Man-in-the-Middle Attack on “Quantum Dialogue with Authentication Based on Bell States”

Recently, Shen et al . (Int. J. Theor. Phys. doi: 10.1007/s10773-012-1276-6 , 2012 ) proposed a quantum dialogue with authentication protocol based on Bell states. This study points out that Shen et al .’s protocol suffers from a man-in-the-middle attack. By manipulating the photons and classical information transmitted between two communicants, an attacker can not only pass the mutual identity authentication, but also obtain their secret messages and new authentication keys without being detected.