Jawaharlal Nehru Technological University Hyderabad B.Tech IV INFORMATION SECURITY Previous Question Paper (March - 2021 - R15)

Security is essential in information systems to protect data integrity, confidentiality, and availability against unauthorized access, modification, or destruction. As digital connectivity increases, the risk of cyber threats grows, necessitating robust mechanisms to ensure that sensitive information remains private and systems function reliably.

Security attacks are generally categorized into two types:

• Passive Attacks: These involve monitoring or eavesdropping on transmissions to obtain information without altering the system resources. Examples include traffic analysis and release of message contents.
• Active Attacks: These involve unauthorized modification of the data stream or the creation of a false stream. Examples include masquerade, replay, modification of messages, and denial of service.

Cryptography is divided into two primary categories based on the keys used for encryption and decryption:

Symmetric Key Cryptography: Also known as private-key or secret-key cryptography, this method uses a single shared key for both encryption and decryption. Both the sender and receiver must possess the same secret key. It is computationally efficient and suitable for bulk data encryption. Common algorithms include AES and DES. The primary challenge is secure key distribution.

Asymmetric Key Cryptography: Also known as public-key cryptography, this method uses a pair of keys: a public key for encryption and a private key for decryption. The public key is shared openly, while the private key is kept confidential by the owner. This approach solves the key distribution problem and supports digital signatures and authentication. Common algorithms include RSA and Elliptic Curve Cryptography (ECC). It is generally slower than symmetric cryptography due to complex mathematical operations.