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#!/usr/bin/env python3
import threading
import binascii
import re
import os
import time
import serial
import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk, Gdk, Pango, GLib
import hexnoise
class PairingWindow(Gtk.Window):
def __init__(self, noise, debug=False):
Gtk.Window.__init__(self, title='SecureHID pairing')
self.noise = noise
self.debug = debug
self.trusted = False
self.set_border_width(10)
self.set_default_size(600, 200)
self.vbox = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=10)
self.label = Gtk.Label()
self.label.set_line_wrap(True)
self.label.set_justify(Gtk.Justification.CENTER)
self.label.set_markup('<b>Step 1</b>\n\nContacting device...')
self.vbox.pack_start(self.label, True, True, 0)
self.entry = Gtk.Entry()
self.entry.set_editable(False)
self.vbox.pack_start(self.entry, True, True, 0)
self.confirm_button = Gtk.Button(label='Trust this device')
self.confirm_button.connect('clicked', self.confirm_trust)
self.confirm_button.set_sensitive(False)
self.abort_button = Gtk.Button(label='Abort')
self.abort_button.connect('clicked', lambda _foo: self.destroy())
self.bbox = Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL, spacing=10)
self.bbox.pack_start(self.confirm_button, True, True, 0)
self.bbox.pack_start(self.abort_button, True, True, 0)
self.vbox.pack_start(self.bbox, True, True, 0)
self.add(self.vbox)
self.handshaker = threading.Thread(target=self.pair, daemon=True)
self.handshaker.start()
def pair(self):
for i in range(10):
try:
self.run_handshake()
break
except hexnoise.ProtocolError as e:
print(e)
def run_handshake(self):
binding_incantation = self.noise.channel_binding_incantation()
GLib.idle_add(self.label.set_markup,
f'<b>Step 2</b>\n\nPerform channel binding ritual.\n'
f'Enter the following incantation, then press enter.\n'
f'<b>{binding_incantation}</b>')
def update_text(text):
self.entry.set_text(text)
self.entry.set_position(len(text))
clean = lambda s: re.sub('[^a-z0-9-]', '', s.lower())
if clean(binding_incantation).startswith(clean(text)):
color = 0.9, 1.0, 0.9 # light red
else:
color = 1.0, 0.9, 0.9 # light green
self.entry.override_background_color(Gtk.StateType.NORMAL, Gdk.RGBA(*color, 1.0))
try:
for user_input in self.noise.pairing_messages():
GLib.idle_add(update_text, user_input)
GLib.idle_add(self.finish_pairing)
except hexnoise.ProtocolError as e:
GLib.idle_add(self.label.set_markup, f'<b>Error: {e}</b>')
def finish_pairing(self):
self.label.set_markup(f'<b>Step 3</b>\n\nConfirm pairing.\n'
f'In case the device did not sound an alarm just now, confirm pairing now using the button below.')
self.confirm_button.set_sensitive(True)
def confirm_trust(self, _foo):
self.trusted = True
self.destroy()
class StatusIcon(Gtk.StatusIcon):
def __init__(self):
Gtk.StatusIcon.__init__(self)
self.set_tooltip_text('SecureHID connected')
self.set_from_file('secureusb_icon.png')
def run_pairing_gui(port, baudrate, debug=False):
XDG_CONFIG_HOME = os.environ.get('XDG_CONFIG_HOME') or os.path.join(os.path.expandvars('$HOME'), '.config', 'secure_hid')
if not os.path.isdir(XDG_CONFIG_HOME):
os.mkdir(XDG_CONFIG_HOME)
private_key_file = os.path.join(XDG_CONFIG_HOME, 'host_key.pem')
if not os.path.isfile(private_key_file):
with open(private_key_file, 'w') as f:
f.write(binascii.hexlify(hexnoise.NoiseEngine.generate_private_key_x25519()).decode())
known_devices_file = os.path.join(XDG_CONFIG_HOME, 'known_devices')
if not os.path.isfile(known_devices_file):
with open(known_devices_file, 'w') as f:
f.write('# This file contains the hex-encoded SHA-256 fingerprints of the X25519 keys of all trusted SecureHID devices\n')
with open(private_key_file) as f:
host_key_private = binascii.unhexlify(f.read())
ser = serial.Serial(port, baudrate)
packetizer = hexnoise.Packetizer(ser, debug=debug)
noise = hexnoise.NoiseEngine(host_key_private, packetizer, debug=debug)
noise.perform_handshake()
print('Connected.')
print('Device fingerprint:', noise.remote_fingerprint)
if not noise.paired:
window = PairingWindow(noise, debug=debug)
window.connect('destroy', Gtk.main_quit)
window.show_all()
Gtk.main()
if not window.trusted:
raise SystemError('User abort')
if not noise.paired:
raise SystemError('Unknown noise error')
with open(known_devices_file, 'a') as f:
f.write(f'{noise.remote_fingerprint} # added {time.ctime()}\n')
else:
with open(known_devices_file) as f:
known_devices = [ l.strip().partition('#')[0].strip() for l in f.readlines() if not l[0] == '#' ]
if noise.remote_fingerprint not in known_devices:
raise ValueError('Remote host is untrusted but seems to trust us.')
input_runner = threading.Thread(target=noise.uinput_passthrough, daemon=True)
input_runner.start()
status_icon = StatusIcon()
Gtk.main()
if __name__ == '__main__':
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('serial')
parser.add_argument('baudrate')
parser.add_argument('-d', '--debug', action='store_true')
args = parser.parse_args()
run_pairing_gui(args.serial, args.baudrate, args.debug)
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