pinentrygtk2

Pinentrygtk2 is a GTK+ 2 based graphical pinentry program used by GnuPG to securely prompt the user for a passphrase. It is part of the pinentry family, which provides a standard interface for entering private-key credentials through the gpg-agent while keeping the secret input out of shell and other processes.

Operation and design: When GnuPG requires a passphrase, gpg-agent launches pinentrygtk2 and communicates with it via the pinentry protocol. The program presents a small window with a prompt, a masked input field, and control buttons such as OK and Cancel. The input is not echoed to the display, and the dialog can convey the context of the request (for signing, decryption, or other key operations). It runs within the user's desktop environment and adheres to the GTK+ 2 look and feel.

Configuration and usage: To use pinentrygtk2, the pinentry-program setting in GnuPG’s configuration should point to the GTK2 build (for example pinentry-gtk2). It is one of several frontends, alongside pinentry-qt and pinentry-curses. In typical desktop setups, pinentrygtk2 integrates automatically with the session’s authentication prompts, provided the necessary GTK+ 2 libraries are installed.

License and distribution: Pinentrygtk2 is open-source software released under the GNU General Public License as part of the GnuPG project. It is maintained alongside other pinentry frontends and is distributed by many Linux distributions as a separate pinentry package.