Cryptography & Network Security Unit 1 – Security Foundations, Classical Encryption and Modern Block Ciphers: AKTU previous year questions
12 AKTU questions from Unit 1 (Security Foundations, Classical Encryption and Modern Block Ciphers) asked in 2025–2026, tagged by marks, year and topic. In short: about 29 marks of every paper come from this unit; the most asked topic is Classical Encryption Techniques (10 times); 1 questions came back in a later year. The latest ones are listed below; on the page you can filter them by 2-mark or long questions, topic and repeats.
Unit 1 previous year questions
- 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)
- Compare and contrast Output Feedback (OFB) and Counter mode of Block cipher. (7 marks, 2026, Block Cipher Modes of Operation)
- Describe the Feistel structure and explain the working of DES. (7 marks, 2026, Data Encryption Standard (DES))
- List and explain security mechanisms. (7 marks, 2026, Security Mechanisms)
- Discuss block cipher modes of operation and explain Triple DES. (7 marks, 2026, Block Cipher Modes of Operation)
- Outline the key principles of security. (2 marks, 2025, Security Services)
- Distinguish between active and passive attacks. (2 marks, 2025, Security Attacks)
- Illustrate Substitution techniques and Transposition techniques under classical encryption. (10 marks, 2025, Classical Encryption Techniques)
Most asked Unit 1 topics
- Classical Encryption Techniques – asked 10 times
- Data Encryption Standard (DES) – asked 8 times
- Block Cipher Modes of Operation – asked 6 times
Unit 1 question pattern
- 2-mark questions: 5 asked in 2025–2026
- 7-mark questions: 6 asked in 2025–2026
- 10-mark questions: 1 asked in 2025–2026
- About 29 marks from Unit 1 in every paper
- 1 questions were asked again in a later year
Unit 1 questions year by year
- 2026: 9 Unit 1 questions asked (48 marks across that year's papers)
- 2025: 3 Unit 1 questions asked (14 marks across that year's papers)