Thanks for all your info! Finally I found out how to do what I wanted. It's incredible how easy it is to store tons of perfectly hidden data in Windows, and so easy. I even found how to write hidden information in the NTFS partition using just notepad!!... and I don't mean by setting the visible attribute of the files. Data can be stored in hidden streams that could be examined only by a few special functions, which only work on administrator accounts, and anyway those could be overrided by any virus using rootkit techniques. Windows is really unsecure. If a well-done rootkit virus takes the system the antivirus can't be trust. The disk must be scanned from outside, in a trusted system. In the future I will try to remove my hard disks and scan them in an isolated computer. :!: