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 [email protected] 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

Aug 22, 2023