To encrypt from the command-line do the following (example file is abc.csv). You'll be prompted for a pass phrase. It will create a new file with .gpg appended.
Code:
$ gpg -c --no-symkey-cache abc.csv
Note that the original file is still present after gpg creates the new encrypted file. You'll need to delete that.
The --no-symkey-cache option is used so that gpg doesn't cache your pass phrase. If you don't do this, you can just decrypt the file without using a pass-phrase. Seems strange to me, but that is how it works.
To decrypt (you'll be prompted for a pass phrase)
Code:
$ gpg -d abc.csv.gpg
or if wanting to go to a new file
$ gpg -d -o zztop.csv abc.csv.gpg
Not familiar with a GUI version. Probably a bunch out there though!
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