Security And Integrity
After Reading the concepts of database recovery in the last section, let us now deal with a vital concept that helps in minimizing consistency errors in database systems. These are the concepts of database integrity and security.
Information security is the protection of information against unauthorised disclosure, destruction or alteration. Database security is the protection of information that is keeps in a database. It deals with ensuring only the "right people" get the right to access the "right data". By right people we mean those people who have the right to update / access the data that they are requesting to update / access with the database.
This should also make sure the confidentiality of the data. For instance, in an educational institution, information about a student's grades should be made available only to that student, while only the university authorities should be able to update that information. Likewise, personal information of the employees should be accessible only to the authorities concerned and not to everyone. Another instance can be the medical records of patients in a hospital. These should be available only to health care officials.
Therefore, one of the concepts of database security is primarily a specification of access rules about who has what type of access to what information. This is also called as the problem of Authorisation. These access rules are defined at the time database is described. The person who writes access rules is known as the authoriser. The process of guaranteed that information and other protected objects are accessed only in authorised ways is known as access control. There may be other forms of security relating to operating system, physical, communication aspects of databases. Though, in this unit, we will confine ourselves mainly to authorisation and access control using easy commands.
The term integrity is also applied to data and to the mechanism that helps to make sure its consistency. Integrity shows to the avoidance of accidental loss of consistency. Protection of database contents from unauthorised access contains legal and ethical issues, organization policies and database management policies. To protect database various levels of security measures are maintained:
1) Physical: The site or sites having the computer system must be physically secured against illegal entry of unauthorised persons.
2) Human: An approval is given to a user to decrease the chance of any information leakage and unwanted manipulations.
3) Operating System: Even though foolproof security methods are taken to secure database systems, weakness in the operating system security might serve as a means of unauthorised access to the database.
4) Network: Since databases permit distributed or remote access by terminals or network, software level security within the network software is a main issue.
5) Database system: The data items in a database require a fine level of access control. For instance, a user may only be permitted to read a data item and is permitted to issue queries but would not be permitted to deliberately change the data. It is the responsibility of the database system to make sure that these access restrictions are not violated.
To make sure database security needs implementation of security at all the levels as above. The Database Administrator (DBA) is responsible for executing the database security policies in a database system. The organisation or data owners make these policies. DBA makes or cancels the user accounts assigning appropriate security rights to user accounts as well as power of granting and revoking certain privileges further to other users.