Research On Multi-keyword Search Over Encryption Data In Cloud Storage

With the rapid development of cloud computing and big data,cloud storage is popular among users or organizations due to its convenience,on-demand service and low cost.Cloud storage is widely used in different fields.Massive data are uploaded to cloud servers in order to save local data storage and management overhead.However,since the cloud server is vulnerable to internal or external attacks,users should encrypt their data before uploading to the cloud server in order to prevent the disclosure of private information.However,some data computing methods in plaintext will not be applicable any more in ciphertext.Therefore,the retrieval of ciphertext data has become a major obstacle to cloud storage services.There is an urgent need for a technology that can both protect data privacy and facilitate users to operate the ciphertext data.Nowadays,many researchers have proposed many ciphertext retrieval schemes,but these schemes still have some shortcomings in aspects of functionality,practicality,high efficiency and security.In this paper,the following research work focus on functionality and practicality of ciphertext retrieval schemes.1.A multi-keyword fuzzy search scheme based on variant coding is proposed.In the research of ciphertext retrieval schemes,one of the main problems is the practicability of the scheme.In our scheme,we build a custom function.Using this custom function,keywords can be converted to code value.The custom function needs to make each letter has the same weight of keywords,so as to make the method solve the problems of missing-letters and exchange-letters in the keyword such as fuzzy search under the predefined threshold,which makes the application range of our method broaden.Secondly,we build an index function for each plaintext file based on the keyword set.In the process of ciphertext search,we match the keyword trapdoor set with the file index function,so as to improve the search efficiency of the scheme.In the whole scheme,we omit the predefined fuzzy keyword set and keyword trapdoor set to reduce the local storage consumption.In addition,the scheme uses the encryption algorithm of multi-attribute authorization agencies to encrypt data,in order to ensure that the private information is not disclosed,and make the scheme be able to resist keyword guessing attacks and collusion attacks among multiple users or among users and the cloud server.It provides security to the scheme.Finally,the simulation tests on this scheme and other comparison schemes based on the actual data set prove the practicability and high efficiency of this scheme.2.A multi-keyword search scheme based on probability trapdoor is proposed.In most existing ciphertext retrieval schemes,the keyword trapdoor is deterministic trapdoor,so the scheme cannot resist indivisibility attack.In this scheme,we construct a keyword probability trapdoor to ensure that the scheme can resist the keyword trapdoor inseparable attack and trapdoor index indistinguishable attack.We also introduce the keyword vector when constructing the keyword trapdoor,so that the scheme can realize multi-keyword search in the process of ciphertext search,and enhance the functionality of the scheme.In addition,we give the correctness and robustness analysis of the scheme,and prove that the scheme can resist indistinguishable attacks,so as to ensure the security of the scheme.Finally,we give the comparison results among this scheme and other ciphertext retrieval schemes,and prove that this scheme has obvious advantages over other schemes in terms of search function and storage complexity.