Q.1
14 Marks(a)
Define Cryptography, Cryptanalysis and Cryptology.
(b)
Encrypt the following text with Caesar cipher: (Key=3) “Cryptography and Network Security”.
Gujarat Technological UniversitySummer 2026 examination
GTU 3161606 Cryptography and Network security Summer 2026 Question Paper & PDF
B.E. · IT Engineering · Semester 6 · Subject code 3161606
- Total
- 70 marks
- To pass
- 23 marks (33%)
- Duration
- 2.5 Hours 10:30 AM – 1:00 PM
- Questions
- 5 with internal choice
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11 of 25 questions on this paper were also asked in other years. 4 more are types of question GTU sets again with new data. Each is marked below with the years it appeared.See all 17 repeated 3161606 questions, most asked first
Q.2
14 Marks(b)
Construct a playfair matrix with the key “moonmission” and encrypt the message “greet”.
Also asked in Winter 2025 Q2c, Summer 2025 Q2a
OR
Q.3
14 Marks(a)
Find 3³¹ mod 7 using Fermat’s little theorem.
(b)
Find GCD(2740, 1760) using Euclidean algorithm. Show each intermediate result.
Also asked in Winter 2025 Q4b, Summer 2025 Q4b OR
OR
(a)
With the help of Euler Totient function find ø(15).
(c)
List types of digital signature and discuss in detail Elgamal digital signature scheme.
Also asked in Winter 2025 Q5c, Summer 2025 Q5b OR
Q.4
14 Marks(a)
What is the difference between HTTP and HTTPS?
(b)
In a public key system using RSA, the ciphertext intercepted is C=10 which is sent to the user whose public key is e=5, n=35. What is the plaintext M?
Also asked in Summer 2025 Q4b
(c)
Demonstrate the working of SSL Record Protocol with the help of necessary diagrams.
Also asked in Winter 2025 Q5b OR, Summer 2025 Q5b
OR
(b)
Find out inverse of 550 with extended Euclidean algorithm in Galois Field 1759.
Also asked in Winter 2025 Q4b OR
(c)
Explain Diffie Hellman scheme with diagram. For Diffie- Hellman algorithm, two publically known numbers are prime number 23 and primitive root of it is 9. A selects the random integer 4 and B selects 3. Compute the public key of A and B. Also compute common secret key.
Also asked in Winter 2025 Q4c OR, Summer 2025 Q4c
Q.5
14 Marks(a)
Discuss MAC based on Block Ciphers.
(b)
Discuss various ways of Distribution of Public Keys.
(c)
Demonstrate the working of Kerberos Version 4 Authentication Dialogue with detailed steps.
Also asked in Winter 2025 Q5a OR, Summer 2025 Q5c OR
OR
(a)
Illustrate Man-in-Middle attack.
(b)
Discuss MAC based on Hash Functions (HMAC).
(c)
Consider a scenario where Prachi wants to send a secret message M and her signature to Prayag. Prachi takes help of Prayag to validate her digital signature, but does not want to reveal M to Prayag. Prayag performs the necessary steps to send Prachi ‘s messages to Pramod. Draw and explain this scenario using symmetric key cryptography.
More Cryptography and Network security papers
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About this paper
Official Gujarat Technological University (GTU) examination paper for Cryptography and Network security (Summer 2026, B.E. · IT Engineering, Sem 6). 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.