I have some worry about password-protected Zip files. From what I understand, even though a Zip file is password protected, you can still access it to look at the files on it and their types. This being the case, how secure is such a file, really? It's not a stretch to think that someone could intercept such a file, and completely replace the material with same named items that are virus laden and then pass it on. Am I just being paranoid or is this a real threat?