Consider a network scenario where two users (User-1 and User-2) want to devise a common secret key so that the exchange of important information among them can be made secure by the use of some symmetric encryption technique. In order to encounter the challenge of exchanging the common secret key among them in insecure channel but in secured manners, both the users have agreed upon the use of the Diffie-Hellman Algorithm and to perform the following:

• Both the users will first create and exchange their public keys among them.
• Both will consider Prime Number q as 43 and Primitive Root α as 5 to create their public keys

Considering the above given information and assuming the Private Keys of User-1 and User-2 as 10 and 23 respectively, you are required to find the following:

1. Public Keys of Both the Users
2.  Common Secret Key 

Note: You need to apply the Algorithm for finding the Public Keys and Common Secret Key at both sides i.e., User-1 and User-2. Also, mention all necessary equations/formulas and calculation steps to give your answer.

Question No.2

Suppose a sender A wants to send a message “3” to a Receiver B by encrypting the message using RSA (Rivest–Shamir–Adleman) Algorithm. Assuming the Public Key PU of the sender A as {5,14} and Private Key PK of the receiver B as {11, 14}, you are required to perform encryption at the sender side to convert the given plain text into cipher text and perform decryption at the receiver side to convert the cipher text back into the plain text.

Note: You need to give your answer in the following table by writing all necessary calculation steps:

Encryption = Enc process goes here

Decryption = Dec process goes here

Assignment No. 01
Semester: Spring 2020
Network Security-CS315 Total Marks: 20

Due Date: 29-May, 2020

Instructions:
Please read the following instructions carefully before submitting assignment:
You need to use MS word document to prepare and submit the assignment on VU-LMS.
It should be clear that your assignment will not get any credit if:

 The assignment is submitted after due date.
 The assignment is not in the required format (doc or docx).
 The submitted assignment does not open or file is corrupt.
 Assignment is copied (partial or full) from any source (websites, forums, students, etc).

Objectives:

To enhance the learning capabilities of students about Network Security Requirements and Algorithms.

Assignment

Question 1: Marks 14

Carefully analyze the scenarios/problems mentioned below and suggest the most suitable security requirements that should be fulfilled by the organizations to overcome their respective problem(s).

1. ABC Bank is providing credit card services to its clients. One of its clients Mr. Amir lost his credit card and he received an email of credit card transaction from the bank.

2. XYZ Soft wants to check that which employee has accessed their system after office working hours but it is unable to trace the employee because organization don’t keep any system logs.

3. ITC University is providing access to its students of their results through online portal but one of its students is executing scripts to access the server again and again that causes the server to get down.

4. A student takes admission in the university. After a year, university found that student’s actual information is not matching with the information entered in the university’s database.

5. A doctor in a hospital detected that one of its patient’s information has been altered by one of the medical staff who was not authorized to access that information.

6. Glass Soft is providing online gaming facility to end users but one of its employees leaked the information and now users getting spam messages.

7. Chatbot organization is providing online chatting services to its users. It’s two users A and B are chatting with each other while some user C is sending message to A while pretending that it’s B.

Question 2: Marks 06

Given tables contain the combinations of Plain text, Cipher text and Key Stream. You are required to discover Cipher text and Key stream in binary form while Plain text in decimal form with the help of stream cipher algorithm using following data:

a) Given plain text and key stream. Discover Cipher Text (binary).

b) Given cipher text and key stream. Discover Plain Text (decimal).

c) Given plain text and cipher text. Discover Key Stream(binary).