Topic: Cryptography and Network Security
A company wants to transmit data between its two offices with full confidentiality and integrity. Private IP addresses used by system inside the company should also be confidential. Which of the following IPSec configuration will meet the requirements?
- A. IPSec using AH in Tunnel mode
- B. IPSec using ESP in Transport mode
- C. IPSec using ESP in Tunnel mode
- D. IPSec using AH in Transport mode
Answer: C. IPSec using ESP in Tunnel mode
Explanation: To ensure confidentiality, ESP (Encapsulating Security Payload) must be used, as AH (Authentication Header) only provides integrity and authentication without encryption. To keep the internal Private IP addresses confidential, Tunnel mode must be used because it encapsulates the entire original IP packet (including its headers) inside a new IP packet. Transport mode leaves the original IP header exposed.