Network Security Philadelphia UniversitylAhmad Al-Ghoul 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  E Address:

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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).

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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

Network Security Philadelphia UniversitylAhmad Al-Ghoul 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.