Symmetric Encryption: Basics and Techniques

This lecture covers the fundamentals of symmetric encryption, including definitions of cryptography, cryptology, and encryption. It explains the process of encryption and decryption, emphasizing the importance of keys. Advanced topics such as substitution ciphers, the one-time pad, and DES are discussed, along with their strengths and weaknesses. The lecture also delves into the intricacies of the Advanced Encryption Standard (AES) and its operation. Additionally, it explores the ChaCha20 algorithm, modes of operation in block ciphers, and the concept of asymmetric encryption. Practical examples and historical context are provided to illustrate the concepts.