A cornerstone of modern secure communications is the Diffie-Hellman key exchange. It solves the problem of two communicators who may not know each other and haven’t previously agreed on a key to negotiate a secret key in public. This may seem impossible1 but there is, in fact, a simple solution. The solution is simple enough that anyone with, say, a high school mathematics background can understand it easily. Here’s my attempt at an explanation.
Yesterday, though, I saw a video that explains the method in such a simple and clear manner that even a grade school kid still struggling with arithmetic can understand it. The video uses the metaphor of mixing paints to explain the idea of the algorithm. After that it also goes through the mathematical explanation but that seems easier and more natural after the paint explanation.
Most Irreal readers, I’m sure, already understand Diffie-Hellman or would have no trouble understanding it once they saw an explanation. Even so, the video is very much worth watching. By stripping away the mathematics it makes the idea behind the algorithm come alive.
Footnotes:
Indeed, Ralph Merkle, who independently discovered the method, was trying to prove that it was impossible when he discovered it.