The diffie hellman key exchange uses prime numbers to generate an asymmetric key pair which is used to create a secure channel over which a privet symmetric key can be sent.

Diffie-Hellman is not as much a cipher as a means of securing exchanging keys. You would use it to securely notify someone else of a symmetric shared key that you both would use for encrypting data.

Think of it as more a key exchange method utilizing public and private keys than an actual cipher methodology.

Winfield Diffie is an American cryptographer and computer security expert. He is best known for his pioneering work in public-key cryptography, along with Martin Hellman, which laid the foundation for secure communication over the internet. Diffie and Hellman's invention of public-key cryptography revolutionized modern cryptography and made secure online communication possible.

Diffie-Hellman Elliptical Curve Cryptography

The most common hybrid system is based on the Diffie-Hellman key exchange, which is a method for exchanging private keys using public key encryption. Diffie-Hellman key exchange uses asymmetric encryption to exchange session keys. These are limited-use symmetric keys for temporary communications; they allow two entities to conduct quick, efficient, secure communications based on symmetric encryption, which is more efficient than asymmetric encryption for sending messages. Diffie_Hellman provides the foundation for subsequent developments in public key encryption. It protects data from exposure to third parties, which is sometimes a problem when keys are exchanged out-of-land.