The Encapsulating Security Payload (ESP) protocol of IPSec and the privacy module in Version 3 of the Simple Network Management Protocol both require that
implementations must support Data Encryption Standard (DES) encryption in Cipher Block Chaining (CBC) mode.
(a) Briefly explain how CBC mode works with a symmetric block cipher (e.g. DES).
(b) Briefly explain why CBC is the most appropriate mode for encryption in applications such as IPsec and SNMP.
(c) Streaming video applications (e.g. YouTubeiTikTok) have become very popular. Briefly explain why CBC is not the most appropriate mode for these applications, and
briefly describe a more appropriate mode for them.
Sample Solution
