File encryption with GnuPG

Encrypt file:

gpg -c private.txt

You will be prompted to enter a passphrase twice. The output is a file of the same name with ".gpg" as the extension.

Decrypt via:

gpg private.txt.gpg

By default the encrypted file is binary format with smaller file size. If you need ascii, then use the "-a" option which then outputs as "private.txt.asc".