Abstract:
Nowadays people prefer to concentrate on their own business and outsource the rest of the work. This has brought two important concepts to information technology world. First one is the "Software as a service" and the second one is the "Database as a service". Using "Database as a service" concept made things easier but brought some issues to consider. Independent of the database type (relational, XML or even flat text file) the data kept in un-trusted third parties have to be secured in "database as a service" concept. In order to overcome this security issue, the databases have to be encrypted and the key should not be disclosed to the service provider. Unrevealing the key to database service provider brings another problem which is querying the encrypted database. There are solutions in literature on querying encrypted databases without revealing the key to service provider. Some of these solutions are efficient while some suffer from low response times. First contribution of this paper is proposing a schema which efficiently and securely queries an encrypted XML document. Content of XML document is not revealed to server. Indexes are manipulated by adding bogus data in order to make the schema more secure. Second contribution is parallel processing of query evaluation at service provider side. Proposed model is a unique model in literature in terms of using parallel processing in encrypted XML documents. The response times of the proposed schemas are evaluated and it is shown that the proposed schema is an efficient schema and parallel processing significantly increases the performance in encrypted XML documents.
