Increasing the security of the ping-pong protocol by using many mutually   unbiased bases
  In this paper we 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. We show that, by increasing the number of bases, it is possible to improve the security of this protocol. We also provide the upper bounds on eavesdropping average non-detection probability and propose a control mode modification that increases the attack detection probability. 
Piotr Zawadzki, Zbigniew Pucha{\l}a, Jaros{\l}aw Adam Miszczak
quant-ph cs.CR