Abstract
In this paper, we propose an encryption-based multilevel model for database management systems. The proposed model is a combination of the Multilevel Relational (MLR) model and an encryption system. This encryption system encrypts each data in the tuple with different field-key according to a security class of the data element. Each field is decrypted individually by the field-key of which security class is higher than or equal to that of the encrypted field-key. The proposed model is characterized by three achievements: (1) utilizing an encryption system as an additional security layer over the multilevel security layer for the database, (2) reducing the multilevel database size, and (3) improving the response time of the data retrieval from the multilevel database. Also this paper summarizes our efforts in implementing a working multilevel secure database prototype. This prototype is used as a research tool for studying principles and mechanisms of the encryption-based multilevel model and multilevel secure database (MLS/DBMS) models (SeaView, Jajodia-Sandhu, Smith-Winslett, MLR, and Belief-Consistent. Model). This prototype is implemented to be used to perform a series of experiments to measure the performance cost for applying encryption in multilevel database security. (C) 2012 Elsevier Ltd. All rights reserved.