Research On Secure And Efficient Multi-keyword Ciphertext Search Technology In Cloud Environment

With the rapid development of the Internet of Things,big data and other technologies,localized data storage can no longer meet the needs of businesses.The development of cloud computing technology provides convenient services for data storage and calculation.However,when enterprises or individuals enjoy the convenient services provided by cloud computing,they are also faced with the risk that the outsourced cloud data may be leaked.Since the data outsourced to the cloud server may contain business secrets or personal privacy,the data is encrypted by the data owner before it is outsourced.But encrypting the data,which improves the security of the data,affects the availability of the data,such as the most basic data search function.Therefore,it is necessary to design an effective mechanism to ensure the security and availability of outsourcing cloud data at the same time.Searchable encryption technology is one of an important solution to achieve keyword privacy-preserving search in a cloud environment.This thesis proposes two schemes to solve the problems faced by multi-keyword ranked search in the outsourcing cloud environment:(1)A KGI-index Based Multi-keyword Ranked Search Scheme over Encrypted Cloud Data(KMRS): In this scheme,we propose the keyword grouping inverted index on the basis of traditional inverted index.In this index structure,we generate an posting list for each keyword group.When we use this index structure to perform ciphertext search in the cloud environment,it can well protect the privacy of documents,keywords,indexes,trapdoors,etc.,and improve the security of search.In addition,we improve the search efficiency by using keyword clustering and changing the posting list organized by linear structure into posting list organized by tree structure.Finally,a secure and efficient multi-keyword ciphertext ranked search scheme is proposed.(2)A Based on Document Clustering Verifiable Multi-keyword Ranked Search Scheme over Encrypted Cloud Data(VMRS): Because the cloud servers may have lazy computing problems,this paper proposes a verifiable multi-keyword ranked search scheme based on document clustering.In this scheme,we first cluster the documents,and generate the corresponding two-layer tree index and verification information for the document clusters.During search,the cloud servers only needs to be carried out in the document clusters containing the search keywords,and the lazy computing problem of the cloud servers is detected by means of reconstructing and comparing the verification information.(3)Based on the KMRS scheme,we analyze the specific requirements of the prototype system,and design and implement the prototype system in modules.And we prove that the two schemes we proposed can achieve the secure and efficient multi-keyword ciphertext search function through relevant theoretical support and experimental analysis.