GPGTools is now compatible with Mavericks. For those of you that don’t know what GPGTools is, it is the easiest way to setup encrypted email on your Mac. It installs two things: 1. A Mail.app plugin that allows you to toggle signing and encryption on a per-email basis with a couple of nice and easy to use buttons. 2. It installs a GPG Key manager app that helps you create an encryption key, and optionally send it to a key server for others to search.
Once you get this installed it is pretty easy to start sending secured emails. You will be prompted to enter your password to read/send encrypted emails, but that’s just about the hardest part. (The most confusing part is that you have to do a key exchange first, before you can send and receive encrypted emails. That’s why many people, including me, post their public keys on contact pages.)