How can two computers share a piece of secret information without anyone else knowing? Diffie-Hellman key exchange is one of the core algorithms in cryptography for solving this problem. In this video, we build an intuition for how the algorithm works and why it's secure. *** Spanning Tree is an educational video series about computer science and mathematics. See more at To be notified when a new video is released, sign up for the Spanning Tree mailing list at You can support the Spanning Tree channel at Spanning Tree is created by Brian Yu. Email me at brian@ to suggest a future topic.