Install seahorse-sharing by entering the following commands in the terminal:
sudo apt update sudo apt install seahorse-sharing
Description:
Daemon for sharing your GnuPG keys
A daemon for sharing your GnuPG keys using HKP key sharing discovered with DNS-SD.
Homepage: http://live.gnome.org/Seahorse
Version: 3.8.0-0ubuntu2
Section: universe/gnome