Database Reference
In-Depth Information
3
i
MpleMentation
of
Mls/
DbMs M
oDels
3.1 Introduction
The goal of multilevel security (MLS) for a relational database is to
prevent the unauthorized access of the data by preventing any user from
accessing any data to which he has no access. A lot of multilevel security
database management system (DBMS) models have been proposed to
apply the concept of multilevel security for the relational database.
This chapter will illustrate the implementation of the multilevel
security database management systems (MLS/DBMS) models. Also,
this chapter will provide the flow charts that explain the procedure of
implementing data manipulation language (DML) operations such
as SELECT, INSERT, UPDATE, and DELETE for each model of
the MLS/DBMS models.
3.2 SeaView Model
3.2.1 Selected Operation Procedure
The SQL command for the selected operation is described as follows:
SELECT [A
1
,A
2
,...,A
n
]
FROM R
WHERE P
where R is a multilevel security relation, [
A
1
,A
2
,...,A
n
] are the
attributes of the relation R, and P is the condition of the select state-
ment that defines the tuples to be retrieved. If a user with a security
class level L executes a command to select tuples from an MLS rela-
tion R, the selection operation is implemented as follows [30]:
• Step 1: get the security class level of the user that runs the
select operation.
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