Symmetric Encryption: Basics and Techniques

This lecture covers the fundamentals of symmetric encryption, including definitions, techniques like substitution ciphers, and advanced methods such as the one-time pad. It also delves into historical encryption machines like Enigma and modern standards like AES. The instructor explains the operation of DES, its critiques, and the development of AES as a successor. Additionally, the lecture explores the ChaCha20 algorithm, modes of operation in block ciphers, and the concept of asymmetric encryption. Various encryption techniques, their strengths, weaknesses, and real-world applications are discussed in detail.