Method And Application Research On Searchable Encryption Based On Blockchain

With the rapid development of cloud storage technology,flexible and convenient cloud storage services attract a large number of users to carry out remote storage oper-ations through network services without space restrictions.How to ensure the security of cloud storage has become a hot topic for more and more scholars.The encryption operation of cloud data will lead to the change of the original data index structure,so it is difficult to search and query data based on ciphertext.The emergence of searchable encryption technology has realized how to search based on ciphertext,which plays an im-portant role in protecting the security of cloud storage.At present,searchable encryption technology adopts a centralized solution relying on a trusted third party.Although cloud service providers cannot directly obtain users' privacy data,the centralized service model still has serious problems such as privacy leakage and single point of failure.Block chain,as an emerging distributed trust technology,aims to provide decentralized solutions.This paper mainly studies the application of block chain in ciphertext retrieval.The main re-search work includes the following aspects:(1)Aiming at the problem of data privacy leakage in existing blockchain-based file storage solutions,a distributed storage framework for privacy protection based on blockchain is proposed.The framework is based on the blockchain technology to design a transaction account split method,by reducing the correlation between the transaction account data and the user,to avoid malicious attackers from the privacy analysis caused by the correlation analysis of the transaction data on the chain.At the same time,the framework has an incentive mechanism to join the blockchain on the basis of the interstellar file system to encourage users to share their free storage space in an economic way.Cloud service providers no longer undertake storage functions,but transfer their functions to The storage provider can provide data integrity verification through the key information cloud server stored in the blockchain,and save the verification results on the blockchain to meet the decentralized requirements of file storage.(2)Aiming at the centralization of traditional ciphertext retrieval system,a multi-keyword query scheme for encrypted cloud data based on blockchain and IPFS is proposed.In the scenario of a single cloud service provider,the scheme uses Ethereum as a blockchain for file verification storage,stores encrypted data on IPFS,and retrieves ciphertext by using a secure KNN algorithm.In the scenario of a multi-cloud ser-vice provider,the scheme designs a double-layer blockchain ciphertext retrieval model based on public chain + consortium chain.The public chain only stores the Merkel tree roots constructed from documents,document content addresses and ha The hope value is stored in the alliance chain ledger,and the storage speed is im-proved by hierarchical storage of data.In both scenarios,the cloud server no longer provides storage functions.It is only responsible for storing encrypted indexes and calculating the product of trapdoors and indexes,and by applying the tamper-proof features of the blockchain to the ciphertext retrieval scheme,the query results are returned.Verification to ensure the authenticity of the returned data.