ABSTRACT
This chapter presents the concept of the encryption-based multilevel model for relational database management systems (DBMS). This model is a combination of the multilevel relation model and an encryption system. The encryption system is used to encrypt each tuple (row) in the relation (table) with an encryption key that depends on the security level of the tuple (tuple classification). The encryption-based multilevel security (MLS) model is characterized by three achievements: 1. Utilizing an encryption system as an additional security layer
over the multilevel security layer for the relational database 2. Reducing the multilevel database size 3. Improving the response time of data retrieval from the multi-
level database Also, this chapter summarizes the efforts of implementing a work-
ing multilevel relational database security prototype. This prototype is used as a research tool for studying principles and mechanisms of the encryption-based multilevel model and other multilevel relational database security models (SeaView, Jajodia-Sandhu, Smith-Winslett, multilevel relational [MLR], and belief-consistent models) [60]. The prototype that is implemented is used to make various experiments to determine the relative performance of the multilevel relational database security models and the performance cost for applying the encryption system in multilevel relational database security.
