Security

After studying this section you should be able to:

• define the terms security and integrity
• describe backing-up procedures
• explain how a system can recover from hardware or software failure
• state methods of preventing unauthorised access to online data

Security procedures

Security is provided by introducing procedures and safeguards to ensure that data are not accidentally or maliciously corrupted. If data have not been corrupted they are said to have integrity.

Backups

It is always possible to back up a file by creating another copy, typically on a magnetic tape. This version can be copied again so that three copies are in existence. One of these should be either taken to another location or placed in a fireproof safe as protection against fire.

By backing-up data stored in a computer system regularly, data should never be lost no matter what happens to the computer system.

Encryption

Data can be encrypted to appear garbled unless you know how to decrypt the data. This can prevent unauthorised access as the data will be meaningless.

Encryption can be performed automatically and is a key method of providing a secure connection over the Internet.

Passwords

Passwords can be applied to computer systems so users cannot access the data unless they know the password. Passwords can also be applied to individual files so that a hierarchy of passwords may exist. Passwords should be changed regularly in case they become generally known.

By setting up a hierarchy of passwords different users can be given access to different files or programs.

Virus guards

A virus is a small program that attaches itself to your files. When you use a file with a virus attached it loads itself into the memory of the computer. It is able to replicate itself so that every time a new file is used it attaches itself to that one as well. In this way it can gradually attach itself to all of your files. This would not be much of a problem (except that you are wasting disk space) but a virus may suddenly turn nasty and attack your computer by, for example, removing all the files from your hard drive. Fortunately there are programs that can detect viruses and guard against them (called virus checkers or virus guards). Updates for these programs appear regularly, as new viruses appear all the time.