Topological quantum computation provides efficiency with fault-tolerant and error-correction to overcome decoherence
problem. Here we investigate a class of topological quantum computation device. We discuss a method
of constructing topological quantum scheme based on quantum walk for the state space.
Based on the law of quantum mechanics we present a simple authorization scheme:
Quauth. The description of the scheme is given in details. The authorization is
accomplished through a quantum channel by one way communication. We show that
eavesdropper gets no information about key no matter how many times s/he is listening
on the channel. The scheme is robust against both the passive and active attacks. By
induction we prove that the scheme is information theoretically secure.
If an eavesdropper Eve is equipped with quantum computers, she can easily break the public key exchange protocols used today. In this paper we will discuss the post-quantum Diffie-Hellman key exchange and private key exchange protocols.