Symmetric Encryption: DES and AES

This lecture covers the symmetric encryption algorithms DES and AES. DES weak keys and attacks are discussed, leading to the development of AES. The lecture explains the structure of AES, its key lengths, and the importance of the initial vector (IV) in different modes of operation like ECB, CBC, OFB, and CTR. The XTS mode for encrypting hard disks is also introduced, along with the concept of ciphertext stealing. The instructor emphasizes the importance of avoiding ECB mode, using unique IVs, and understanding the various modes of operation for secure encryption.