(PHP 5 >= 5.3.11)
openssl_dh_compute_key — Computes shared secret for public value of remote DH key and local DH key
$pub_key
   , resource $dh_key
   )This function is currently not documented; only its argument list is available.
pub_keyPublic key
dh_keyDH key
   Returns computed key on success or FALSE on failure.