Securing database server using homomorphic encryption and re-encryption

Abstract

A problem with organizations for shifting their storage to cloud or remote server is maintenance of confidentiality, integrity and availability of outsourced data,especially if the remote server is not trusted. Encryption can be used as a solution to these security concerns. But it should be possible for the data owner and other authenticated users of the data to perform queries (especially statistical queries) over data in encrypted domain. Usage of symmetric encryption will create another security concerns like management of key, denying a user from querying data etc. The problem with asymmetric encryption technique is only owner of the data is allowed to decrypt the data with his private key. In this paper we proposed a solution to all these problems by designing an asymmetric fully homomorphic encryption algorithm to encrypt the data. Encryption is done using public key of the owner. So that only owner can decrypt it with his own private key. If owner wants to allow a third party or delegate to perform query over encrypted data then owner will calculate a re-encryption key for him, so that authorized delegates can submit queries to database server and re-encrypt the query result with this re-encryption key so that delegate can decrypt it with his own private key.