Research On Search And Verification Methods For Cloud Data Sharing

Nowadays,data outsourcing to the cloud has attracted much attention,and users have increasingly higher requirements for the security of private data stored in the cloud.Searchable encryption technology provides a good solution to the data privacy problems caused by cloud shared data.Most of the current research work is limited to single-user scenarios,which cannot meet the needs of multi-user data sharing;in addition,any user in the cloud environment can retrieve files based on keywords,and files involving confidentiality need to be set up for permission control.Regarding the above-mentioned problems,this article starts from the multi-user searchable data sharing requirements,conducts an in-depth study of the existing schemes,and designs a searchable encryption scheme that is more in line with the cloud environment.The chief research content is as below:1)Aiming at the problems of secure search and low efficiency of data in searchable encryption schemes for the multi-user application spectacle,as well as considering the needs of independent authorization by data users,a fuzzy multi-keyword sorting search scheme in the spectacle of multiple data owners is designed.Firstly,construct a fuzzy keyword set based on the wildcard method,and encrypt it according to the corresponding encryption algorithm;secondly,use the vector space model to calculate the correlation score between the file and the fuzzy keywords to achieve efficient sorting and search;finally,the analysis of the security and efficiency shows that this scheme can guarantee the privacy of search results,and under the Decisional Diffie-Hellman Problem,meet the indistinguishability of ciphertext under the attack of selected keywords.2)Based on the improved Merkle-Tree authentication method,a multi-keyword search scheme is proposed.Aiming at the problems of complex search results verification methods,high cost,and low efficiency in existing research work;firstly,use the security features of bilinear mapping to design efficient and accurate multi-keyword search algorithms;secondly,based on Bawa's improved Merkle-Tree authentication method constructs the verification and dynamic update algorithm of the search scheme,which reduces the calculation cost O(n)of the classic Merkle Hash Tree to O(logn),and prevents data tampering,deletion and forgery and other illegal operations.finally,under the assumption of difficult problems,the security of the scheme is analyzed.3)In practical applications,files involving confidentiality need to be retrieved by a certain authorized user.Existing research work generally has problems such as key leakage,inflexible access structure,and inability to support attribute revocation.Aiming at the above problems,a searchable solution with attribute blinding and supporting attribute revocation is proposed.Firstly,by randomly blinding the attributes of data users,aggregate them into a complete blind attribute to realize the privacy protection of data users;secondly,construct efficient fine-grained access control based on Yin's improved attribute encryption based on ciphertext strategy Search;Finally,the correctness analysis and safety analysis of the scheme show that our scheme has certain advantages in safety and function compared with Yin's scheme.