Question 1
(a)
What are the key principles of security?
3 Marks
(b)
Differentiate between cryptography and steganography.
4 Marks
(c)
What is cryptanalysis? Explain 5 techniques of how attackers can launch attacks.
7 Marks
Gujarat Technological UniversitySummer 2025 Examination
GTU 3170720 Information security (IS) Summer 2025 Paper Solution & PDF
B.E. · Computer Engineering · Semester 7 · Subject Code: 3170720
Total Marks70 MarksExternal theory exam
Passing Marks23 Marks33% minimum cutoff
Exam Duration2.5 Hours2:30 PM – 5:00 PM
Paper Structure5 QuestionsWith internal OR choices
Question 2
(a)
What would be the transformation of a message ‘Happy Birthday to you’ using Rail Fence technique level =3?
3 Marks
(b)
What is the idea behind meet-in-the-middle attack?
4 Marks
(c)
Explain the steps in the various rounds of DES.
7 Marks
OR OPTION
(c)
Explain the steps in the various rounds of AES.
7 Marks
Question 3
(a)
What is an Initialization Vector(IV)? What is its significance?
3 Marks
(b)
Generate a Cipher text for plain text ‘ACT’ with key ‘GYBNQKURP’ using hill cipher.
4 Marks
(c)
Explain RSA algorithm and also compute public key and private key of RSA with p- 53, q=59 and e = 3.
7 Marks
OR OPTION
(a)
Differentiate between diffusion and confusion with example
3 Marks
(b)
Generate a Cipher text for plain text ‘MISSION’ with key ‘IMPOSSIBLE’ using playfair cipher.
4 Marks
(c)
Explain the Deffie Hellman key exchange algorithm in detail. In a Diffie Hellman Key Exchange, Alice and Bob have chosen prime value 11 and 7. If Alice’s secret key is 3 and Bob’s secret key is 6, what is the secret key they exchanged?
7 Marks
Question 4
(a)
Differentiate between Session key and Master key.
3 Marks
(b)
Why is SHA more secure than MD5?
4 Marks
(c)
Discuss X.509 Certificates.
7 Marks
OR OPTION
(a)
What are the common causes for revoking a digital certificate?
3 Marks
(b)
What is the difference between MAC and message digest?
4 Marks
(c)
Discuss Secure Hash Algorithm (SHA)
7 Marks
Question 5
(a)
Explain the following properties of hash function
i)One way property
ii)Weak
collision resistance
3 Marks
(b)
Name the four key steps in the creation of a digital certificate.
4 Marks
(c)
Discuss the working of KERBEROS authentication protocol.
7 Marks
OR OPTION
(a)
What are the three aspects of a 3-factor authentication?
3 Marks
(b)
What is KDC? With the help of diagram explain how KDC do key distribution.
4 Marks
(c)
Discuss Digital signature algorithm.
7 Marks
College Exam Groups
Studying for Information security?
Circulate this solved paper with KaTeX formulas and 1-click AI step solvers to your batchmates on WhatsApp or Telegram.
About this Examination Paper & Attribution
Official Gujarat Technological University (GTU) examination paper and step-by-step solutions for Information security (IS) (Summer 2025, B.E. · Computer Engineering, Sem 7). Features complete 70-mark regular & remedial examination pattern, official marking distribution across all 5 questions, and direct 1-click official PDF download.
Transcribed for student exam preparation from Gujarat Technological University official examination archives. Questions, syllabus guidelines, and curriculum marking schemes remain the intellectual property of Gujarat Technological University.