Research On Privacy-preserving Fair Data Trading Scheme Based On Smart Contract

With the advent of the era of big data,the value of data for enterprises and individuals has become more and more important.Te trade of data as a commodity has become the focus of enterprises and individuals.However,there are many diferences between data and traditional commodities,which makes the trade of data cannot simply apply the mode of traditional e-commerce industry.How to safely and fairly trade data commodities has become a concern of both the industry and academia.In the traditional e-commerce feld,there exists a middle party that both buyers and sellers consider to be a trusted entity,such as Taobao and Amazon.But in the feld of data,such authoritative intermediaries are few in number and the excharge fees are extremely high.In order to provide data trade services for buyers and sellers without introducing intermediaries,the openness and reliability of blockchain technology has become a new way to provide data trade services.Data trading schemes based on smart contract emerges.Smart contract is the deployment of a script code that can be triggered automatically in the blockchain network,which is more fexible on the basis of the decentralized and immutability advantages of blockchain.As a result,smart contracts can act as a trusted”middleman” in data trade,controlling the trade process.However,how to guarantee the trade of data as a special commodity without disputes,and how to protect users' privacy in such an P2 P network as blockchain are all challenges that researchers will face.In view of the above problems,this thesis will propose a privacy-preserving,secure and fair data trading scheme based on smart contract.Te main contributions of this thesis are as follows:1.A set of fair data commodity trading scheme based on smart contract is proposed. In this thesis,the whole data trading process is divided into four stages by us- ing smart contract,and a set of fair data trading scheme is designed.Running on a decentralized blockchain network,the solution can automatically interact with buyers and sellers to complete the entire process of data trade without the inter-vention of trusted intermediaries.2.Cryptography is used to protect the privacy of both parties and data in the process of data transaction.On the one hand,in the process of data trade,both parties use anonymous public key addresses in the whole process,and can fnd out the real public key addresses corresponding to anonymous one through tracing if neces-sary,which protects the privacy of the identities of both parties and balances the needs of supervision.On the other hand,encryption is used to protect the privacy of the data and data related information.3.Trail data integrity checking mechanism based on Merkle tree is designed.Since the value of data is not easy to estimate,in the scheme proposed in this thesis,the buyer is given the right to try the trial part of the data and let the buyer decide whether to continue to buy the whole data.In order to achieve the above goals, and to quickly check data integrity and make a judgment in the case of disputes, this thesis designs merkle tree proof and error proof and the verifcation methods by using the merkle tree data structure to ensure the fair conduct of data trade.At the end of this thesis,the security and practicability of this scheme are analyzed,and the cryptography algorithm and the relevant stages of smart contract are tested respectively to verify the correctness and time efciency of the scheme.Cryptographic algorithms involved in the scheme can be completed within 500 ms,the steps of smart contract can also get around 1 s response.In addition,compared with the recent work,the scheme in this thesis has the characteristics of good privacy-preserving,fairness and resistance to malicious behavior.Terefore,the scheme proposed in this thesis can realize secure and fair data transaction in blockchain network.