Seems to me that the Diffie-Hellman key agreement protocol results in a symmetric shared private key. However, the books I've used for Security+ prep put it with RSA as a public-key algorithm.

In the realm of secure communications, data exchange and secret key agreement algorithms are pivotal for establishing confidentiality and ensuring the integrity of information transmitted over ...

In the 1970s, Whitfield Diffie co-wrote the recipe for one of today’s most widely used security algorithms in a paper called “New Directions in Cryptography.” The paper was a blueprint of what came to ...

Twenty years before the Internet would create a need for it, a public-key cryptographic standard was discovered and patented by Whitfield Diffie, along with another student and a professor at Stanford ...