Research On Identity Privacy Protection Technology Of Transaction In Consortium Blockchain

Blockchain technology plays an important role in many fields such as finance,supply chain management and medical treatment due to its decentralization,traceability,non-tampering and other features.However,the openness and transparency of blockchain transaction records also pose a threat to users' transaction privacy.Although some blockchain applications provide protection for users' transaction privacy by means of cryptography technology,excessive protection of users' privacy makes it difficult to supervise users' identities.Therefore,while protecting the privacy of users' transactions,it is also important to be able to supervise transactions.At present,some public blockchain applications adopt a strong privacy protection mechanism,but due to the characteristic of free access in public blockchain,it is difficult to trace the real identities of users.The authorized access and exit mechanism in consortium blockchain is suitable for the application scenario of supervising users' identities,but the existing identity privacy protection schemes in consortium blockchain still have the disadvantage that transactions may be linked.Therefore,it's of great significance to research how to provide strong privacy protection for users and supervise the identities of transaction participants at the same time.Focusing on the privacy protection and supervision of transaction in blockchain,this paper designed a supervised anonymous transaction protocol for consortium blockchain from two aspects: transaction recipient and transaction sender.The main work of this paper is as follows:(1)In order to protect and supervise the identity privacy of the transaction recipient,the one-time address scheme in Crypto Note was improved,and an improved one-time address scheme based on DLIN encryption was proposed.In the improved scheme,the number of elements of users' keys was reduced,and the storage space of users' keys was saved.The role of regulator was added,and DLIN encryption was adopted,so that the regulator could obtain the blockchain address of the recipient while the identity privacy of the recipient was protected.Based on zero-knowledge proof technology,the reliability of the encrypted data was ensured and the privacy of recipient was not disclosed.Security analysis showed that the scheme could satisfy anonymity,supervisability,reliability and the security of one-time private key of the transaction recipient;(2)In order to protect and supervise the identity privacy of the transaction sender,the linkable ring signature in Crypto Note was improved,and a linkable revocable ring signature scheme called LRRS was proposed.The scheme satisfied anonymity,unforgeability,non-defamation,linkability and anonymity revocability.Anonymity protected the identity privacy of the transaction sender,linkability was used to detect the double spending behavior of the transaction sender,and anonymity revocability enabled the regulator to supervise the identity of the transaction sender;(3)The MLSAG scheme in Ring CT was improved.Based on LRRS,a revocable MLSAG scheme named RMLSAG was proposed.The scheme also satisfied anonymity,unforgeability,non-defamation,linkability and anonymity revocability.Compared with LRRS,RMLSAG allowed the sender of transaction to use multiple keys to generate ring signature,which improved the efficiency of multi-input transactions.When the number of signature keys was same,RMLSAG ring signature's length was shorter;(4)Combined with the existing data privacy protection mechanism and the access mechanism of consortium blockchain,a supervised anonymous transaction protocol for consortium blockchain was proposed.The identity privacy protection scheme that can be regulated in the protocol was implemented by using Go language.The experiments further verified the correctness and feasibility of the schemes.The experimental results showed that the efficiency of RMLSAG was significantly improved compared with LRRS.