looking for tool to en/decrypt files or text

[poor_mans_knoppix]

Hi out there;

I'm looking for a tool to encrypt and later decrypt files or at least the content of text - files.
I don't want to sent the files or text by EMail - it's just for some content I don't like to save unencrypted to my hard-disk like a collection of my passwords or things like that - just in case anyone gets his hands on it.
No one but me is to know the password (-> no need for public / privat key)

In the forum I only saw different posts relating encryption in E-Mail applications.
As I found in kpackage there are alredy the gnupg*-packages installed which are frequently mentioned in these posts. Is there a way / tool I can use them for my intentions?

Is there a tool to do all this included within Knoppix? GUI - Tools would be fine but commandline is fine too.
Here an Java-example what it would be what I think of:
http://cif.rochester.edu/~la002k/solitaire.htm

My system is:
Knoppix 4.0 booted "fromhd" by loadlin in a FreeDos-Installation.

I'd like to find a solution which is easy to use and has no need to add packages (as well as this is said to be possible again with unionfs and knx 4.0)

Thanks in advance for your time & answers!
Have a nice day - poor_mans_knoppix

[poor_mans_knoppix]

Just found a possible solution, which is 100% Knoppix-included in a two-year-old post.

http://www.knoppix.net/forum/viewtopic.php?t=3403&highlight=mnt+crypt

Stil works with KNX4.0 :)

Is a nice solution - stil a lot of commands to type (OK, two if once setup...)
Stil the problem with the modified /etc/fstab - as I'd like to stick as close aas possible to the Live-Version of KNX...

Any other Ideas?