The Diffie-Hellman algorithm

To understand the Diffie-Hellman (D-H) algorithm, we can rely on the so-called thought experiments or mental representation of a theory often used by Einstein.

A thought experiment is a hypothetical scenario where you mentally transport yourself to a more real situation than in the purely theoretical way of facing an issue. For example, Einstein used a very popular thought experiment to explain the theory of relativity. He used the metaphor of a moving train observed by onlookers from different positions, inside and outside of the train.

I will often apply these mental figurative representations in this book.

Let us imagine that we have our two actors, Alice and Bob, who want to exchange a message (on paper) but the main post office in the city examines the contents of all letters. So, Alice and Bob struggle a lot with different methods to send a letter secretly while avoiding any intrusion: for example, putting a key inside a metallic cage...