Need help with yubikey-touch-detector?
Click the “chat” button below for chat support from the developer who created it, or find similar developers for support.

About the developer

maximbaz
220 Stars 14 Forks ISC License 96 Commits 1 Opened issues

Description

A tool to detect when your YubiKey is waiting for a touch (to send notification or display a visual indicator on the screen)

Services available

!
?

Need anything else?

Contributors list

# 15,014
ip-addr...
Arch Li...
Electro...
Zsh
87 commits
# 83,419
Shell
Linux
Laravel
vps
1 commit
# 108,310
dunst
i3bar
Lua
Arch Li...
1 commit
# 193,851
Sass
Shell
Laravel
php7
1 commit
# 204,701
Shell
exploit...
isolati...
nix
1 commit
# 87,126
Go
php7
gtk
ceph
1 commit
# 74,086
regex
Rust
parser-...
Flask
1 commit
# 151,770
openapi
godoc
Google ...
googlec...
1 commit

YubiKey touch detector

This is a tool that can detect when YubiKey is waiting for your touch. It is designed to be integrated with other UI components to display a visible indicator.

For example, an integration with i3wm and py3status looks like this:

demo

See also: FAQ: Which UI components are already integrated with this app?

Installation

This tool only works on Linux. If you want to help implementing (at least partial) support for other OS, pull requests are very welcome!

On Arch Linux, you can install it with

pacman -S yubikey-touch-detector

The package also installs a systemd service and socket. If you want the app to launch on startup, just enable the service like so:

$ systemctl --user daemon-reload
$ systemctl --user enable --now yubikey-touch-detector.service

If you want the service to be started only when there is a listener on Unix socket, enable the socket instead like so:

$ systemctl --user daemon-reload
$ systemctl --user enable --now yubikey-touch-detector.socket

Alternatively you can download the latest release from the GitHub releases page. All releases are signed with my PGP key.

Finally you can install the app with

go
:
$ go get -u github.com/maximbaz/yubikey-touch-detector

This places the binary in your

$GOPATH/bin
folder, as well as the sources in
$GOPATH/src
for you to use the detection functions in your own code.

Usage

Command line

To test how the app works, run it in verbose mode to print every event on STDERR:

$ yubikey-touch-detector -v

Now try different commands that require a physical touch and see if the app can successfully detect them.

Desktop notifications

You can make the app show desktop notifications using

libnotify
if you run it with corresponding flag:
$ yubikey-touch-detector --libnotify

Configuring the app

The app supports the following environment variables and CLI arguments (CLI args take precedence):

| Environment var | CLI arg | | ---------------------------------- | ------------- | |

YUBIKEY_TOUCH_DETECTOR_VERBOSE
|
-v
| |
YUBIKEY_TOUCH_DETECTOR_LIBNOTIFY
|
--libnotify
|

You can configure the systemd service by defining any of these environment variables in

$XDG_CONFIG_HOME/yubikey-touch-detector/service.conf
, e.g. like so:
YUBIKEY_TOUCH_DETECTOR_VERBOSE=true
YUBIKEY_TOUCH_DETECTOR_LIBNOTIFY=true

Integrating with other UI components

First of all, make sure the app is always running (e.g. start a provided systemd user service or socket).

Next, in order to integrate the app with other UI components to display a visible indicator, use any of the available notifiers in the

notifier
subpackage.
notifier/unix_socket

unix_socket
notifier allows anyone to connect to the socket
$XDG_RUNTIME_DIR/yubikey-touch-detector.socket
and receive the following events:

| event | description | | ------- | -------------------------------------------------- | |

GPG_1
| when a
gpg
operation started waiting for a touch | |
GPG_0
| when a
gpg
operation stopped waiting for a touch | |
U2F_1
| when a
u2f
operation started waiting for a touch | |
U2F_0
| when a
u2f
operation stopped waiting for a touch |

All messages have a fixed length of 5 bytes to simplify the code on the receiving side.

How it works

Your YubiKey may require a physical touch to confirm these operations:

  • sudo
    request (via
    pam-u2f
    )
  • WebAuthn
  • gpg --sign
  • gpg --decrypt
  • ssh
    to a remote host (and related operations, such as
    scp
    ,
    rsync
    , etc.)
  • ssh
    on a remote host to a different remote host (via forwarded
    ssh-agent
    )

See also: FAQ: How do I configure my YubiKey to require a physical touch?

Detecting u2f operations

In order to detect whether a U2F/FIDO2 operation requests a touch on YubiKey, the app is listening on the appropriate

/dev/hidraw*
device for corresponding messages as per FIDO spec.

See

detector/u2f.go
for more info on implementation details, the source code is documented and contains relevant links to the spec.

Detecting gpg operations

This detection is based on a "busy check" - when the card is busy (i.e.

gpg --card-status
hangs), it is assumed that it is waiting on a touch. This of course leads to false positives, when the card is busy for other reasons, but it is a good guess anyway.

In order to not run the

gpg --card-status
indefinitely (which leads to YubiKey be constantly blinking), the check is being performed only after
$GNUPGHOME/pubring.kbx
(or
$HOME/.gnupg/pubring.kbx
) file is opened (the app is thus watching for
OPEN
events on that file).

If the path to your

pubring.kbx
file differs, define
$GNUPGHOME
environment variable, globally or in
$XDG_CONFIG_HOME/yubikey-touch-detector/service.conf
.

Detecting ssh operations

The requests performed on a local host will be captured by the

gpg
detector. However, in order to detect the use of forwarded
ssh-agent
on a remote host, an additional detector was introduced.

This detector runs as a proxy on the

$SSH_AUTH_SOCK
, it listens to all communications with that socket and starts a
gpg --card-status
check in case an event was captured.

FAQ

How do I configure my YubiKey to require a physical touch?

For

sudo
requests with
pam-u2f
, please refer to the documentation on Yubico/pam-u2f and online guides (e.g. official one).

For

gpg
and
ssh
operations, install ykman and use the following commands:
$ ykman openpgp set-touch sig on   # For sign operations
$ ykman openpgp set-touch enc on   # For decrypt operations
$ ykman openpgp set-touch aut on   # For ssh operations

If you are going to frequently use OpenPGP operations,

cached
or
cached-fixed
may be better for you. See more details here.

Make sure to unplug and plug back in your YubiKey after changing any of the options above.

Which UI components are already integrated with this app?

We use cookies. If you continue to browse the site, you agree to the use of cookies. For more information on our use of cookies please see our Privacy Policy.