JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD MCA II INFORMATION SECURITY Previous Question Paper (March/April - 2022 - R15)

A Network Security Model is designed to protect information as it is transmitted across a network. The fundamental operation involves transforming a message into a secure form using a secret key, transmitting it, and then recovering the original message at the destination.

The primary components of the model include:

• Message Source: The entity originating the information.
• Sender: The device or process that performs the security transformation (encryption).
• Communication Channel: The physical or logical medium through which data travels, which is assumed to be insecure.
• Receiver: The device or process that reverses the transformation (decryption).
• Message Destination: The final recipient of the information.
• Trusted Third Party: An entity (such as a Certificate Authority) that assists in key distribution or security management.

The requirements for a secure network model are:

• Confidentiality: Ensuring that only authorized parties can access the data.
• Integrity: Ensuring the data is not altered during transit.
• Authentication: Verifying the identities of the communicating parties.
• Non-repudiation: Preventing a sender from denying they sent a message.

The distinction between active and passive attacks lies in whether the attacker modifies the data or merely observes it.

Passive Attacks: The attacker monitors the communication channel to capture data (e.g., traffic analysis or packet sniffing). The system remains functional, and the sender/receiver are unaware of the breach.

Active Attacks: The attacker attempts to alter the system or the data stream. Examples include masquerading (pretending to be an authorized user), replay attacks (re-sending captured data), and denial-of-service (disrupting network availability).