Secret Color Exchange

Learn how to establish a shared secret in public, based on the Diffie-Hellman key exchange.

Imagine you and a friend want to create a secret code that only you two know, but you can only talk through a phone that someone else is listening to. This puzzle shows you how to solve this impossible-sounding problem using the magic of mathematics! The Diffie-Hellman key exchange, invented in 1976, is one of the most important discoveries in cryptography and is used to secure internet communications worldwide.