insecure-lock - Screen locker in pure Emacs Lisp

insecure-lock is an extensible screen lock framework. It is implemented within Emacs itself rather than interfacing with underlying window system, so it is best used together with EXWM as a screen locker. Otherwise, it can be used as a screen saver.

As its name suggest, currently security is not a strength of this package. It’s more of an advice rather than defense against your intruders. Nevertheless, any suggestions about improving security are more than welcomed!

Gallery

(setq 'insecure-lock-mode-hook '(insecure-lock-redact insecure-lock-posframe))

(setq insecure-lock-mode-hook '(vampire-time-screensaver insecure-lock-blank-screen)) (vampire-time-screensaver is a function for my personal use, haven’t been published yet. Curious people may check my .emacs.d.)

(setq insecure-lock-mode-hook '(insecure-lock-blank-screen insecure-lock-posframe)), with some tweaks to insecure-lock-blank-screen-face and insecure-lock-posframe-parameters

Configuration

Add the following lines to your init.el

(require 'insecure-lock)
(insecure-lock-run-idle 300) ;; Lock screen after 300 seconds
(require 'posframe)
(setq 'insecure-lock-mode-hook '(insecure-lock-blank-screen insecure-lock-posframe)) ;; Enable date time display

Note that currently insecure-lock is not very robust against errors from modules. To avoid hanging your Emacs session because of misconfiguration, it’s strongly advised to try your new configurations in a separate Emacs instance before using it in your main Emacs session!

Variables for customization

insecure-lock-require-password

If set, intercept input events and require login password to unlock. Otherwise unlock with any key stroke, acting more like a screen saver.

insecure-lock-mode-hook

You can turn on screen lock “modules” by adding functions to this variable. The default value is (insecure-lock-blank-screen).

The order of modules matters! For example, usually you want to put insecure-lock-posframe after the rest so that the posframe doesn’t get blanked/redacted.

Available “modules” (in fact just plain functions):

insecure-lock-blank-screen

Display a blank buffer without modeline in place of any displaying buffers/windows.

insecure-lock-redact

Available only if the redacted package is loaded. Turn on redact-mode and disable mode line on any displaying buffer.

insecure-lock-posframe

Available only if the posframe package is loaded. Display a posframe to show some status. This can be customized by:

insecure-lock-posframe-parameters

Parameters to the posframe.

insecure-lock-posframe-update-function

Function to populate the posframe. The default one, insecure-lock-posframe-default-update-function, shows current time and date in two lines, padded and centered. It’s a good starting point for writing your own snippet!

Writing a module

A primary goal for insecure-lock is to be composable and extensible. It should be quite easy to get hands on extending insecure-lock. Start Writing your module for your own amusement! And contribute to spread the joy!

An example insecure-lock module

A minimal example of a insecure-lock module:

(defvar blackout--saved-background-color nil)
(defun blackout ()
  (if insecure-lock-mode
      (progn
        (setq blackout--saved-background-color (face-background 'default))
        (set-background-color "black"))
    (set-background-color blackout--saved-background-color))

You can enable it via (add-hook 'insecure-lock-mode-hook 'blackout). This sets Emacs background color to black when screen is locked, and recover the original background color when unlocked.

In general, a module look like:

(defun my-module ()
  (if insecure-lock-mode
      '(code to setup when entering screen lock)
    '(code to clean up when leaving screen lock))

Useful Variables

insecure-lock-update-functions

Add periodic update functions for your module to this variable! The insecure-lock-update-timer will call functions in this list every insecure-lock-update-timer-interval seconds (default to 1).

(defun my-module-update ()
  '(code to update display))
(defun my-module ()
  (if insecure-lock-mode
      (progn
        (add-hook 'insecure-lock-update-functions 'my-module-update)
        '(code to setup when entering screen lock))
    '(code to clean up when leaving screen lock))
    

There’s no need to bother removing the update functions when cleanup. insecure-lock-update-functions will be set to nil at the beginning of screen lock setup.