def server():
"""Server listening on named pipes and serving forever."""
downlink = Connection('downlink', 'w+')
uplink = Connection('uplink', 'r')
cur_phase = 'INIT'
ffs_counter = [0]
# Listen for messages
for request in uplink.receive():
logger.debug('IN\t ' + request)
response, cur_phase = serve_request(request, cur_phase, ffs_counter)
if not response:
continue
downlink.send(response)
logger.debug('OUT\t ' + response)
downlink.close()
uplink.close()
def client():
"""Client mode work flow."""
downlink = Connection('downlink', 'r')
uplink = Connection('uplink', 'w+')
# Establish connection
dh = DiffieHellman()
p, g = dh.get_pg()
uplink.send('INIT,{0},{1}'.format(p, g))
response = get_response(downlink, 'MY_PUBLIC', 2,
'Failed to authenticate via DH')
public = dh.get_my_public()
uplink.send('MY_PUBLIC,{0}'.format(public))
key = dh.compute_shared(response[1])
logging.debug('Key established: {0}'.format(key.hexdigest()))
# Start encrypted communication
response = get_response(downlink, 'AES', 2, 'Failed to start AES')
aes = AES.new(key.digest(), AES.MODE_CBC, b64decode(response[1]))
# Verify identity using FFS
while True:
ffs = FFSProver()
# Send X
msg = msg_encrypt(aes, str(ffs.get_x()))
uplink.send('FFS_X,{0}'.format(msg))
# Get A vector
response = get_response(downlink, 'FFS_A', 2,
'Failed to verify identity via FFS')
a_vector = [int(a) for a in msg_decrypt(aes, response[1])]
# Solve Y
msg = msg_encrypt(aes, str(ffs.solve(a_vector)))
uplink.send('FFS_Y,{0}'.format(msg))
# Get result
response = next(downlink.receive())
if response not in ('FFS_OK', 'FFS_DONE'):
raise RuntimeError('Failed to verify identity via FFS')
if response == 'FFS_DONE':
break
# Send messages
print('Connection established, communication channel open.')
print('If you want to end this program press CTRL(C')
while True:
# Snd message
raw_msg = raw_input('Enter message: ')
msg = msg_encrypt(aes, raw_msg)
uplink.send('MSG,{0}'.format(msg))
# Get response
response = next(downlink.receive())
response = response.split(',')
if len(response) != 2 or response[0] != 'SHA256':
raise RuntimeError('Channel compromised')
# Compare Hashes
our_hash = sha256(raw_msg).hexdigest()
their_hash = msg_decrypt(aes, response[1])
print('Recieved: ' + their_hash)
if their_hash != our_hash:
print('Hash mismatch!')
raise RuntimeError('Channel compromised')
else:
print('Hash matches')
