"This article is a step-by-step guide to using two passwords
with EncFS. The primary password is required and may be used to
secure all data; the secondary password is optional and may be
stored on USB stick or other removable media and used to secure
more sensitive data. EncFS can also be combined with block device
encryption for maximum security. Block device encryption is
described in a previous article by Michael Petullo, Disk encryption
in Fedora: Past, present, and future..."