Blockchain-based Anonymous Privacy Protection Scheme And Its Application Research And Implementation In Auction System

With the continuous development of e-commerce and the gradual emergence of the advantages of blockchain technology,a variety of blockchain-based auction platforms have emerged at home and abroad.However,the openness and transparency of the blockchain has seriously threatened user' privacy.The anonymous mechanism provided by the blockchain is actually a so-called pseudonym mechanism,which cannot guarantee true anonymity.Especially in the auction system,the group of user is relatively fixed,the transaction value is relatively high,and the attacker is more likely to analyze the transaction.The attacker will try to analyze the transaction characteristics behind the auction transaction data,and give an identity portrait to the anonymous account.Matching anonymous blockchain addresses with users' real identities has caused serious privacy leaks.Therefore,it is of great significance to study the anonymous privacy protection mechanism of blockchain in the auction scene.In view of this,this article studies the anonymous privacy protection mechanism of the blockchain from the transaction layer and network layers,and implements a blockchain auction system that balances openness and transparency with anonymous privacy.The main work of this article and the innovations are as follows:(1)We design a blind signature coin-mixing scheme based on ECDSA to provide the privacy protection mechanism of the transaction layer.Compared with the previous blind signature coin-mixing scheme,our scheme not only solves the problem of untrustworthiness of traditional coin-mixing service providers,but our scheme also ensures the reliability of participating users,that is,in the coin-mixing process,no matter whether the user or the bank has deceptive behavior,it can be found which ensure good reliability on both sides.Moreover,our scheme allows a deposit transaction to be split into multiple withdrawal transactions.On the basis of inheriting the characteristics of the original mixed currency scheme,our scheme has better anonymous privacy.(2)We design the ABAC model based on Ethereum.Unlike the traditional ABAC model,We integrate PEP and some PAP on the blockchain side,and distribute the attribute manager on the blockchain and database to solve the storage limitation and difficulty of retrieval that rely solely on the blockchain attribute manager.We design a template web page to generate a strategy contract,eliminating the need for resource owners to write code.Access decisions are made through the cooperation of servers,blockchains,and databases,which regulates access to smart contracts and enables more fine-grained access control.(3)We establish a blockchain auction system on the Ethereum platform and complete the core auction process using the Vickery auction method.The ABAC model designed above is introduced to restrict users participating in the auction,prevent users who do not comply with the policy rules from further obtaining private information,and provide a network layer privacy protection mechanism for the anonymous privacy of the blockchain auction system.In the core process of auction(bidding,announcement,and revealing),only commitment payment is involved,and the actual payment is completed in the coin-mixing module.The coin-mixing module is implemented by the coin-mixing scheme based on the ECDSA blind signature,making it impossible for others to guess the true identity of the auctioneer and bidder,and providing a transaction layer privacy protection mechanism for the blockchain auction system.