Jawaharlal Nehru Technological University Hyderabad MCA Information Security Previous Question Paper (September/October - 2022 - R15)

Symmetric key cryptography, while efficient, faces several significant challenges:

• Key Distribution: Securely sharing the secret key between communicating parties without interception is difficult, especially in large networks.
• Scalability: In a network with n users, each pair requires a unique key, leading to O(n²) keys, which becomes unmanageable as the number of users grows.
• Lack of Non-repudiation: Because both sender and receiver use the same key, it is impossible to prove which party generated a specific message, making digital signatures difficult to implement.
• Key Management: Frequent key changes are necessary to maintain security, requiring complex protocols for key generation, storage, and revocation.

Security attacks are categorized based on their impact on system resources:

• Passive Attacks: The attacker monitors transmissions to obtain information without altering data. These include Release of Message Contents (e.g., reading sensitive data) and Traffic Analysis (observing patterns or frequency of messages).
• Active Attacks: The attacker attempts to alter system resources or affect their operation. These include Masquerade (pretending to be an authorized entity), Replay (capturing and retransmitting data), Modification of Messages (altering legitimate data), and Denial of Service (disrupting or preventing normal network operations).