Encrypt and digitally sign your mails with GPG, Thunderbird and Enigmail on Ubuntu 8.04. If you don’t know, what GPG is, read the introduction from the GPG mini Howto, it won’t take long.
Install Thunderbird and Enigmail, start Thunderbird and create or add an email address. For the following operations, navigate to: OpenPGP -> Key Management
Generate a keypair with: Generate -> New Key Pair
Choose your email address and type in a strong password, set other options if wished and click on ‘Generate Key’ when you’re finished.
Create the revocation certificate and store it on a save medium away from the digital world. You can use this certificate to revoke your GPG Key, if it gets compromised.
These are the minimal preparations for GPG.
Now, you need the public key of the person...