Combining XMonad with pass
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Recently, I’ve resolved to stop reusing the same password over and over again on every website that I’m registered on. Of course, remembering a new password for every website is extremely difficult, especially if you generate them randomly.

This is where password managers come in. Typically, these applications manage a password database that is secured with a master password. pass is one such program that I’m particularly fond of. It’s a very minimal command line utility that uses gpg to encrypt your passwords and (optionally) git for tracking changes and creating backups. You can generate and save a password with

$ pass generate [name] [length]

and copy a password to the clipboard with

$ pass -c [name]

It’s great when working on the command line, but is a bit inconvenient when you’re entering passwords on the web, because you have to switch to a terminal to use it.

XMonad is my favourite tiling window manager. It is configured in Haskell and is extremely convenient for programming and working in the terminal. It occured to me that XMonad can be easily extended to interface with applications like pass. The xmonad-contrib package includes scaffolding for creating custom prompts that query the user for input and offer tab completion.

Include the following Modules in your ~/.xmonad/xmonad.hs:

import System.Environment
import System.FilePath.Posix
import XMonad.Prompt

A new barebones prompt can be configured in a few lines of code:

data Pass = Pass

instance XPrompt Pass where
  showXPrompt       Pass = "Pass: "
  commandToComplete _ c  = c
  nextCompletion      _  = getNextCompletion

passPrompt :: XPConfig -> X ()
passPrompt c = do
  li <- io getPasswords
  mkXPrompt Pass c (mkComplFunFromList li) selectPassword

Now, we need functions for interfacing with pass:

selectPassword :: String -> X ()
selectPassword s = spawn $ "pass -c " ++ s

getPasswords :: IO [String]
getPasswords = do
  user <- getEnv "USER"
  entries <- getDirectoryContents $
    "/home/" ++ user ++ "/.password-store"
  return $ map takeBaseName entries

Bind a key to passPrompt promptConfig for opening the prompt.

Finally, the prompt can be styled to your liking:

promptConfig = defaultXPConfig
  { font        = "xft:Source Code Pro:pixelsize=12"
  , borderColor = "#1e2320"
  , fgColor     = "#dddddd"
  , fgHLight    = "#ffffff"
  , bgColor     = "#1e2320"
  , bgHLight    = "#5f5f5f"
  , height      = 18
  , position    = Top

The Pass: prompt autocompletes the names in the password database and makes working with pass extremely convenient.

Please note that in the code snippet above, only top-level passords in ~/.password-store are included in the list of options. This could be extended by recursing into subdirectories in getPasswords.

This example could easily be used to implement other custom prompts. Give it a try!

You can find my complete XMonad configuration on Github.

edit (2015-04-12): It seems that this post has inspired the new XMonad.Prompt.Pass module in xmonad-contrib. It features many improvements over the above implementation and I recommend everyone to use it instead. Thanks for putting in the work!