Create Subkeys

… on your local laptop.

Note

Reminder from gpg2 --list-secret-keys:

sec   rsa4096/0xCCCCCCCCCCCCCCCC 2015-02-01 [SCA] [expires: 2020-01-31]
# ...

gpg2 --expert --edit-key CCCCCCCCCCCCCCCC

gpgp> addkey
# select 8 add a new RSA sub-key to your key
# select A, then S, then E to get a pure authentication key. Then Q to continue.
# select same expiry as for the rest of the key and then answer y to save changes.

gpg> quit