Pretty Good Privacy
My public key
pub 2048R/C9241AC7 2011-03-02 André Aparício <email@example.com> Primary key fingerprint: D844 FEEA 4792 CF05 B0A2 E587 DD69 D93B C924 1AC7
An email client like Thunderbird with the Enigmail plugin should do automatically the necessary actions in the GUI, but if needed or simply as an how-to, the following steps show how to use gpg to manually do those actions.
How to sign my key
An email client like Thunderbird with the enigmail plugin should let do this steps in the GUI, without much effort. Simpler clients like Claws Mail very signatures and encrypt emails, but don't sign keys, this step must be done manually.
$ gpg --recv-keys C9241AC7
$ gpg --ask-cert-level --sign-key C9241AC7
$ gpg --send-keys C9241AC7
How to send me encrypted stuff
$ gpg --encrypt --armor --recipient C9241AC7 plain.txt--output encrypted.gpg
How to verify my signature
If the signature is appended to the data, like in email with traditional inline PGP signing.
$ gpg stuff.txt.asc gpg: Signature made Ter 02 Abr 2013 01:10:25 WEST using RSA key ID C9241AC7 gpg: Good signature from "André Aparício <firstname.lastname@example.org>"
Or if it is detached.
$ gpg --verify signature.asc stuff.txt
How to receive encrypted stuff
Assuming I've used your PGP key and you have it configured in gpg.
$ gpg --output plain.txt --decrypt encrypted.gpg
How to sign stuff
$ gpg --clearsign www_up.txt
$ gpg --sign www_up.txt