Eavesdropping on the quantum dialogue protocol in lossy channel

We present an improved eavesdropping scheme on the quantum dialogue protocol in lossy channel, which is based on the strategies of Wójcik Phys. Rev. Lett. 90 157901 (2003)] and ZML Phys. Lett. A 333 46 (2004)] attack schemes. We show that our attack scheme doubles the domain of Eve's eavesdropping and Eve can gain more information of the communication with less risk of being detected. Finally, a possible improvement for the dialogue protocol security is proposed.