Encryption-Based Multilevel Model for DBMS - Multilevel Security for Relational Databases - page 98

C i = L(user)

K = K Ci

Set i = 1

i = i + 1

t i [TC] = L(user)

No

Ye s

t i = D (K, E (K, t i ))

No

t i satisfy P

Ye s

t i [PK] ∈ [A i ]*

No Ye s

Update t i

t i [TC] ≥ L(user)

Ye s No

Update t' i

Display t'i i

End

Figure 5.4 Flow chart for the update operation in the encryption-based multilevel database
model. (N. Kaur, R. Singh, and H. S. Saini. 2009. Proceedings of IEEE International Advance Computing
Conference (IACC 2009) Patiala, India, 1400-1404.)

After tuple t is constructed, the following procedure will be applied:

• If there is a tuple that has a primary key equal to the primary
key of the constructed tuple and its security class level is equal to
the security class level of the user who executes the UPLEVEL
statement, this tuple will be replaced by the constructed tuple;
otherwise, the tuple will be added to the relation.

Figure 5.5 illustrates the flow chart for the uplevel operation in the
encryption-based multilevel database model.