Design And Realization Of Fuzzy Searchable Encryption In Cloud Environment

With the popularization and development of cloud computing,more and more companies and individuals have stored data in cloud servers,reducing the cost of time and manpower.Because these data may involve the user's privacy information,it is necessary to use encryption technology to encrypt the data before uploading it to the cloud server to protect the user's privacy.But at this point,the user will encounter the problem of how to find data in the state of the cipher-text,because the processing strategy applicable to the state of the plain-text can not be directly applied to the data under the state of the cipher-text.Searchable encryption is a kind of photographic primitives that support the user to search for keywords in the state of cipher-text and it can meet the needs of finding data on the premise of protecting data privacy.In information retrieval systems,users often have slight typos and inconsistent formats when they input data,so this paper focuses on fuzzy search function to improve the practicability of the system.First,the asymmetric fuzzy searchable encryption scheme based on Paillier encryption algorithm(PFSE)and the symmetric fuzzy searchable encryption scheme based on Secure KNN encryption algorithm(SFSE)are proposed for different application scene types.At present,most of the searchable encryption schemes only support the fuzzy search of English letters or characters in the ASCII code table.By preprocessing the key words,so that the two schemes in this paper can support the fuzzy search of Chinese characters and the search in random order in English,and the function of fuzzy search is more perfect.In addition,the two schemes of this paper use TF-IDF to filter the results of the search,and return only a number of data that are most related to the query keywords each time,which reduces the transmission cost and ensures a good search experience of the user.Secondly,In the search phase,the PFSE scheme compared with the contrast scheme,when the keyword length is 6,the time overhead is reduced by 25%,although the space overhead and time overhead of the PFSE scheme is increased in the initialization stage.But the search phase is the most time-consuming and the search function is the most important function.Therefore,the PFSE scheme is more efficient than the comparison scheme.The experimental comparison scheme leaks part of the key in the search phase,and the PFSE scheme will not leak any key information at all stages after improving the system structure,so the PFSE scheme is more secure.In the SFSE scheme,the index based on inverted index is constructed,which makes the SFSE scheme more efficient and more accurate than the experimental comparison scheme.Finally,we use the keyword extraction algorithm,automatic text summary generation algorithm,the stem extraction algorithm and the form reduction algorithm to optimize the scheme of this paper.In addition,the function of numerical interval fuzzy search in cipher-text state is also realized.