Security of data

Security problems

The security of data means the protection of data. The term refers to all methods of protecting data and software from being:

lost;
destroyed;
corrupted;
incorrectly modified;
disclosed to someone who should not have access to it.

Data is said to corrupt if errors are introduced into it. Usually the errors have been introduced by faulty equipment.

Danger to files

Files may be in danger of accidently or intentionally being :

1. lost, e.g.

by losing discs;
because the file is on the system but badly named

2. destroyed, e.g.

by fire or flood;
by deletion.

3. corrupted, e.g.

by scratches on a disc or faulty disc drives;
by interference during a communication.

4. modified, e.g.

by being unintentionally written over;
by being updated with incorrect data.

5. accessed by unauthorised people.

Hacking

Hacking means obtaining access to a computer system without authority. Many examples of hackers are

programmers within the company concerned ;
someone from outside that use a modem from their own home computer to connect to the computer being hacked.
someone that gained access to the electronic mailboxes of famous people.

Viruses

A computer virus is a program which copies itself without the user intending it to. Often a virus attaches itself to other programs which are then saved with the virus added to them. Most viruses do not affect data files. The virus usually does more than just copy itself. It may erase files or corrupt the data on the screen.

Viruses cost commercial firms a great deal of money. Even if their computer are not infected, they have to spend money making sure viruses are not introduced. Step they can take are:

make sure everyone in the organisation knows of the danger.
use a commercial program which detects any viruses. Many of these can say which viruses are present and get rid of them.
avoid the used of any programs of doubtful origin, such as 'free' software.
back up files on a regular basis. This may not get rid of the viruses, but if it deletes files, at least they can be recovered.
make standard software write protected, so that a virus cannot change it.

Making copies of files

Data can be protected from destruction or modification by keeping copies, although care has to be taken that this does not make unauthorised access easier. A backup file is a copy of a file which is kept in case anything happens to the original file. An achive is a file or set of files which is being kept in long term storage in case it is required.A backup files may be created by the user or may be produced automatically by the system.

A particular word processor has two automatic backup facilities.

Backup on saving. This is to ensure that when the user saves file the old version is not lost. The old version of the file automatically renamed before saving the new one. The old one is given a name ending in BAK so that the user can easily recognise what it is, e.g. LETTER.BAK is the old version of LETTER.DOC.
Timed backup. This option is useful if there is a power failure. The word processor automatically saves the documents in use every 15 minutes.

Backup files and archives use a large amount of storage. Methods are devised of storing the data in a smaller space. A compression program is run which changes the individual bit p;atterns of the characters as they are being stored so that the data takes up less storage space. The disadvantage of this system is that it takes time to decompress the data again if it is to be used.

Other ways of looking after data

Physical safeguards

1. Locking files away.

To protect against fire, flood or theft, backup files and software are often kept in another building in a fireproof and waterproof safe.
Important data stored on floopy discs should be kept in a safe place.

2. Protecting files against being overwritten

Large magnetic tapes usually have to be fitted with a write permit ring before data can be written on them.
Tape cartridges have a small tab on the edge which can be sbapped off to prevent anyone writting data on the tape.
Tha data on floopy discs can be protected by sliding a small write protect tab.

3. Keeping people out

Only authorised personnel are allowed into certain area of many computer installations.

Software Safeguard

A large computer system or a netword may have many users and many terminals or workstations. Use has to be restricted.

A user identify (ID) ia a name or number by which the system knows that the user. Each user is given an area of backing store in which to store files. Often the user can decide which other users can access these files.

A password is a set of characters which a computer associates with a particular user identify. The password is known only to the user an usually he or she selects it. A password is usually kept secret and the computer does not display it on the screen as it is typed in.

Users of the system with user identities dan passwords have to log in and log out every time they use it. To log in means to gain access to a system by giving the correct instructions and responses. To log out means to exit from a system by giving the correct instructions.

Example of a log in and log out sequence.

Logging in. When you first come to a station a menu asks you which file server you require. You select one using the mouse. A screen appears with spaces for user identify and password. You type these ini. The user identify appears as you type it but the password does not. A main menu then appears for you to select the software you wish to use.

Logging out. When you have finished using s software packages you exit from it. You then return to the main menu. This has an option "Exit from the network" which you can select to log out.

Advice about passwords.

Many hacking problems arise from people finding out passwords or guessing them. Your files are much more secure if you stick to the following rules.

Choose a sequence containing no fewer than six characters.

Pick something you can remember but no-one else would think of, even if they know you.

Never tell anyone what it is.

Never write it down.

Be careful who is looking over your shoulder.

Change it every week or so.

Other software safeguard

Some files may only be accessible to certain password.
On some systems users may be able to give files an access code. For example, a file may be made "read only".
Individual files may be given passwords.
Data encryption. The encrypt data is to encode it in such a way that is unreadable to anyone who does not know how to decode it.

| meningkatkan keupayaan komputer | atasi masalah penjagaan komputer | pengacau virus |