Basic Concept of Multilevel Database Security - Multilevel Security for Relational Databases - page 24

User High Trusted DBM Low User

Trusted Operating System

Multilevel
Database

Figure 2.3 Trusted subject architecture.

Table 2.9 Comparison between Polyinstantiation Architectures
CRITERIA MODEL POLYINSTANTIATION TRUSTED DBMS DATABASE FILES PERFORMANCE

No MAC
privileges
architecture

Implicitly Does not

demand trust
in DBMS

Multiple of single
database files

Bad data
retrieval
performance

Trusted subject
architecture

Explicitly Demands trust

in DBMS

Single database
is used to save
data at multiple
security levels

Improved data
retrieval
performance

Table 2.9 gives a comparison between the previous two approaches to
illustrate the advantages and disadvantages of each approach.

2.4 Multilevel Database Security Models

There are many multilevel relational database security models—for
example, SeaView and those proposed by Sandhu-Jajodia, Smith-
Winslett, etc. This section will present an overview of these models
and identify the strengths and the weaknesses of each model.

2.4.1 SeaView Model

In the secure data views (SeaView) model, security levels are assigned
to each data element in the attributes of the tuples in the relation, as
shown in Table 2.7. In the SeaView model, data are stored in a set of
single-level fragments and the multilevel relations are implemented as
views over these single-level relations [24].