In 1997, a contest began to develop a new encryption algorithm to become the Advanced Encryption Standard. After years of debate, one algorithm was chosen as the AES. But how does AES work? And what makes for a secure encryption algorithm? *** Spanning Tree is an educational video series about computer science and mathematics. See more at https://spanningtree.me/ To be notified when a new video is released, sign up for the Spanning Tree mailing list at https://spanningtree.substack.com/ Spanning Tree is created by Brian Yu. https://brianyu.me/ Email me at brian@spanningtree.me to suggest a future topic. *** 0:00 The Contest 1:02 Encryption 3:57 Confusion and Diffusion 5:44 Block Cipher 6:55 KeyExpansion 7:34 AddRoundKey 8:14 Substitution Cipher 8:55 SubBytes 11:30 MixColumns 12:53 ShiftRows 13:21 The Algorithm