Cryptography & Network Security (CNS) AKTU previous year questions 2018–2026
Every Cryptography & Network Security question from 10 AKTU papers, tagged by unit, topic and marks. A few recent questions from each unit are listed below; open the page to filter by unit, topic or mark type.
Unit 1: Security Foundations, Classical Encryption and Modern Block Ciphers – AKTU PYQs
- Compare steganography and Cryptography. (2 marks, 2026, Steganography)
- Define cryptography and state any two security services. (2 marks, 2026, Security Services)
- What is the difference between stream cipher and block cipher? (2 marks, 2026, Stream and Block Ciphers)
- Discuss Shannon’s theory of confusion and diffusion. Explain. (7 marks, 2026, Shannon Confusion and Diffusion)
- Explain substitution and transposition ciphers with suitable examples. (7 marks, 2026, Classical Encryption Techniques)
Unit 2: Mathematical Foundations, AES and Public Key Cryptography – AKTU PYQs
- State Chinese remainder theorem. (2 marks, 2026, Chinese Remainder Theorem)
- State Fermat’s Little Theorem. (2 marks, 2026, Fermat Theorem)
- Calculate Φ(35). (2 marks, 2026, Euler Theorem)
- Write algorithm for primality test. How it works. (7 marks, 2026, Primality Testing)
- Explain modular arithmetic and Extended Euclidean Algorithm with example. (7 marks, 2026, Extended Euclidean Algorithm)
Unit 3: Message Authentication, Hash Functions and Digital Signatures – AKTU PYQs
- Explain requirement of Hashing. (2 marks, 2026, Hash Functions)
- What is the purpose of a digital signature? (2 marks, 2026, Digital Signatures)
- State and proof digital signature standard (DSS). (7 marks, 2026, Proof of Digital Signature Algorithm)
- Explain authentication requirements and hash functions. Discuss birthday attack. (7 marks, 2026, Hash Functions)
- Explain Hash Function? Discuss SHA- 512 with all required steps, round function & block diagram. (7 marks, 2026, Secure Hash Algorithm (SHA))
Unit 4: Key Distribution, Authentication Applications and Email Security – AKTU PYQs
- What is Diffie–Hellman key exchange used for? (2 marks, 2026, Diffie-Hellman Key Exchange)
- Write role of TGS. (2 marks, 2026, Kerberos)
- Define Public Key Infrastructure (PKI (2 marks, 2026, Public Key Infrastructure)
- Compare Kerberos 4 and Kerberos 5. (7 marks, 2026, Kerberos)
- Explain symmetric key distribution methods and Diffie–Hellman key exchange. (7 marks, 2026, Symmetric Key Distribution)
Unit 5: IP Security, Secure Transactions and System Security – AKTU PYQs
- List the function of dual signature. (2 marks, 2026, Secure Electronic Transaction (SET))
- Write requirement of padding in ESP. (2 marks, 2026, IP Security)
- Mention any two functions of a firewall. (2 marks, 2026, Firewalls)
- Explain IP security. Explain its architecture. (7 marks, 2026, IP Security)
- Explain IP Security architecture and its components. (7 marks, 2026, IP Security)