public_key

        # OpenSSL::PKey::DH.public_key

(from ruby core)
### Implementation from DH
---
    dh.public_key -> dhnew

---

Returns a new DH instance that carries just the DH parameters.

Contrary to the method name, the returned DH object contains only
parameters and not the public key.

This method is provided for backwards compatibility. In most cases,
there is no need to call this method.

For the purpose of re-generating the key pair while keeping the
parameters, check OpenSSL::PKey.generate_key.

Example:
    # OpenSSL::PKey::DH.generate by default generates a random key pair
    dh1 = OpenSSL::PKey::DH.generate(2048)
    p dh1.priv_key #=> #<OpenSSL::BN 1288347...>
    dhcopy = dh1.public_key
    p dhcopy.priv_key #=> nil