I have entered this request into the "Terminal" program, per this documentation
gpg --keyserver hkp://keyserver.ubuntu.com --recv-keys "8439 38DF 228D 22F7 B374 2BC0 D94A A3F0 EFE2 1092" "C598 6B4F 1257 FFA8 6632 CBA7 4618 1433 FBB7 5451"
and received the expected responses:
gpg: directory /home/ubuntu/.gnupg' created
gpg: new configuration file `/home/ubuntu/.gnupg/gpg.conf' created
gpg: WARNING: options in `/home/ubuntu/.gnupg/gpg.conf' are not yet active during this run
gpg: keyring `/home/ubuntu/.gnupg/secring.gpg' created
gpg: keyring `/home/ubuntu/.gnupg/pubring.gpg' created
but the response to
gpg: requesting key EFE21092 from hkp server keyserver.ubuntu.com
was:
gpg: "8439 38DF 228D 22F7 B374 2BC0 D94A A3F0 EFE2 1092" not a key ID: skipping
gpg: "C598 6B4F 1257 FFA8 6632 CBA7 4618 1433 FBB7 5451" not a key ID: skipping
The "trustdb" was not created, the "Ubuntu CD Image Automatic Signing Key (2012) " was not imported, the "Ubuntu CD Image Automatic Signing Key " was not imported.