Research On Fuzzy Search And Access Control Over Encrypted Data In Cloud Storage

With the rapid development of information technology,people's data has increased exponentially,traditional local storage cannot meet people's demand for data storage and management.Cloud Storage provides centralized management and storage services for data by 'cloud' to users,and for the advantage of convenient and efficient,dynamic and easy to expand,cheap pay-on-demand,more and more companies and individuals upload their data to cloud storage.These data are often private,so people encrypt the data before upload to achieve privacy data protection and use restrictions.Encrypted data can effectively protect privacy and security,and it also brings a series of challenges.When people need to download their document,they hope that the cloud server can search for the document containing the specified keywords in the large-scale encrypted data.In order to improve the search accuracy,the cloud server needs to support multiple keyword search,and can also return the search results in order of relevance.For the input errors that often occur in actual search,fuzzy search needs to be supported.The encrypted data also needs to be shared between multiple data owners and multiple searchers,fine-grained search authorization is required to achieve privacy protection.In order to solve these problems,this paper researches on ciphertext search technology and ciphertext access control technology,proposes two specific ciphertext search schemes to achieve efficient search while ensuring data security.The main works of this paper are organized as follows:First,propose a multi-keyword fuzzy search algorithm over encrypted data,uses Bloom filter and p-stable distribution local-sensitive hashing to build file index and search trapdoor,uses Euclidean metric to measure the distance between fuzzy words.During the search phase,achieve multi-keyword matching by computing vector inner product,and the search results with high correlation are returned to improve the accuracy.The algorithm has better performance on the space efficiency and the time efficiency.Second,propose a fuzzy search scheme based on pinyin similarity over encrypted data in cloud storage,realizing a fuzzy search of multiple Chinese keywords over encrypted data.For Chinese characteristics,there is no need to construct a fuzzy word set in advance,the distance between the fuzzy word and the original word is measured by the pinyin similarity.The scheme uses Bloom filter and p-stable distribution local-sensitive hashing to achieve fuzzy searching.Security and performance analysis with experimental data show that,the proposed scheme not only security,but also effectively decrease the storage cost and perform well at searchThird,propose a search scheme that supports authorized search over encrypted data in cloud storage,realizing a fine-grained search authorization for cipher text.For the case of multiple data owners and multiple search users in the practical application scenario,the schema uses a third-party authority for key generation and distribution.Meanwhile,the schema combining symmetric encryption algorithm and CP-ABE algorithm to achieve document-level access control and protect data privacy.Security analysis and performance simulation experimental results show that the proposed scheme performs well at security,functionality and search.