async def start_pairing(self):
        """Start pairing procedure."""
        self.srp.initialize()

        msg = messages.crypto_pairing({
            tlv8.TLV_METHOD: b'\x00',
            tlv8.TLV_SEQ_NO: b'\x01'})
        resp = await self.protocol.send_and_receive(
            msg, generate_identifier=False)

        pairing_data = _get_pairing_data(resp)

        if tlv8.TLV_BACK_OFF in pairing_data:
            time = int.from_bytes(
                pairing_data[tlv8.TLV_BACK_OFF], byteorder='big')
            raise Exception('back off {0}s'.format(time))

        self._atv_salt = pairing_data[tlv8.TLV_SALT]
        self._atv_pub_key = pairing_data[tlv8.TLV_PUBLIC_KEY]
Start pairing procedure.