/**
* Validates the openid.response_nonce parameter.
*
* @return void
* @throws OpenID_Assertion_Exception on invalid or existing nonce
*/
protected function validateNonce()
{
$opURL = $this->message->get('openid.op_endpoint');
$responseNonce = $this->message->get('openid.response_nonce');
$nonce = new OpenID_Nonce($opURL, $this->clockSkew);
if (!$nonce->verifyResponseNonce($responseNonce)) {
throw new OpenID_Assertion_Exception('Invalid or already existing response_nonce');
}
}
