Man-in-the-middle Attack on the Diffie-Hellman Protocol

Man-in-the-middle attack

The man-in-the-middle attack applies to any situation where an attacker (Fred, in the illustration below) can intercept and alter messages sent on the communication channel between Alice and Bob. That is arguably the most well-known attack against a cryptographic protocol and is one that the designers of any cryptographic protocol need to take measures to prevent.