Diffie-Hellman Key Exchange (Value marked as red is private and only visible to its owner)Diffie-Hellman Key Exchange (Value marked as red is private and only visible to its owner)

Diffie-Hellman is a very simple algorithm which can be used to establish a shared secret between two parties.

How it works

Robot A use its private number a to generate value A and pass it to Robot B along with value g and p. Value g, p and A are all public. Robot B uses the same formula to generate value B using its private value b then transfers value B to Robot A. After all of that, Robot A and B can get same value R without exposing its private values to others.

Usage of D-H and Concept Behind

During the network communications, data can be eaily exposed to attackers. D-H provides a fantastic solution for that. Using D-H algorithm, users can estalish a secret even through public channels.

The key concept of this algorithm is Trapdoor Function which is widely used in cryptography. In this case, f(x)=g^x mod p is a Trapdoor Function, f(x) can be easily calculated when x is given but the computation of the inverse of f can hardly be done.