And there ist an article here:
This is a very nice idea:) However, I think the file still can be copied during the time when application is opened? Anyway, well deserved +1 :)
Well, not so easy, because the file is only in the cache. Maybe it ist possible, but not without mayor difficulties. 100% security is not possible, every file and data in your computers memory can be copied...
You can try with a file with attributes FILE_ATTRIBUTE_TEMPORARY and FILE_FLAG_DELETE_ON_CLOSE. Such a file is (if enough cache memory is available) not written on harddisk and deleted when your application is closed.