 If Alice and Bob have an initial shared secret then they can use an unconditionally secure authentication scheme (such as Carter-Wegman,) along with quantum key distribution to exponentially expand this key, using a small amount of the new key to authenticate the next session.Several methods to create this initial shared secret have been proposed, for example using a 3rd party or chaos theory.Nevertheless, only "almost strongly universal" family of hash functions can be used for unconditionally secure authentication.