Today I realized that my GPG key (which I don't really use for anything except
signing git commits) was out of date. These are the steps I took to update the
expiration date:

# Update the actual key

In a terminal, run `gpg --list-secret-keys` to get the short-form ID of the key
and verify that it is indeed out of date.

The run

  gpg --edit-key 56584D0971AFE45FCC296BD74CE62A90EFC0B9B2

to enter an interactive gpg environment that lets you update the expiration. Use
the `expire` command to set the new expiration (I chose to extend it for one
year). GPG may warn you that:

  gpg: WARNING: Your encryption subkey expires soon.
  gpg: You may want to change its expiration date too.

In that case, use `key 1` to choose the subkey and `expire` to update it.

Finally, type `save` to save the updated key and exit.

Now, to get the new PGP public key block, use

  gpg --armor --export 56584D0971AFE45FCC296BD74CE62A90EFC0B9B2


# Update the key on Github

This is where I use my key the most. To update it, go to:

  https://github.com/settings/keys

Here, delete the old key (don't worry, your old commits wont be invalid) and
upload your new key.

# Update the key on sourcehut:

Update it here:

  https://meta.sr.ht/keys

# Update the key on munksgaard.me

Update the file here:

  https://github.com/Munksgaard/munksgaard.me/blob/master/publickey.txt

And publish the website again using `C-c C-e P p`.

# Update the key on gopher

Update the file here

  https://git.sr.ht/~munksgaard/munksgaard.me-gopher/tree/master/item/src/pubkey.asc

And publish the update using philnix.

# Importing Github keys

Oh, and because verifying signed commits on GitHub and other places is pretty
much the only thing I'm using GPG for (I'd love to receive an encrypted
e-mail some day!), here's how to import another users GPG-key from GitHub:

  curl https://github.com/USERNAME.gpg | gpg --import