CHAPTER FOUR: SYSTEM DESIGN
4.0.0 SYSTEM
DESIGN
System design is
a very important aspect of a software development. The relationship between the
input and the output is a product of good design. Good interaction between the
end user and the software is the handwork of design: that is, the user
interface aspect of the software. The major output from the software design
phase is the design itself.
Figure
4.1: The Main Menu Design.
4.0.1 User
Interface Design
This software
was developed to enhance interactivity normally required in modern software
development. In short, every window based application has the potential to
create this interaction. Hence, Data encryption and decryption system is not an
exception. Splash screen was used to usher-in the package with meaningful
introductory information displayed on it that helps to explain the application.
The splash screen precedes the login form.
4.0.2 Main
Menu Design
The main menu
design is the window that comes up after the user must have keyed in his/her
username and password. The main menu has major menu items to show which is the
major operations of the system. Some of these menu items have other submenu
items to specifically carryout any desired operations. The main menu is
designed as shown below:
4.1.0 Input
Form Design
The input Form
provides avenue for the user to feed in data or select file into the computer
system. Two input forms were used in the cause of developing this application.
They are: the login form and the enter key Form. Both of them were designed
using controls as textboxes, labels, command buttons and checkboxes. Figure 4.2
and 4.3 below demonstrate how they are designed in this work.
Figure
4.2: Login Form Design.
Figure
4.3: Enter key form design
4.2.0 Database Design
Data encryption
and decryption system has one database tables. The table below has to do with
the login form and its design is shown below as well.
Figure 4.4:
Database Design of the Login Form.
4.3.0 Program Module Design
The menu or
submenu performs a specific function. The integration of all of them makes a
complete program. Subprogram coded for a particular menu can be used to call up
another program menu as the case may be. The computer security: data encryption
and decryption system is designed using top down methodology. Hence, programs are
implemented in modules giving each module a particular task to perform. The
program flowchart of figure 4.5 shows both the architectural design and
detailed design respectively of the entire system.
Figure
4.5: An Architectural Program Flowchart of the Main Menu Design.