code: def step2(self, atv_pub_key, atv_salt):
          
          pk_str = binascii.hexlify(atv_pub_key).decode()
          salt = binascii.hexlify(atv_salt).decode()
          self._client_session_key, _, _ = self._session.process(pk_str, salt)
  
          if not self._session.verify_proof(self._session.key_proof_hash):
              raise exceptions.AuthenticationError('proofs do not match (mitm?)')
  
          pub_key = binascii.unhexlify(self._session.public)
          proof = binascii.unhexlify(self._session.key_proof)
          log_binary(_LOGGER, 'Client', Public=pub_key, Proof=proof)
          return pub_key, proof
docs: Second pairing step.