1. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-20111 Module 7 Module 7 Data Base Security  MModified by :Ahmad Al Ghoul  PPhiladelphia University  FFaculty Of Administrative & Financial Sciences  BBusiness Networking & System Management Department  RRoom Number 32406  EE-mail Address: ahmad4_2_69@hotmail.com

2. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-20112 Contents  Concept of a Data Base  Components of Data Bases  Advantages of Using Data Bases  Security Requirements  Integrity of the Data Base  Element Integrity  Field Checks  Access Control  Change Log

3. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-20113 Concept of a Data Base  Collection of data and a set of rules that organise the data by specifying certain relationships among the data.  The data items are stored in a file  User is not concerned with the precise physical format of the file.  A data base administrator is the person – who defines the rules that organise the data –Controls who should have access to what parts of the data  The user interacts with the database through a program called data base manager or DBMS (front-end).

4. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-20114 Components of Data Bases  The data base file consists of –Records: contains one related group of data –Each record contains fields or elements  A data base can be viewed as a two- dimensional table  The logical structure of a data base is called a schema

5. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-20115 Components of Data Bases  The name of each column is called an attribute of the data base.  A relation is a set of columns.  Users interact with data base managers through commands that retrieve, modify, add or delete fields and records of the data base –Commands are called a query  DBMSs have precise rules of syntax for queries. SELECT NAME = ‘AYŞE’ retrieves all records having the value AYŞE in the NAME field.  The result of executing a query is a subschema

6. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-20116 Advantages of Using Data Bases  Shared access –Many users can use one common, centralised set of data  Min. Redundancy –Individual users do not have to collect and maintain their own sets of data  Consistency –A change to data value affects all users of data value  Integrity –Values are protected against accidental or malicious incorrect changes  Controlled access –Only authorised users are allowed to view or modify data values

7. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-20117 Security Requirements  Physical data base integrity –İmmune to power failures  Logical data base integrity –Structure is preserved  Element integrity –Data contained in each element is correct  Auditibility –Trace who accessed/ modified elements  Access control –User is allowed to access to only authorised data  User authentication –To ensure every user is positively identified  Availability –Users can access the data base in general and all the data for which they are authorised

8. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-20118 Integrity of the Data Base  Trust the accuracy of the data values  Updates are performed only by authorised individuals  Data must be protected from corruption –The whole data base is damaged –Individual data items are unreadable  Integrity of the data base is the responsibility of the DBMS  Periodic back-ups of a data base  DBMS must maintain a log of transactions

9. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-20119 Element Integrity  Authorised users are responsible for putting correct data into the data base –Mistakes in collecting data –Mistakes in computing results –Mistakes in entering data  The DBMS maintains the integrity by: –Applying field checks –Access control –Change log

10. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-201110 Field Checks  Test for appropriate values in a position –Numeric –Uppercase letter –A set of acceptable characters  The check ensures that a value falls within specified bounds or is not greater thatn the sum of the values in two other fields  Prevents simple errors as the data is enetered. 25060

11. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-201111 Access Control  A data base may contain data from different sources –Redundant data might have been stored in many places  Data bases have led to the collection and control of this data at one central source –Who has authorisation to update which elements –Policy issues

12. Network Security Philadelphia UniversitylAhmad Al-Ghoul 2010-201112 Change Log  A list of every change made to the data base  The log contains –Original –Modified values  With this log a data base administrator can undo any changes that were in error.