docs: def get_hmac(self, key):
          """Returns the keyed HMAC for authentication of this state data.
  
          :param key: the key for the keyed hash function
          """
          h = HMAC.new(key, None, SHA256)
          h.update(self.iv)
          h.update(str(self.chunks).encode())
          h.update(self.f_key)
          h.update(self.alpha_key)
          h.update(str(self.encrypted).encode())
          return h.digest()