Are you: Initiating key exchange Public value
Private (secret) value
Responding to key exchange request
Receiving response to key exchange request
Base: (p) (primitive root mod m) Modulus: (m) Key bit size:
Enter a passphrase for key generation: (*)

This passphrase must remain secret!!
You must remember it until you have a shared key,
but do not provide it to anyone else, including the party with whom you wish to have a shared key.

It's easy to get the key exponent from a passphrase (Modular exponentiation).
It's hard to get the passphrase back from the key exponent (Discrete logarithm)

Sender key exponent: A = pa mod m
Responder key exponent: B = pb mod m
Shared secret key: K = pab = Ab mod m = Ba mod m