Research On The Privacy Protection Mechanism Of Blockchain Transaction And Its Application

As a distributed shared ledger technology,blockchain has the characteristics of decentralization,non-tampering,traceability,collective maintenance,openness and transparency.Without relying on a third-party trusted institution,it can realize the reliable value transfer between parties who do not trust each other.So it has been widely used in various fields such as finance,supply chain,government affairs,and medical care.However,the openness of the blockchain also brings privacy security issues.All account assets and historical transactions are disclosed on the chain.Although the blockchain adopts a pseudonym mechanism to protect user privacy to a certain extent,with the increase of the number of user transactions,attackers may still find connections between different transactions of users through cluster analysis and other means,thus posing a threat to user privacy.Therefore,how to realize the privacy protection of transactions on the premise of ensuring the verifiability of transactions has become a major challenge in the development and application of blockchain technology.In recent years,the development of the Internet has promoted the rapid growth of the e-commerce industry.While e-commerce facilitates consumers’ life,it also brings unprecedented challenges to the security of consumers’ personal information.Issues related to personal information leakage,random collection,illegal acquisition,excessive use,and illegal trading have become increasingly prominent.The security of traditional centralized e-commerce platforms has become a hot and difficult point in the field of e-commerce.Blockchain can solve this problem by virtue of its decentralized and trustless characteristics.With the help of blockchain technology,procedures can be reduced and payment costs can be reduced;network data security can be improved to protect user privacy;transaction transparency can be improved to facilitate credit construction.In view of the needs of fair exchange and privacy protection in e-commerce transactions,the thesis studies how to realize fair and private commodity transactions based on blockchain under the premise of ensuring transaction verifiability.It has important application value for protecting the personal privacy and legitimate rights and interests of users,and promoting the healthy development of the e-commerce industry.Based on the analysis and study of the existing blockchain privacy protection schemes and related cryptography technologies,this thesis designs an account model blockchain privacy protection scheme based on anonymous custody.And it is applied to e-commerce scenarios combined with the characteristics of e-commerce transactions and privacy protection needs.The main work of this thesis is as follows:(1)To solve the problem that the existing privacy-preserving schemes for account-model blockchain have high transaction cost and low efficiency while fully protecting of identities of both parties,account balance and transaction amount,a privacy-preserving scheme for account-model blockchain based on anonymous custody is proposed.Smart contract is used to provide anonymous fund custody services,which realizes the anonymity of both parties;homomorphic encryption is used to achieve the confidentiality of account balances and transaction amounts,and range proof is introduced to ensure the validity of the encrypted amount;zero-knowledge proof is used to ensure the legality of transactions.Security analysis shows that the proposed scheme satisfies anonymity,confidentiality,balance,anti-theft,and can resist denial of service attacks and sybil attacks.Performance analysis shows that the proposed scheme has high efficiency while fully protecting the privacy of transaction identity and amount.(2)Aiming at the problems of transaction opacity and privacy leakage in traditional e-commerce platforms,combined with the privacy protection scheme proposed in(1),a blockchain-based privacy-preserving scheme for fair commodity transactions is designed.Ensure transaction transparency by recording all buyer and seller transactions on the blockchain.Smart contract is used to escrow funds and perform a blind signature.The buyer sends the unblinded original signature to the seller,and the seller redeems the funds with the signature,thus ensure the privacy of both parties’ identities and transaction content;Smart contract is used to perform a verifiable encrypted signature,thus ensure that the seller will only deliver the goods after confirming that the buyer has paid,and the buyer will only pay after confirming receipt of the goods.When there is a dispute in the transaction,the authority can resolve the dispute to ensure the fairness of the transaction.Through the experimental evaluation on Ethereum,the scheme can realize the function of commodity trading on the blockchain,and effectively ensure the fairness and privacy of commodity trading.