Research On Blockchain Privacy Protection Scheme Based On Mixing Technology

In recent years,blockchain technology has become one of the most popular technologies.Its decentralized,tamper-resistant,traceable,and public features ensure that distributed storage and transactions can be completed without the involvement of thirdparty institutions.However,the leakage of identity privacy and transaction data privacy in blockchain has become the biggest factor limiting its widespread application.In the most mature application of blockchain technology,cryptocurrency(especially Bitcoin),the disclosure of information on its global ledger results in users’ transactions being linkable and transaction data information being exposed,and analyzing technologies such as public ledgers may lead to the anonymization of user identities.The existing blockchain privacy protection schemes have the following problems:(1)a trusted third party is required,and the decentralized nature of blockchain is weakened;(2)When applied to cryptocurrency,it lacks compatibility with the standard structure of cryptocurrency based on blockchain technology and is not suitable for most cryptocurrency structures(such as Bitcoin);(3)Poor performance in terms of speed or storage results in the solution not being practical.Aiming at these three problems,this paper improves the existing anonymous communication scheme and designs a mixing scheme for blockchain based on the improved anonymous communication scheme to ensure the unlinkage of transactions,so as to solve the problem of identity privacy disclosure of blockchain.In response to the issue of unprotected data privacy in transactions in mixing schemes,a blockchain privacy protection scheme based on confidential transactions and mixing technology has been further designed to simultaneously address the issues of user identity privacy and transaction data privacy in the blockchain.The main work of this thesis includes the following aspects:1.We improve and extend existing anonymous communication schemes,propose a practical anonymous communication scheme based on the DC-net protocol and propose a mixing scheme suitable for blockchain based on this anonymous communication scheme.Specific contributions include:· The proposed optimized anonymous communication scheme improves three main problems in the DC net protocol.A scheduling sub-algorithm is designed to greatly reduce the probability of collisions.Secondly,to prevent interrupts,an interrupt sub-algorithm is designed to identify malicious attackers,ensuring the robustness of the scheme.Finally,the committee election algorithm effectively improves the practicality of the scheme.· The proposed mixing scheme effectively improves the efficiency of generating privacy transactions in cryptocurrencies,with a linear correlation between communication complexity and the number of users.It performs better than other privacy protection schemes when the number of users participating in the mixing is large.2.We propose a blockchain privacy protection scheme based on confidential transactions and mixing technology for the remaining transaction data privacy issues in the blockchain mixing scheme.Specific contributions include:· This scheme solves two problems arising from the combination of confidential transactions and mixing technology,can effectively ensure the balance of funds in transactions and the verifiability of transactions,and provides users with two privacy properties,namely,non Linkage and confidentiality.· The transaction size generated by this scheme is smaller than the current mainstream scheme,which can effectively reduce transaction costs and is more practical.It also has compatibility and can be applied to other blockchainbased cryptocurrencies.