Abstract: Cloud computing, individuals can store their data on remote servers and allow data access to public users through the cloud servers. As the outsourced data are likely to contain sensitive privacy information, they are typically encrypted before uploaded to the cloud. This, however, significantly limits the usability of outsourced data due to the difficult of searching over the encrypted data. An efficient search technique for document retrieval from encrypted cloud data is developed. Original contributions are three-fold. First, relevance scores and preference factors are introduced upon keywords which enable the precise keyword search and personalized user experience. Second, a practical and very efficient multi-keyword search scheme is developed . The proposed scheme can support complicated logic search the mixed and “AND”, “OR”, and “NO” operations of keywords. Third, classified sub dictionaries technique is employed to achieve better efficiency on index building, trapdoor generating and query. Lastly, the security of the proposed schemes is analyzed in terms of confidentiality of documents, privacy protection of index and trapdoor, and unlinks ability of trapdoor.

Keywords: Cloud computing, encrypted, confidentiality, trapdoor.