Database Reference
In-Depth Information
6.2 The Encryption-Based Multilevel Model for DBMS Definition
6.2.1 MLR Model Definition
Definition 6.2.1.1: A multilevel relational database scheme is defined
in the following form [76]:
•
R
(
A
1
,
C
1
,
A
2
,
C
2
, …,
A
n
,
C
n
,
TC
), where
A
i
is the attribute
that stores the data,
C
i
is the attribute that stores the secu-
rity classification level of the attribute
A
i
,
and
TC
is the attri-
bute that stores the security classification level of the tuple.
he domain of the value of the attribute
C
i
is defined by a
set {
L
i
, …,
H
i
} where the
L
i
is the lowest security classifica-
tion level and the
H
i
is the highest security classification level.
The domain of the
TC
is defined as
, where
UL H
n
({
,... ,
)
i
=
i
i
U
stands for the set of union.
Definition 6.2.1.2: The multilevel relational database instance is
defined in the following form [76]:
•
r
(
A
1
,
C
1
,
A
2
,
C
2
, …,
A
n
,
C
n
,
TC
), where
r
is a group of some
tuples that have the values (
a
1
,
c
1
,
a
2
,
c
2
, …,
a
n
,
c
n
,
tc
), where
the value of
a
i
∈
D
i
and the value of
c
i
∈ {
L
i
, …,
H
i
}, or
a
1
=
null
and
c
i
∈ {
L
i
, …,
H
i
} U
null
, and
tc
≥ lub {
c
i
•
c
i
≠
null
:
i
= 1…,
n
}; lub stands for the least upper bound.
Definition 6.2.1.3: The relational database is a set of related rela-
tions and the database state is a set of all the relation instances of the
relational database at a specific time [76].
• The instance
r
(
A
1
,
C
1
,
A
2
,
C
2
, …,
A
n
,
C
n
,
TC
) has some
definitions that will be described as follows:
• The primary key
A
1
and its security classification level
attribute
C
1
:
−
t[A
1
, C
1
]
defines the tuple in the relation instance
r
and also defines the security classification level of
the tuple.
−
t[C
1
] = c
1
means that the tuple is inserted into the
relational database by a user with
c
1
security classifica-
tion level.
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