V2e: Block ciphers: AES (Applied Cryptography 101)

Welcome to "V2e: Block Ciphers: AES," the fifth lecture in "Symmetric-Key Encryption" chapter in Alfred Menezes's "Crypto 101: Building Blocks" course, The lecture is focused on the Advanced Encryption Standard (AES), the most widely used symmetric-key encryption algorithm. This video is ideal for undergraduate and graduate students in computer science, software engineering, mathematics, applied cryptography, and cybersecurity professionals looking to deepen their understanding of block ciphers and modern encryption techniques. In this lecture, we explore AES, which utilizes substitution-permutation networks (SPNs) to provide strong encryption. You will learn how AES operates through several key steps, including the S-box substitution, the MixColumn operation, and key scheduling, ensuring both security and efficiency. We cover AES’s use of multiplication in Galois fields, which strengthens the algorithm against attacks. The video also discusses the AES structure, including its key sizes (128, 192, and 256 bits), the number of rounds (10, 12, and 14), and the factors that contribute to its high performance in both software and hardware implementations. AES is at the heart of modern cryptography, securing everything from government communications to everyday transactions. By the end of this video, you’ll have a solid understanding of how AES works, its security features, and its widespread use in protecting digital information in symmetric-key encryption systems. Lecture playlist: https://www.youtube.com/playlist?list=PLA1qgQLL41SRsHMtsb4up5fTytDeHV_yJ Course web page: https://cryptography101.ca/crypto101-building-blocks/ The slides are available on the course web page. Other cryptography courses: https://cryptography101.ca Slides 00:00 Introduction 00:37 Slide 81: The Advanced Encryption Standard (AES) 01:35 Slide 82: Substitution-permutation networks 02:57 Slide 83: Substitution-permutation networks (2) 04:57 Slide 84: AES 05:54 Slide 85: AES round operations 06:05 Slide 86: AddRoundKey 06:46 Slide 87: SubBytes 11:33 Slide 88: The finite field GF(2^8) 13:07 Slide 89: S-box definition 13:48 Slide 90: The AES S-box 14:23 Slide 91: ShiftRows 16:19 Slide 92: MixColumns 18:41 Slide 93: The mutliplication-by-c(x) operation 20:25 Slide 94: AES encryption 20:46 Slide 95: AES decryption 22:10 Slide 96: AES key schedule (for 128-bit keys) 23:25 Slide 97: AES key schedule function fi 23:25 Slide 98: Performance 24:31 Coming up