Using GnuPG (gpg) for simple file encryption

How to use GnuPG for simple cases.

1. Install gpg, e.g.,

   sudo port install gnupg

2. Create a public/private key for yourself, e.g.,

   gpg --gen-key

   (you will have to answer some questions, I used 'knoto' as my comment
3. Encrypt a file, e.g.,

   gpg -e -r knoto myfile.foo

   (creates myfile.foo.gpg that can only be decrypted by knoto).