function guidv4()
{
if (function_exists('com_create_guid') === true)
return trim(com_create_guid(), '{}');
$data = openssl_random_pseudo_bytes(16);
$data[6] = chr(ord($data[6]) & 0x0f | 0x40); // set version to 0100
$data[8] = chr(ord($data[8]) & 0x3f | 0x80); // set bits 6-7 to 10
return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($data), 4));
}
function create_guid() { // Create GUID (Globally Unique Identifier)
$guid = '';
$namespace = rand(11111, 99999);
$uid = uniqid('', true);
$data = $namespace;
$data .= $_SERVER['REQUEST_TIME'];
$data .= $_SERVER['HTTP_USER_AGENT'];
$data .= $_SERVER['REMOTE_ADDR'];
$data .= $_SERVER['REMOTE_PORT'];
$hash = strtoupper(hash('ripemd128', $uid . $guid . md5($data)));
$guid = substr($hash, 0, 8) . '-' .
substr($hash, 8, 4) . '-' .
substr($hash, 12, 4) . '-' .
substr($hash, 16, 4) . '-' .
substr($hash, 20, 12);
return $guid;
}