Design And Implementation Of Blockchain Based Privacy-Preserving Transaction System For V2G

V2G（Vehicle-to-Grid）is an important part of smart grid in the future,and plays an important role in maintaining the stability of power grid.However,with the popularity of V2G,there is a problem of user privacy security.The traditional centralized trading platform is difficult to protect user privacy.The user’s identity,location,transaction amount and deeper privacy information will be threatened.Blockchain is a distributed and decentralized system,which has the characteristics of security and tamper proof.It is widely used in the field of digital currency transaction.Through the application of cryptography technology such as zero knowledge proof,blockchain can well hide the user’s transaction records and identity information,so as to protect the user’s privacy.In addition,as an underlying technology,blockchain can also support smart contract.Smart contract is a safe,reliable and automatic program,which can provide any computing service for users in theory.In the scenario described by V2G,when electric vehicles trade with power grid system or other electric vehicles,considering the mutual trust between the two parties,a trusted third party is needed as a guarantee to prevent any party from cheating,and blockchain can be well qualified for this role.This paper mainly introduces the design and implementation of privacy-preserving transaction system for V2G based on blockchain.The system can realize the power transaction of both users under the condition of protecting users’ privacy.In the process of the system,both parties negotiate in the blockchain,the payer pays a certain amount of money in advance,and exchanges power through the transaction voucher off the chain,and finally settles in the blockchain system.In this system,we use zero knowledge proof technology to hide the information of transaction participants and transaction amount,so as to protect the user’s privacy in the process of transaction.At the same time,we also use the micropayment technology based on hashchain to complete the connection between the off-chain and on-chain part,which not only gives full play to the role of smart contract,but also reduces the transaction cost and improves the work efficiency of the blockchain,which makes it possible to process large-scale transactions under the system.