Basically, one way in which you can use truecrypt is to create a file which, when mounted, acts like a device/filesystem. This container is encrypted and the strength of encryption depends on your key or password.
As a solution it also suffers from slow initial syncing.
Setting it up is a piece of cake:
1. Install truecrypt.
Get the correct version e.g. "Standard x64" from http://www.truecrypt.org/downloads.
Install by extracting the file and executing it:
chmod +x truecrypt-7.1a-setup-x64
2. Start truecrypt and click on Create Volume
|Select encrypted file container. The other option is more useful if you have access to the hardware.|
|Using a Hidden truecrypt volume means you pay a space penalty, depending on how you distribute the space between the two volumes.|
|Select location and filename|
|Pick an algorithm. I don't know much about this, but using a cascade sounds reasonable. I guess there are performance penalties though.|
|Be aware that the container file will take up all this space -- whether it's empty or not.|
|Click on Select File, then mount. You typically need to supply both the container password and your admin password.|
|This is what the inside of the container file looks like.|
|And this is what the dropbox folder looks like|