AwesomeWM

This will be a quick example of how we can wire up yubikey-touch-detector to AwesomeWM widgets. First we set up a watcher that will emit when a touch is expected and a widget that subscribes and changes its color on the events. The sky is the limit with Awesome widgets and hopefully this is a good starting point in your dotfiles.

First create the watcher that will emit the signals along with the event and context of the event.

signal: "yubikey"
  event: "start" or "stop"
  context: "GPG" or "U2F"

This has the only external dependency which is openbsd-netcat, which gives us the -U flag

local awful = require 'awful'
local naughty = require 'naughty'

-- Calling `echo` produces a newline which the awesome callback needs to process line by line
local event_stream = [[ bash -c '
  nc -U $XDG_RUNTIME_DIR/yubikey-touch-detector.socket | while read -n5 cmd; do
    echo $cmd
  done
']]

awful.spawn.with_line_callback(event_stream, {
  stdout = function(line)
    local event, context
    -- U2F
    if line:match("U2F") then
      context = "U2F"
      -- started waiting
      if line:match("_1") then
        event = "start"
      else
        event = "stop"
      end
    -- GPG
    else
      context = "GPG"
      -- started waiting
      if line:match("_1") then
        event = "start"
      else
        event = "stop"
      end
    end

    awesome.emit_signal("yubikey", event, context)
  end,
  stderr = function(line)
    naughty.notify({ title = "Yubikey Watcher Failure", text = line })
  end
})

Now for the widget that subscribes to the signal and updates its background color when a touch is expected. In this example the context arg of the signal won't get used but it is there if you'd like to incorporate it.

local wibox = require 'wibox'
local gfs = require 'gears.filesystem'
local gc = require 'gears.color'

-- SVG or PNG image works best in this example
local icon = "path/to/an/icon"

local white_icon = gc.recolor_image(icon, "#FFF")
local yellow_icon = gc.recolor_image(icon, "#FFE6B3")

local yubikey = wibox.widget {
  image = white_icon,
  widget = wibox.widget.imagebox,
  resize = true
}

-- change the icon color when based on if a touch is expected or not
awesome.connect_signal("yubikey", function (event)
  local new_icon
  if event == "start" then
    new_icon = yellow_icon
  else
    new_icon = white_icon
  end
  yubikey.image = new_icon
end)

return yubikey