A quasi quantum secure direct communication protocol with authentication

The quantum communication is a new-style communication scheme based on quantum mechanics. It arouses much interest recently. In this paper, a novel quantum secure communication protocol is proposed. This is a quasi quantum secure direct communication protocol, since it closely unites the quantum key distribution and the classical communication. In the protocol, a key is distributed between both parties participating in communication using EPR pairs, the secret message is sent through classical public channel and the both are closely combined. The protocol applies a braid-based key agreement protocol to let both parties share a secret random number, whose size and magnitude are undecided in advance. It is used to perform all the authentications of the communication. So the communication is simplified. The security of the proposed protocol is based on the no-cloning theorem and the fact that the p-th root finding problem on braid groups is intractable even on quantum computers, as well as classical computers.