Directory and file-level encryption is a beautiful thing in Ubuntu. No additional applications to install. Or, at least on 9.04 (Jaunty). On 9.10 (Karmic), they removed this useful feature as a default option in the install for some reason. But, not to worry, it can be readded: In Jaunty, just right-click a file or folder in Nautilus and select encrypt. Assuming you've created a GPG encryption key for files and e-mail, it'll allow you to apply that encryption to it. In Karmic, this feature is removed. To re-add it, the open Synaptic Package Manager, find, then install the seahorse-plugin. Reboot. "encrypt" and "sign" will then be options in Nautilus. Launchpad is tracking this as the following bugs: #390744 #393645