Extending the expiry on a GPG key is not very hard, but it's easy to forget a step. Here's how I did my last expiry bump.
Update the expiry on the main key and the subkey:
gpg --edit-key KEYID
> expire
> key 1
> expire
> save
Upload the updated key to the keyservers:
gpg --export KEYID | curl -T - https://keys.openpgp.org
gpg --keyserver keyring.debian.org --send-keys KEYID
and then removing the old one from your GitHub profile and pasting in the output of:
gpg --armor --export KEYID | xsel -b
If you use Enigmail in Thunderbird, you'll need to also export the new public key:
gpg --export KEYID > newkey.gpg
and import that newkey.gpg file into its keyring:
- Tools | OpenPGP Key Manager
- File | Import Public Key(s) From File