In the early days of networks the computer networks had a limited use. They were mainly used by researchers for e-mails and employees of an organization for sharing printers and databases. We’d like all important properties safe and sound for a long period of time. With a view to use these properties in future we concentrate on all security arrangement with full attention. In regard to a computer user data stored in the system is an important asset; one can’t just lock it inside one’s briefcase. This security was not as crucial an issue as it is now with the advent of internet a lot of ongoing e-commerce activities across the networks.

It is not possible to provide a perfect security system as the data is transmitted over some medium which makes it vulnerable.