The document describes 6 practical exercises related to computer security: 1. Installing and configuring antivirus software on a system 2. Performing backup and restore on a system 3. Setting passwords for the operating system and applications 4. Applying security permissions to file folders and applications 5. Writing a Python program to implement the Caesar cipher encryption technique 6. Writing a Python program to implement the rail fence encryption technique

1. Practical No 1
Aim : Install and Configure antivirus (any ) on your system.
Software Requirements : Operating System (windows 10), Antivirus (here, Avast
antivirus
).
Procedure :
Here , the following step needed to install and configure antivirus(Avast) on your
system.
1. From the following link you can download it on your system.
 Link : https://www.avast.com/en-in/free-antivirus-download#pc
1.Right-click the downloaded setup file
avast_free_antivirus_setup_online.exe an select
Run as administrater from the context menu.
2. If prompted for permission by the User Account Control dialog, click Yes

2. To change the default setup language, click the current language
in the top-right corner of the screen. Then, click Install to
proceed with default installation, or click Customize if you need
to make changes to the default setup.
To change the default setup language, click the current language in the top-right
corner of the screen. Then, click Install to proceed with default installation, or
click Customize if you need to make changes to the default setup.

3. Wait while setup installs Avast Free Antivirus on your PC.

4. Review the Avast Privacy Policy, and click I Agree if you are happy to share
anonymous user data with Avast and other third-parties. If you do not want to
share user data, click No, Thanks.
Once the installation is complete, click on continue.

5. Click Run First Scan to trigger a comprehensive Smart Scan to detect
viruses, malware, bad browser add-ons, and other issues on your PC.
Result : Thus , I have successfully installed and configured antivirus software
On my system.

6. Practical no 2
Aim : Perform backup and restore on your system.
Software Requirements : Operating system.
Procedure:
Steps to perform backup and restore are as follows:
1. Open the Backup and Restore window from the Control Panel..

7. 2.On the Backup and Restore window, choose the “Create a
system image” option on the left.
3.On the Create a system image window, you can choose where to store
the backup from among three places: your hard disk, on DVD’s, or in the
network.

8. 4.In the next window, just confirm your image settings and click Start backup.
Result : Thus , I have successfully performed backup and restore on my
system.
And ,here your restoration is completed an d your sytem
restored gets successfully.

9. Practical No 3
Aim : Set up password to Operating System and application.
Software Requirement : Operating System(Windows 10), MyLockBox
application (to lock application )
Procedure : 1) The easiest way to do that in Windows 10 is by
executing control from the Start menu or Run dialog box. In
Windows 8, use the Power User Menu by pressing Win+X.

10. 2) Select User Accounts (Windows 10) or User Accounts and Family
Safety (Windows 8).
3) Open User Accounts.
/

11. 4) Choose Make changes to my account in PC settings.
5) Select Sign-in options from the left.

12. 6) Under the Password area, choose Add.
7) In the Password hint field, enter something that will help you remember
the password should you forget it, and then select Next.

13. 8)Hit Finish to complete the new password setup.
9) You can now exit out of any windows you opened to make the password,
like Settings or PC settings.

14.  Steps to set up password for an application are as follows:
 I have used an application called MyLockBox for setting up the
passwordfor an application on my system .
Link : https://my-lockbox.en.lo4d.com/windows

15. 1. After installing , when you open the application for the first time , it will
ask to set the password .You can also provide password hint and email
there.
2. Open the MyLockBox Control panel and it will ask you the location folder
/application you want to protect.
In case you want to protect an application , simply provide the location
of the folder which contains the application executable (.exe file).
You can browse the location for the folder also.
In my case , I want Google Chrome to get password protected.
3. After providing the path of the folder , click Ok.

16. 4.Now your application is successfully lock and at the time of opening the
application ,the error will be pop-up as shown below.
5.To unlock the application , open the MyLockBox app, enter the password
there, and hit Ok.
6. Now click on the “Unlock ” button to unlock your application.

17. 7. Now , youe application is able to access .
This is how you can set password to your system and application.
Result : Thus , I have successfully password protected my system and
application.

18. Practical No 4
Aim : Apply security to file folder or application using access permission and
verify.
Software Requirement: Operating system.
Procedure:
To apply security to a folder ,steps are given as follows:
1.Open the location of the folder for which security is being applied.(here we
are going to apply security to ‘Raj’ folder which is located in documents.)
2.Open the properties of the folder by simply click right on it

19. 3.Change the access permissions of the folder according to your preference.
Here I am giving full access to owner and group means they can read and write
into the folder and for others it only read only.

20. 4.Here you go! Now the permissions are successfully applied to the folder.

21. Now , no one can create any files or folders in this folder.
Result:
Thus , I have successfully applied security to file folder or application using
access permission and verified it.

22. Practical no 5
Aim : Write a program to implement Caesar Cipher
Software Requirement : Operating System , IDLE(python 3.8.5)
Program:
def encrypt(text,s):
result = ""
# transverse the plain text
for i in range(len(text)):
char = text[i]
# Encrypt uppercase characters in plain text
if (char.isupper()):
result += chr((ord(char) + s-65) % 26 + 65)
# Encrypt lowercase characters in plain text
else:
result += chr((ord(char) + s - 97) % 26 + 97)
return result
#check the above function
text = "Raj Ambere"
s = 2
print("Plain Text : " + text)
print ("Shift pattern : " + str(s))
print ("Cipher: " + encrypt(text,s))

23. Output:

24. Practical no 6
Aim : Write a program to implement Rail Fence technique.
Software Requirement : Operating System , IDLE(python 3.8.5)
Program:
s=input("Enter string: ")
k=int(input("Enter key: "))
enc=[[" " for i in range(len(s))] for j in range(k)]
flag=0
row=0
for i in range(len(s)):
enc[row][i]=s[i]
if row==0:
flag=0
elif row==k-1:
flag=1
if flag==0:
row+=1
else:
row-=1
for i in range(k):
print("".join(enc[i]))
ct=[]
for i in range(k):
for j in range(len(s)):
if enc[i][j]!=' ':
ct.append(enc[i][j])
cipher="".join(ct)
print("Cipher Text: ",cipher)

25. Output: