def __init__(self):
# TODO: Maybe we should add dict as ParticleProtocol inheritance?
self._transport = None
self._step = None
self._device_id = None
self._device_id_hex = None
self._device_key = None
self._nonce = None
self._aes_key = None
self._iv = None
self._salt = None
self._counter = 0
self._crypto = CryptoOsCrypto()
# Load server key
logging.debug("Loading server key from: %s" % args.private_key_file)
self._crypto.load_server_key(args.private_key_file)
super().__init__()
class ParticleProtocol(asyncio.Protocol):
"""
This is wrapper that implement:
* handshake as describe here: https://github.com/spark/spark-protocol/blob/master/js/lib/Handshake.js#L29
"""
def __init__(self):
# TODO: Maybe we should add dict as ParticleProtocol inheritance?
self._transport = None
self._step = None
self._device_id = None
self._device_id_hex = None
self._device_key = None
self._nonce = None
self._aes_key = None
self._iv = None
self._salt = None
self._counter = 0
self._crypto = CryptoOsCrypto()
# Load server key
logging.debug("Loading server key from: %s" % args.private_key_file)
self._crypto.load_server_key(args.private_key_file)
super().__init__()
def connection_made(self, transport):
# Handshake step 1: Socket opens.
logging.debug("Client connection from %s" % transport.get_extra_info('peername')[0])
self._transport = transport
self._step = 0
self._nonce = self._crypto.random(40)
# Handshake step 2: Server responds with 40 bytes of random data as a nonce.
if self._step == 0:
logging.debug("Generated nonce: %s" % self._nonce)
self.write(self._nonce)
self._step += 1
def connection_lost(self, exc):
logging.debug("Connection lost with device ID: %s (%s)" %
(self._device_id_hex, self._transport.get_extra_info('peername')[0]))
def data_received(self, data):
logging.debug("Data received (%s) %s: %s" % (self._step, len(data), data))
if self._step == 1:
cipher = None
# Handshake step 3: Server should read exactly 256 bytes from the socket.
if len(data) != 256:
logging.critical("Not enough data received from core in handshake step #3")
self._transport.close()
try:
cipher = self._crypto.rsa_pkcs1v15_decrypt(data)
except ValueError:
self._transport.close()
# The first 40 bytes of the message must match the previously sent nonce,
# otherwise Server must close the connection.
#
# Remaining 12 bytes of message represent STM32 ID.
(_client_nonce, self._device_id) = (cipher[:40], cipher[40:52])
if _client_nonce != self._nonce:
logging.critical("Invalid nonce received, closing connection.")
self._transport.close()
# Store an hexadecimal string of device ID
self._device_id_hex = binascii.hexlify(self._device_id).decode()
logging.debug("Loading device public key from %s/%s.pem" % (args.devices_keys, self._device_id_hex))
# Server looks up STM32 ID, retrieving the Core's public RSA key.
try:
self._crypto.load_device_key("%s/%s.pem" % (args.devices_keys, self._device_id_hex))
# TODO: Check key size
# If the public key is not found, Server must close the connection.
except Exception:
logging.critical("Device ID %s public key not found, closing connection" % self._device_id_hex)
self._transport.close()
logging.info("Device ID %s connected" % self._device_id_hex)
# Handshake step 4: Server creates secure session key
# Server generates 40 bytes of secure random data to serve
# as components of a session key for AES-128-CBC encryption.
session_key = self._crypto.random(40)
# The first 16 bytes (MSB first) will be the key, the next 16 bytes (MSB first) will be the
# initialization vector (IV), and the final 8 bytes (MSB first) will be the salt.
(self._aes_key, self._iv, self._salt) = (session_key[:16], session_key[16:32], session_key[-8:])
logging.debug("AES KEY: %s, IV: %s, SALT: %s" % (self._aes_key, self._iv, self._salt))
# Server RSA encrypts this 40-byte message using the Core's public key to create a 128-byte ciphertext.
cipher = self._crypto.rsa_pkcs1v15_encrypt(session_key)
logging.debug("Cipher size: %s" % len(cipher))
# Server creates a 20-byte HMAC of the ciphertext using SHA1 and the 40 bytes generated
# in the previous step as the HMAC key.
hmac_result = self._crypto.hmac(session_key, cipher, CryptographicMeta.SHA1)
logging.debug("HMAC (size: %s): %s" % (len(hmac_result), hmac_result))
# Server signs the HMAC with its RSA private key generating a 256-byte signature.
signature = self._crypto.rsa_pkcs1v15_sign(hmac_result)
# Server sends 384 bytes to Core: the ciphertext then the signature.
self.write(cipher + signature)
self._step += 1
elif self._step == 2:
logging.debug("hello received from %s" % self._device_id_hex)
# Decrypt data from hello
(a, b, cipherdata) = (data[0], data[1], data[2::])
hello_message = self._crypto.aes_decrypt(self._aes_key, cipherdata, self._iv)
logging.debug("Hello message: %s %s %s"
% (a,
b,
binascii.hexlify(hello_message)))
# Send our hello
self._step += 1
elif self._step > 3:
return self.protocol_received(data)
def write(self, data):
logging.debug("Sending %s bytes to %s (%s), step: %s" % (
len(data),
self._device_id_hex,
self._transport.get_extra_info('peername')[0],
self._step
))
self._transport.write(data)
def protocol_received(self, data):
raise NotImplementedError
