function _openid_dh_xorsecret($shared, $secret) {
$dh_shared_str = _openid_dh_long_to_binary($shared);
$sha1_dh_shared = sha1($dh_shared_str, TRUE);
$xsecret = "";
for ($i = 0; $i < strlen($secret); $i++) {
$xsecret .= chr(ord($secret[$i]) ^ ord($sha1_dh_shared[$i]));
}
return $xsecret;
}