Quantum authentication using entangled state

A scheme of quantum authentication is presented. Two parties share Einstein-Podolsky-Rosen (EPR) pairs previously as the authentication key which servers as encoder and decoder. The authentication is accomplished with local controlled-NOT operations and unitary rotations. It is shown that our scheme is secure even in the presence of an eavesdropper who has complete control over both classical and quantum channels. Another character of this protocol is that the EPR sources are reusable. The robustness of this protocol is also discussed.