1,隨機生成auth_key
function build_auth_key()
{
$chars = 'abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
// $chars .= '`~!@#$%^&*()_+-=[]{};:"|,.<>/?';
$chars = str_shuffle($chars);
return substr($chars, 0, 40);
}