RTU Kota B.Tech 6th Semester Information Security Systems Question Paper 2025 (CSE/IT/AI)

RTU Information Security Systems 2025 Paper Review

Preparing for the Rajasthan Technical University B.Tech Information Security Systems exam requires a firm grasp of cryptographic algorithms, network protocols, and threat mitigation frameworks. For developers building full-stack web platforms, this theoretical foundation dictates exactly how you handle user authentication, hash passwords in a database, and secure API endpoints against unauthorized access. You cannot deploy a commercial application or manage sensitive student data without understanding how symmetric and asymmetric encryption protects information in transit.

The 2025 paper tests your capability to execute mathematical key exchanges, trace block cipher rounds, and apply digital signature algorithms. Publishing this specific 6th-semester paper review directly to exam-support.in provides engineering students exactly what they need to understand how examiners construct logical security problems and distribute marks across the cryptographic modules. This targeted preparation strategy helps approach the exam confidently, Jaiprakash.

Understanding the Exam Pattern

The RTU theory examination is a three-hour paper worth 70 marks. The paper features three distinct sections designed to evaluate both foundational security definitions and quantitative cryptographic calculations.

• Part A: This section contains ten compulsory questions worth two marks each. You must define terms like non-repudiation, state the difference between a block cipher and a stream cipher, explain the avalanche effect, or list the active and passive security attacks under 30 words.
• Part B: You will find seven questions here. You must answer five of them. Each question is worth four marks. Your answers require executing short mathematical calculations like the Euclidean algorithm for finding the greatest common divisor, explaining the operational modes of block ciphers (ECB, CBC), or detailing the steps of the Diffie-Hellman key exchange.
• Part C: This section offers five major questions. You need to answer three. Each question carries ten marks. These require you to perform complete RSA encryption and decryption for given prime numbers, draw the complete Feistel structure and key generation schedule for the Data Encryption Standard (DES), or explain the exact handshake protocol for Secure Sockets Layer (SSL/TLS).

Core Topics Evaluated in the Paper

The 2025 question paper covers several critical modules that establish the mathematical rules for digital defense. Focus your study time on these specific areas to maximize your score.

Classical Cryptography and Mathematics

This module evaluates your understanding of basic substitution and transposition ciphers. You must practice encrypting and decrypting short strings using the Caesar cipher, Vigenère cipher, and Playfair matrix. Establish a strong mathematical baseline by studying modular arithmetic, Fermat's Little Theorem, and Euler's Totient function, as these form the engine for modern algorithms.

Symmetric Key Cryptography

Symmetric encryption uses a single shared key for both locking and unlocking data. You must master the structural block diagrams of DES and the Advanced Encryption Standard (AES). Focus heavily on the exact operations within an AES round: SubBytes, ShiftRows, MixColumns, and AddRoundKey. Expect questions asking you to compare the key sizes and security margins of DES, Triple DES, and AES.

Asymmetric Cryptography and Key Management

Public-key cryptography uses a mathematical key pair. You must master the RSA algorithm step-by-step. Practice calculating the modulus $n$, the totient $\phi(n)$, and finding the public exponent $e$ and private key $d$. You must execute the encryption and decryption equations:

$$C = M^e \pmod{n}$$

$$M = C^d \pmod{n}$$

Additionally, study the Diffie-Hellman key exchange and the vulnerabilities it faces, specifically the Man-in-the-Middle attack.

Message Authentication and Hash Functions

Data integrity ensures a message has not been altered. You must understand the structural properties of cryptographic hash functions, focusing on collision resistance. Study the operation of the Secure Hash Algorithm (SHA) family and MD5. Review how Digital Signatures combine hashing with asymmetric encryption to verify both the sender's identity and the message's integrity.

Network and System Security

This module focuses on protecting network perimeters and data in motion. Study the architecture of IPsec (Transport and Tunnel modes), SSL/TLS architecture, and PGP for email security. You must also understand system-level threats including viruses, worms, and Trojans. Review firewall design principles, differentiating between packet-filtering firewalls, stateful inspection, and application-level gateways.

Answer Writing Strategy for High Marks

RTU evaluators look for clean block diagrams, explicit mathematical substitutions, and clear comparative tables. Use a blue pen for text explanations and math steps. Use a black pen and ruler for drawing encryption structures, network topology diagrams, and algorithm flowcharts.

In Part A, answer directly. If a question asks for the definition of confidentiality, state clearly that it is the principle ensuring that information is not made available or disclosed to unauthorized individuals, entities, or processes.

In Part B, use clear computation structures. When tracing the Diffie-Hellman key exchange, explicitly write out the global public elements (prime $q$ and primitive root $\alpha$), the private keys chosen by users A and B, the calculated public keys, and the final shared secret key calculation to prove your logic.

In Part C, precision in mathematical execution is critical. When solving a ten-mark RSA problem, clearly separate your steps. First, list $p$ and $q$ and calculate $n$. Second, calculate $\phi(n)$. Third, show the condition for selecting $e$. Fourth, use the Extended Euclidean algorithm to calculate $d$. Finally, show the modular exponentiation for generating the ciphertext $C$. Draw a neat box around your final encrypted value.

Time Management During the Exam

Allocate exactly 20 minutes to Part A. Spend 40 minutes addressing the five short-answer questions in Part B. Reserve the remaining 120 minutes for the three long-answer questions in Part C. Computing large modular exponentiations, drawing complete AES round functions, and detailing network security handshake protocols requires steady focus and significant writing time to prevent arithmetic mistakes. This distribution guarantees you 40 minutes per major question, giving you time to double-check your modular arithmetic calculations. Use the final 10 minutes to verify your question numbering, ensure all block diagram arrows indicate the correct data flow, and check that your encryption outputs align with the formula logic.