Research And Implementation On Privacy-Preserving Query For Cloud Outsource Data

With the rapid development of Internet technology,cloud computing has quickly become the favor of IT companies in recent years.Many cloud service providers provide users with kinds of resources and services whose charge is cheap.So,more and more companies tend to consign business and services to the cloud service provider.However,there exists possibility of privacy problems when users store their sensitive data in the cloud server which could not fully trust.To solve this problem,searchable encryption came into being,and has become the current research hotspot.Based on the analysis of the current research results of searchable encryption,the paper put forward a kind of privacy protection range query method for numeric data for existing defects from others.At the same time,the paper improve character data encryption method.And based on the method,this paper put forward a topk retrieval method by way of sampling interval mapping.The privacy-preserving query method of this paper can effectively deal with the attacks from frequency attacks,password analysis attacks,order analysis attacks and so on,reduceing the possibility of a cloud server to obtain users' privacy data.In this paper,the research work includes the following three aspects:(1)Compare and determine our cloud outsourcing data encryption mechanism.In combination with predecessors' results of searchable encryption,to solve the problems on retrieve control such as range control,and determine to use symmetric searchable encryption to solve data privacy protection query problem in cloud.(2)Design a new symmetric encryption solution for character data and numerical data.The paper put forward an encryption method based on sha-1 and vigenere encryption method for encrypting character data,improving the intensity of keyword encryption.The paper also put forward an encryption method supporting range query for numeric data,making cloud server implement range control function on ciphertext.The results of the experiment show that,this encryption method can effectively resist frequency attacks,password analysis attacks and other common attacks in cloud environment,and ensure good performance at the same time.(3)Based on the range query encryption method,the paper put forward a retrieval method of topk privacy protection based on sampling interval mapping.With considerating factors of interval weight,index distribution,query frequency and so on,the method runs on the trusted proxy server,and changes k value to a range by sampling interval mapping table which comes form initial mapping table.So the method converts topk query to non-ordering range query.At the same time,we give semi-automatic maintenance method of mapping table for the method,and prove the effectiveness by experiment.