Research On Cryptographic Retrieval Technology For Outsourcing Data In Cloud Computing

With the development of cloud computing,in order to avoid tedious local data management and obtain better service,data outsourcing storage has become an inevitable trend.However,attacks against cloud outsourced data are also emerging,such as the cloud server's "honest but curious" attribute poses a significant threat to outsourcing data.To ensure data security and user privacy,many companies and users store data in a cloud server in the form of ciphertext.Therefore,it is of great importance how to efficiently and comprehensively search cloud-encrypted data without decryption..In order to provide functions of data encryption,controllable sharing and flexible and efficient ciphertext retrieval function for companies and users,and paper realizes the protection of outsourced data from the aspects of outsourcing data preprocessing,index construction and data encryption.From the aspects of similarity,semantic expansion two aspects to achieve based on the keyword ciphertext search function.The main research contents are as follows:1.Adopting the improved method of TF-IDF which adds the word span and position weight to extract the key words,and then set up the inverted index of adding virtual keywords so that malicious attacks cannot easily infer the index content;According to the privacy protection of outsourced data,we use the probabilistic public-key encryption algorithm to encrypt the plaintext,and prove that the algorithm is semantically secure against internal and external attacks.2.A multi-keyword ranked ciphertext retrieval scheme based on semantic extension is proposed.Apriori algorithm is used to mine the co-occurrence relationship between words and find the keyword sets that meet the minimum support threshold to improve the recall of the search results.The trapdoor calculation uses a hash anti-collision function and verifies that no attacker can generate the same hash value on two different inputs.3.A multi-keyword ranking ciphertext retrieval scheme based on similarity is proposed.The query vector is used to locate its document id.The cloud server calculates the relevance score vector in the trapdoor and the TF-IDF value in the cloud index to obtain the similarity set.And returns the top-k ciphertext collection to the user to decrypt,and verify the data integrity.