pinentry-gtk2 binary package in Ubuntu Bionic amd64

 This package contains a program that allows for secure entry of PINs or
 pass phrases. That means it tries to take care that the entered
 information is not swapped to disk or temporarily stored anywhere.
 This functionality is particularly useful for entering pass phrases
 when using encryption software such as GnuPG or e-mail clients using
 the same. It uses an open protocol and is therefore not tied to
 particular software.
 .
 The program contained in this package implements a PIN entry dialog
 using the GTK+ tool kit version 2. If the X Window System is not
 active then an alternative text-mode dialog will be used. There are
 sibling packages that implement PIN entry dialogs using other tool
 kits.

Source package