Ephemeral Diffie-Hellman

cryptography

Definition

Ephemeral Diffie-Hellman

Ephemeral Diffie-Hellman (DHE or EDH) is a variant of the Diffie-Hellman key exchange in which each party generates a fresh, temporary private key for every session rather than reusing a long-term static key.

Let be a cyclic group of prime order with generator . For each session:

1. Alice chooses uniformly at random, computes , and sends to Bob.
2. Bob chooses uniformly at random, computes , and sends to Alice.
3. Both derive the shared secret via

The private exponents and are discarded after the session ends.