Analysis on Security Loophole of Two-Step Efficient Quantum Dialogue with Three-Particle Entangled W State.

Very recently, Yin and Tang proposed a two-step efficient quantum dialogue (QD) protocol with three-particle entangled W state (Yin and Tang Int. J. Theor. Phys. 53, 2760 ). In this Letter, the security loophole named information leakage, i.e., anybody else can elicit partial information of secret messages without any active attack, is discovered and deduced in detail. Furthermore, the essence of information leakage is studied from the viewpoint of Holevo theorem. [ABSTRACT FROM AUTHOR]