The gpg key at ​https://winswitch.org/gpg.asc used e.g. by the Debian / Ubuntu repos has expired:

$ curl -s  https://winswitch.org/gpg.asc  | gpg -

pub  1024D/F18AD6BB 2007-04-18 Antoine Martin <[email protected]>
uid                            [jpeg image of size 4992]
sub  2048g/6E23E963 2007-04-18 [expires: 2018-05-04]

leading to errors when one runs apt-get update:

Err:17 http://xpra.org xenial Release.gpg
  The following signatures were invalid: KEYEXPIRED 1525416977  KEYEXPIRED 1525416977  KEYEXPIRED 1525416977

Hi all, I can not install xpra on Ubuntu 17.10 Artful AArdvark because I get the following:

W: GPG error: http://winswitch.org artful Release: The following signatures were invalid: EXPKEYSIG 18ADB31CF18AD6BB Antoine Martin <[email protected]>
E: The repository 'http://winswitch.org artful Release' is not signed.

I followed instructions on: ​https://winswitch.org/downloads/debian-repository.html?dist_select=artfulbeta

and on: https://winswitch.org/trac/ticket/304

Steps to reproduce:

apt-get install curl
curl https://winswitch.org/gpg.asc | apt-key add -

and

apt-get install dirmngr
apt-key adv --fetch-keys https://xpra.org/gpg.asc

both get me the above message; while

apt-key adv --keyserver keys.gnupg.net --recv-keys F18AD6BB

results in a connection timeout.

Please advice, Thanks