pinentry-curses binary package in Ubuntu Xenial 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 curses tool kit, meaning that it is useful for users
 working in text mode without the X Window System. There are sibling
 packages that implement PIN entry dialogs that use an X tool kit. If
 you install any of the graphical packages then this package is not
 necessary because the sibling packages automatically fall back to
 text mode if X is not active.

Source package