blochchains.The protocol can realize the privacy protection and supervision of user identities in the system and the privacy protection and auditability of transaction content.It can be widely used in consortium blockchain transaction systems with privacy protection and regulatory requirements.