Diffie-Hellman Key Exchange Default Value.
This is used to establish an association between the Relying Party and the OpenID Provider.
See RFC 2631: http://www.ietf.org/rfc/rfc2631.txt
define('OPENID_DH_DEFAULT_MOD', '155172898181473697471232257763715539915724801' . '966915404479707795314057629378541917580651227423698188993727816152646631' . '438561595825688188889951272158842675419950341258706556549803580104870537' . '681476726513255747040765857479291291572334510643245094715007229621094194' . '349783925984760375594985848253359305585439638443');