Util::generateUUID

static function generateUUID()
{
	if (function_exists('random_bytes'))
	{
		$data = random_bytes(16);
	}
	elseif (function_exists('openssl_random_pseudo_bytes'))
	{
		$data = openssl_random_pseudo_bytes(16);
	} else
	{
		$data = uniqid('', true);
	}

	// set version to 4
	$data[6] = chr(ord($data[6]) & 0x0f | 0x40);

	// set bits 6-7 to 10
	$data[8] = chr(ord($data[8]) & 0x3f | 0x80);

	return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($data), 4));
}