g2ftool : U2F command line interface tool

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g2ftool is a command line tool to interact with U2FHID devices, whether physical devices or the virtual one provided by u2fd.


The tool can send basic commands such as ping, raw messages, as well as more complex commands such as register and authenticate.

For all commands, a device must be specified, this will typically be something like /dev/hidraw3.

Basic Command Examples

To send a U2F_PING command:

g2ftool --dev=/dev/hidraw<n> --ping

You may like to increase verbosity to see details of the messages sent:

g2ftool --dev=/dev/hidraw<n> --v=3 --ping


Sends a U2F_REGISTER message.

g2ftool --dev=/dev/hidraw<n> --reg --application=<sha256(app)>

Output will include a key_handle for this new registration.


Sends a U2F_AUTHENTICATE message.

g2ftool --dev=/dev/hidraw<n> --auth
                             --application=<value provided at registration>
                             --challenge=<value provided at registration>
                             --key_handle<value returned after registration>