Research On Ciphertext Fuzzy Retrieval Supporting Access Control Under Cloud

With the development of computer technology,the amount of data will continue to grow over time,and the physical storage of data can no longer meet people's needs.Therefore,more and more people upload data to the cloud.However,for security reasons,data is usually encrypted before uploading.The method of encrypting the data and then uploading it to the cloud server achieves the privacy protection of the data to a certain extent,but the corresponding problems arise.When a "cloud" user needs to find a document in encrypted data,they need to first download it to a local physical storage device and query it in clear text.In order to solve this problem,many scholars have made research on searchable encryption.However,traditional searchable encryption can only perform accurate retrieval of ciphertext data,and fails to take into account possible input errors in the actual retrieval process.Therefore,how to perform fuzzy retrieval of ciphertext data has become a new research hotspot.Uploading data to the cloud not only reduces the cost of local physical storage,but also makes it easier to share data.In order to prevent ciphertext data from being acquired by the "enemy",access control should be implemented for ciphertext data retrieval and fine-grained authorized search should be implemented to ensure information security.Aiming at the above problems,this paper makes an in-depth study of ciphertext fuzzy retrieval and access control,and proposes two schemes to realize secure ciphertext fuzzy retrieval that supports multi-user access control in the cloud environment.This paper mainly does the following research work:(1)A fuzzy ciphertext retrieval scheme based on font similarity in cloud environment is proposed.After consulting the existing ciphertext retrieval schemes,it is found that most of the existing ciphertext retrieval schemes are based on word sound similarity,but few of them are based on font similarity.However,some related studies have shown that due to the word-formation characteristics of Chinese characters,there are more misspellings caused by font similarity than phonetic likeness.Therefore,a ciphertext fuzzy retrieval scheme based on font similarity to measure editing distance is proposed in this paper.In the scheme,Chinese characters are converted to glyph coding by reverse use of wubi character coding,and E2 LSH and Blum filter are used to construct security index and safety trap door,so as to realize the glyph similarity as editing distance and quantify the glyph similarity under ciphertext conditions.During the retrieval,multiple keywords can be fuzzy searched simultaneously by inner product matching sorting by security trap door and security index.The matching accuracy is high,and the retrieval has good performance in time and space efficiency.(2)In this paper,according to the requirements of software engineering specifications,a prototype system is implemented for ciphertext fuzzy retrieval scheme based on glyph similarity in cloud.According to the specification of software engineering,the requirement analysis and system design of the scheme are carried out,and the coding implementation is carried out.Finally,the function of the system is tested.(3)This paper proposes a ciphertext retrieval scheme that supports access control for multiple users in the cloud environment.Aiming at the possible information leakage problem in ciphertext retrieval in the case of multi-users sharing in the public cloud environment,this paper proposes a ciphertext fuzzy retrieval scheme that supports access control.The scheme realizes the access control under the condition of multiple data owners through the CP-ABE scheme,and realizes the fine-grained access control for authorized users.Meanwhile,the scheme encryfies the symmetric encryption key again.The scheme in this paper not only retains the performance of ciphertext fuzzy retrieval scheme but also improves the security greatly.