I have an external harddisk and an usb stick. I use them sometimes with pc and sometimes with laptop. Operation systems are not same always, also sometimes windows xp, sometimes vista or linux ubuntu etc. I dont have admin-root like access to install new software there always. I want nobody else get access to my external-disk and usb drive. I know it is possible with TrueCrypt but I cant install truecrypt everywhere and I dont want either. And I am not sure if truecrypt works with all operation-systems and file-systems like fat32, ntfs, rsfs, ext3 etc... Any suggestions?