Install goopg by entering the following commands in the terminal:
sudo apt update sudo apt install goopg
Description:
GPG for Chromium GMail
Goopg is a Chromium Native Messaging Host utility for GMail. It allows one to verify and sign emails in GMail web page, using GnuPG. The Chrome 'goopg' Extension is also required.
Homepage: http://leoiannacone.github.io/goopg/
Version: 0.3.1-9
Section: universe/mail