In our last post, we encrypted a text document. Here’s that article in case you missed it: Using Notepad ++ to Encrypt a Text File  This post is a continuation of that theme, keeping your cloud files safe from prying eyes. Whose prying eyes? The employees and management of the various cloud companies, that’s who. Now that Microsoft has banned photos containing nudity in their SkyDrive folders, you can be certain that employees/managers/bots scan your files for offending data. Hell, your government is probably scanning those folders as well.

TrueCrypt is free. You can get it here: TrueCrypt  . Once you download TrueCrypt, install it. While it is a very powerful program, Truecrypt is mostly based on passwords. If you lose your various TrueCrypt passwords, you’re totally out of luck so anything you do with this program must be done using a password that you won’t ever forget. You’ve been warned.

The concept of this whole thing is to make an encrypted folder on your computer which will become your Dropbox folder. Since that folder is synced with your online Dropbox folder, it is automatically encrypted.  TIME OUT! In the middle of writing this post we discovered that the guide we were using simply doesn’t work. We managed to encrypt the Dropbox folder on one of our computers but not the online Dropbox folder. We’re back to square one here but we’ll update this post a.s.a.p. Yes, this is a short post but it’s been three days since our last one and we didn’t want anyone to think we’re sleeping on the job. We’re not. Things get in the way every now and then!

We’re back! 

OK, we figured it out. Although the system we started to describe is in different places all over the Internet, it does not work. What follows is the only way to secure your Dropbox contents from prying eyes. You can use the same technique on other cloud services, SkyDrive for instance, and rest assured that no one but you can access your material there…provided you remember the password.

Before we get into the how-to section of this post, we want to explain some principles about what we’re going to do here. You have to know how Dropbox works before you can understand this whole thing.

The Basics

1. There are as many Dropbox folders as there are computers that access the same account…plus one. There is one folder on the Dropbox site itself plus the same folder, more or less, on every computer that you use for the same Dropbox account.

2. If you put a file, let’s say a photo or a video, into your Dropbox folder on one computer, that computer uploads the file to your online Dropbox folder.

3. When you turn on another computer that has access to the same Dropbox account, the file that was just uploaded to the online Dropbox folder is downloaded to the current computer’s Dropbox folder. If you change a fileThis is what syncing is all about, right?

The Problem: 

1. When you change a file, Windows notes the change by telling us that the file was modified at such and such a time/date. If you modify a file, Dropbox notices this and updates that file all by itself. The next time you start your other computer(s), Dropbox sees that the version of a file isn’t the same as the one that it has in its online folder. As soon as it sees the discrepancy, Dropbox downloads the newer version of the file to whatever computer you are currently using.

2. When you are using Truecrypt, any folder you open is hidden, more or less, from Windows. In effect, that file is open only in Truecrypt, as if it was another operating system. You open Truecrypt then open the encrypted folder, add or subtract data from it and then close it before you close Truecrypt. When Truecrypt closes the folder (called dismounting), it does not update Windows on what changes have been made. As far as Windows knows, nothing has changed.

3. Do you see the problem? If Windows doesn’t tell Dropbox that the folder has changed, Dropbox doesn’t know to sync that file with either its own online version of that folder or the other versions of the same folder on any other computer that you use. Ah, there’s the rub.

The Solution: 

1. There’s only one step to this solution. Instead of letting Dropbox sync your encrypted folder by itself, you have to send the folder to Dropbox each time you add or subtract anything from it. Basically, you copy and paste the changed folder into your current computer’s Dropbox folder. Only then will Dropbox feed the newly changed folder up to your online folder. In theory, this is how it should work. While you’re mulling all of this over, we’re trying to check that this is exactly what happens. Next post, we’ll let you know if our theory worked. Wish us luck!

Thanks for reading!