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.