Date Added: Apr 2012
In this paper, the authors propose an extended version of the ping-pong protocol and study its security. The proposed protocol incorporates the usage of mutually unbiased bases in the control mode. They show that, by increasing the number of bases, it is possible to improve the security of this protocol. They also provide the upper bounds on eavesdropping average non-detection probability and propose a control mode modification that increases the attack detection probability. A method of Quantum Secure Direct Communication (QSDC), contrary to Quantum Key Distribution (QKD) schemes, offers the confidential exchange of deterministic messages without key agreement.