def step4(self, encrypted_data): """Last pairing step.""" chacha = chacha20.Chacha20Cipher(self._session_key, self._session_key) decrypted_tlv_bytes = chacha.decrypt(encrypted_data, nounce="PS-Msg06".encode()) if not decrypted_tlv_bytes: raise exceptions.AuthenticationError("data decrypt failed") decrypted_tlv = hap_tlv8.read_tlv(decrypted_tlv_bytes) _LOGGER.debug("PS-Msg06: %s", decrypted_tlv) atv_identifier = decrypted_tlv[TlvValue.Identifier] atv_signature = decrypted_tlv[TlvValue.Signature] atv_pub_key = decrypted_tlv[TlvValue.PublicKey] log_binary( _LOGGER, "Device", Identifier=atv_identifier, Signature=atv_signature, Public=atv_pub_key, ) # TODO: verify signature here return HapCredentials( atv_pub_key, self._auth_private, atv_identifier, self.pairing_id )
def _get_pairing_data(message: Dict[str, object]): pairing_data = message.get(PAIRING_DATA_KEY) if not pairing_data: raise exceptions.AuthenticationError("no pairing data in message") if not isinstance(pairing_data, bytes): raise exceptions.ProtocolError( f"Pairing data has unexpected type: {type(pairing_data)}") tlv = read_tlv(pairing_data) if TlvValue.Error in tlv: raise exceptions.AuthenticationError(stringify(tlv)) return tlv
def handle_crypto_pairing(self, message, inner): """Handle incoming crypto pairing message.""" _LOGGER.debug("Received crypto pairing message") pairing_data = read_tlv(inner.pairingData) seqno = pairing_data[TlvValue.SeqNo][0] # Work-around for now to support "tries" to auth before pairing if seqno == 1: if TlvValue.PublicKey in pairing_data: self.has_paired = True elif TlvValue.Method in pairing_data: self.has_paired = False suffix = "paired" if self.has_paired else "pairing" method = "_seqno{0}_{1}".format(seqno, suffix) getattr(self, method)(pairing_data)
def verify1(self, credentials, session_pub_key, encrypted): """First verification step.""" self._shared = self._verify_private.exchange( X25519PublicKey.from_public_bytes(session_pub_key) ) session_key = hkdf_expand( "Pair-Verify-Encrypt-Salt", "Pair-Verify-Encrypt-Info", self._shared ) chacha = chacha20.Chacha20Cipher(session_key, session_key) decrypted_tlv = hap_tlv8.read_tlv( chacha.decrypt(encrypted, nounce="PV-Msg02".encode()) ) identifier = decrypted_tlv[TlvValue.Identifier] signature = decrypted_tlv[TlvValue.Signature] if identifier != credentials.atv_id: raise exceptions.AuthenticationError("incorrect device response") info = session_pub_key + bytes(identifier) + self._public_bytes ltpk = Ed25519PublicKey.from_public_bytes(bytes(credentials.ltpk)) try: ltpk.verify(bytes(signature), bytes(info)) except InvalidSignature as ex: raise exceptions.AuthenticationError("signature error") from ex device_info = self._public_bytes + credentials.client_id + session_pub_key device_signature = Ed25519PrivateKey.from_private_bytes(credentials.ltsk).sign( device_info ) tlv = hap_tlv8.write_tlv( { TlvValue.Identifier: credentials.client_id, TlvValue.Signature: device_signature, } ) return chacha.encrypt(tlv, nounce="PV-Msg03".encode())
def test_read_key_larger_than_255_bytes(): assert read_tlv(LARGE_KEY_OUT) == LARGE_KEY_IN
def test_read_two_keys(): assert read_tlv(DOUBLE_KEY_OUT) == DOUBLE_KEY_IN
def test_read_single_key(): assert read_tlv(SINGLE_KEY_OUT) == SINGLE_KEY_IN
def _get_pairing_data(resp): tlv = read_tlv(resp.inner().pairingData) if TlvValue.Error in tlv: raise exceptions.AuthenticationError(stringify(tlv)) return tlv