Research On Searchable Encryption Algorithm Supporting Multiple Keywords

Due to the advantages of low cost and convenient access,data outsourcing based on cloud computing has become widely popular in recent years.Cloud service providers(CSPs)are usually semi-trusted,which inevitably brings data security and privacy concerns.In order to achieve the privacy and retrievability of outsourced data at the same time,researchers have proposed many searchable encryption schemes,but most of these searchable encryption schemes support single-keyword search,and few of them consider the verifiability of retrieval results.Therefore,on the basis of analyzing the privacy protection requirements of data outsourcing based on cloud computing,this thesis researches the multi-keyword searchable encryption technology.The main work is as follows:Firstly,to solve the problems that the search results of many searchable encryption schemes cannot be sorted or verified,and the update efficiency is too low,an anti-leak dynamic multi-keyword fuzzy search scheme is proposed.Firstly,a secondary index structure is constructed.The first-level index is composed of inverted index and orthogonal list.Combined with 2-gram,Bloom filter and locality-sensitive hash function to realize fuzzy match and efficient data update.The second-level index achieves user search permission decision and search result ranking by combines coordinate matching with Term Frequency-Inverse Document Frequency(TF-IDF).Secondly,a verification token is generated within the results to verify the validity of the search results.The results of security analysis and performance analysis show that this scheme has certain advantages over existing similar schemes in terms of security and performance,and can meet the privacy protection requirements of sensitive data outsourced storage.Secondly,a time-sensitive multi-keyword searchable encryption scheme for multiple data owners is proposed for the application scenarios where some files have ownership sharing attributes and retrieval rights timeliness.The solution supports multi-keyword connection,which further improves the search efficiency.The effective retrieval period is controlled by embedding the time division factor,that is,the file can be retrieved only within a preset period of time.Based on the Lagrangian interpolation method,to realize the multi-owner signature of the file,the retrieval user performs signature verification on the retrieval result to ensure the authenticity and integrity of the result.Finally,the security and efficiency of the scheme are verified through formal analysis and simulation experiments.