RESEARCH METHODOLOGY AND SYSTEM ANALYSIS: COMPUTER SECURITY SYSTEM USING DATA ENCRYPTION AND DECRYPTION

CHAPTER THREE: RESEARCH METHODOLOGY AND SYSTEM ANALYSIS

3.0.0 REQUIREMENT ANALYSIS

Requirement analysis is the process of understanding the user’s needs and expectations from a proposed system or application. It is one of the most important phases in software development. Determination of client’s need is the major objective of this analysis. Requirements are a description of how a system should behave or description of system properties or attributes. It can alternatively be a statement of ‘what’ an application is expected to do. Inadequate attention to software requirements analysis at the beginning of a software development is the most common cause for initially vulnerable software that often do not deliver even on the basic tasks for which they were designed. There are instances of corporations that have spent huge amounts on software project where the end application eventually does not perform the tasks it was intended for.

The software requirements for this project research among others include:

·               The ability of the software to accept the user inputs i.e. username/password.

·               The ability of the system to allow user to select file to encrypt.

·               The capability to allow user to enter the encryption key on each file for encrypt and decrypt.

·               Presentation of the system to users in interactive mode.
3.1.0     FACTS FINDING METHODS USED

This section is bent on examining the method adopted in data collection, the procedure for data collection and the method used in processing the data collected With respect to this project work, the sources of information/data gathered were:

·                  Observation method

·                  Face to face interview

·                  Internet

3.1.1        Observation method: This is a process whereby the researcher employs a systematic watching and recording of events as they occur. The researcher must be patience and must not be in a time limit because of the study.This method was used to discover what goes on in protecting computer files. 

3.1.2         Face to face interview: This is also another method of data collection. Here, the researcher will have respondent thereby getting the information he/she needs. Data here is more reliable compared with others because the researcher will get those information that are absolute on secret normal, the researcher also adopts his method of selecting the data to avoid bias. Some computer users were interviewed to share their experience so far.

3.1.3        Internet:This is where relevant information on the subject matter was surfed and collected.

3.2.0     SYSTEM ANALYSIS

Computers are fast becoming our way of life and one cannot imagine life without computers in today’s world. You go to a railway station for reservation. You want a website for a cinema ticket, you go to a library, or you go to a bank, you will find computers are used in every possible field today; it becomes an important issue to understand and build these computerized systems in an effective way. Building such systems is not an easy process but requires certain skills and capabilities to understand and follow a systematic procedure towards making of any information system. For this, experts in the field have devised various methodologies. For anyone who is a part of this vast and growing information technology industry, having basic understanding of the development process is essential.

Analysis is a technique that helps to describe an obtained fact and detect its pattern. To properly uncover the entire process in the development of this system, discussion was broken down into smaller units.

Cryptographic is the most effective computer security tool.Cryptography (or cryptology) is the practice and study of hiding secret information by encryption. Encryption and decryption are both methods used to ensure the secure passing of messages and other sensitive documents and information. Encryption is the conversion of data into a form, called a ciphertext. Decryption is the reverse, moving from the unintelligible ciphertext back to plaintext. In other word, Decryption is the process of converting encrypted data back into its original form, so it can be understood.

In order to easily recover the contents of an encrypted signal, the correct decryption key is required. The data to be encrypt is read from the file as byte and stored in decrypted file with extension .EKUMA, eg( filename.EKUMA).  During decryption process, the decrypted data is read, and convert to the original text format before encryption.

Ciphers are the secret codes used to encrypt plaintext messages. Ciphers of various types have been devised, but all of them are either substitution or transposition ciphers. Computer ciphers are ciphers that are used for digital messages. Computer ciphers differ from ordinary substitution and transposition ciphers in that a computer application performs the encryption of data. The term cryptography is sometimes restricted to the use of ciphers or to methods involving the substitution of other letters or symbols for the original letters of a message. The figure below illustrate data encryption and decryption across a network between Alice and Bob.
 
Figure 3.1: data encryption and decryption across a network


When Alice encrypt and send ciphertext across a network to Bob, the encryption key will have to be shared to enable Bob to decrypt the ciphertext. If Bob enters the wrong key he will not have the intended message from Alice.

3.2.1   The Elements of Encryption


There are many different ways that you can use a computer to encrypt or decrypt information. Nevertheless, each of these so-called encryption systems shares common elements:


ü  Encryption algorithm: The encryption algorithm is the function, usually with some mathematical functions, which performs the task of encrypting and decrypting your data.


ü  Encryption keys: Encryption keys are used by the encryption algorithm to determine how data is encrypted or decrypted. Keys are similar to computer passwords: when a piece of information is encrypted, you need to specify the correct key to access it again.

ü  Key length: As with passwords, encryption keys have a predetermined length. Longer keys are more difficult for an attacker to guess than shorter ones because there are more of them to try in a brute-force attack. Different encryption systems allow you to use keys of different lengths; some allow you to use variable-length keys.

ü  Plaintext: The information which you wish to encrypt.

ü  Ciphertext: The information after it is encrypted.

3.2.2    What You Can Do with Encryption


Encryption can play a very important role in your day-to-day computing and communicating:

·         Encryption can protect information stored on your computer from unauthorized access - even from people who otherwise have access to your computer system.

·         Encryption can protect information while it is in transit from one computer system to another.

·         Encryption can be used to deter and detect accidental or intentional alterations in your data.

3.3.0    INPUT ANALYSIS

This deals with the process used to feed data to the system for processing. The input to the computer security system is usually supplied during the use of the program. Data analysis of this computer security system was based on the data gathered from the different approaches mentioned in previous section. Facts were critically elicited from expert sources and used in the development of this system.

3.4.0     OUTPUT ANALYSIS

This involves the resultant transformation generated after processing of files/information supplied. The expected output which every user of the software will look out for is:

·         Generated cipher text for each selected file.

 

3.5.0     SYSTEM SPECIFICATION

Bearing in mind that the actual problem the system is going to solve is to be able to transform plain text into cipher text, proper specification of the object used in the development of the project can go a long way in making sure the goal is achieved. Specification is a means through which the user of the software and the software designer communicate with each other understandably.

3.5.1   Main Menu Specification

The main menu form serves as the center point to all other forms in the system. It comprises of menus and submenu used to display another form or run procedure on any click event. The main menu form includes the file menu, key, encode, folder lock and help menu.

The submenus under file menu include: Select, view, open, property and exit.

Submenu under help menu: About.

3.5.2     Input Specification

The input specification for the computer security: data encryption and decryption system handles all the essential measures which users must take to protect secret sensitive file from unauthorized view.  As a matter of fact in this work, the user only has to login, then select file to encrypt/decrypt from the file menu on the main form. The table 3.1 below is the specification of the controls used in the login form.

Table 3.1: Login Form Specification



S/N

OBJECT

PROPERTY

SETTING/VALUE

1

Form1

Name

caption

frmLogin

LOGIN

2

Label1

Name

caption

lblInfo

enter username and password to access the system.

3

Label2

Name

caption

Lbluser

Username

4

Label3

Name

caption

Lblpass

Password

5

Textbox1

Name

Text

Txtusername

(blank)

6

Textbox2

Name

Text

Txtpassword

(blank)

7

Command1

Name

Caption

CmdOk

Ok

8

Command2

Name

Caption

cmdCancel

Cancel

9

Adodc

Name

adopassword

Table 3.2: Encryption and decryption form specification



S/N

OBJECT

PROPERTY

SETTING/VALUE

1

Form1

Name

Capture

frmMain

Data encryption and decryption

2

Image1

Name

Stretch

imgIcon

True

3

Label1

Name

Capture

lblName

File Name

4

Label2

Name

Capture

lblFileName

{blank}

5

Label3

Name

Capture

lblStatus

Status

6

Label4

Name

Capture

lblVersion

{blank}

7

Label5

Name

Capture

lblSize1

File Size

8

Label6

Name

Capture

lblSize

{blank}

9

Label7

Name

Capture

lblETime

Estimated conversion time

10

Label8

Name

Capture

lblTime

{blank}

11

Label9

Name

Capture

lblPath

File Path

12

Label10

Name

Capture

lblSource

{blank}

13

Line1

Name

linVertical

14

Line2

Name

linHorizontal

15

Commom dialog1

Name

Comdlg

16

Image1

Name

imgFlash

17

Imagelist

Name

Imagelist1

18

Time1

Name

Interval

timTitle

500

19

Time2

Name

Interval

timImgFlash

1300

20

Time3

Name

Interval

timAck

5000

3.5.3    Output Specification

The output specification was based on the operation obtained after the user might have input file either in the encryption or decryption operation. The output enables or leads users to where to save the result of the operation.

3.6.0   STRUCTURED DATA FLOW DIAGRAM OF COMPUTER SECURITY: DATA ENCRYPTION AND DECRYPTION.

            The essence for the system specification is to use a data flow diagram to depict what actually happens as the computer file navigates from one point to another within the system under review. The data flow diagram (DFD) reduces the ambiguity in the original specification.

 


Figure 3.2: Data Flow Diagram of computer security: data encryption and decryption system
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