Can I use my own YubiKey?

The unhelpful short answer is "sort of".

Because at Code Enigma we run our own key store servers, we usually need to have the YubiKeys physically in our hands in order to configure them. If you're comfortable with GPG encryption and using the YubiKey Personalization Tool yourself, then we can send you the private key we generate securely and you can configure your own YubiKey, but otherwise you'd need to post your YubiKey to us for configuration, at which point it's probably easier to just order a Code Enigma YubiKey, which is what we generally recommend.