Analysis and Implementation of a Method Resistant to Functional Dependency Attacks on Databases with Sensitive Records

The technology evolution has helped to develop large database management systems. Certain information due to its importance is qualified as sensitive with the help of security constraints (SC). Basic encryption method (BEM) encrypts sensitive cells in respective sensitive records. But It does not guarantee security because of possible data dependencies between attributes that may be used for functional dependency attack (FDA) with the help of evidence records having the same values of left-hand side attributes of functional dependencies defining right-hand side sensitive cells. Partial encryption method (PEM) in addition to sensitive cells encrypts also some attributes of functional dependences to resist FDA. These methods are investigated in the thesis, and some problems of PEM are revealed (double encryption, absence of ordering of FDs after finding minimal attribute cover (MAC)). Its modification, PEM-M, eliminating double encryption and ordering FDs according to MAC is proposed. Methods PEM and PEM-M are implemented using Windev 17 platform, where a user can load a database with any scheme automatically recognized, define its security constraints and functional dependencies. Then, the methods transform the database to a form resistant to FDA. Implementation was tested on a number of examples. Efficiency of the methods was studied on a benchmark Adults database used originally for testing PEM by their authors. PEM-M was tested in the same way but using Test database. Some experiments were done using 100 and 32K records of Test database in PEM and PEM-M in order to compare efficiency and accuracy to see which method performs better. It appear that in term of execution time, PEM can performs better with scores of 0.311 and 859.13 seconds for 100 and 32K records respectively comparing to 0,345 and 952.55 seconds for PEM-M. But, in term of accuracy, PEM-M performs better with 0% of risk of double encryption which is not the case for PEM. Keywords: Database management system, Security constraint, Sensitive cell, Sensitive record, Basic encryption method, Functional dependency, Functional dependency attack, Evidence record, Partial encryption method.