QUANTUM COMMUNICATION BETWEEN ANONYMOUS SENDER AND ANONYMOUS RECEIVER IN THE PRESENCE OF STRONG ADVERSARY.

While many scenarios of anonymous communication can be solved by various famous classical techniques including mix nets or dining cryptographers (DC), an abundant amount of anonymous tasks remains open. In this paper, we present a solution to one such task. Our protocol serves as a private communication channel for quantum messages while ensuring that both the sender and the receiver stay anonymous in a set of all parties. Our protocol is a continuation of our previous work on anonymous transmission of quantum information. The protocol does not require trusted parties, and is secure against an active adversary. It can also withstand denial of service attacks. The protocol exhibits an advantage of quantum resources over classical because no classical solution is known (in the same security settings). Entanglement swapping technique is used to create "symmetry" in the protocol, which makes it very transparent and easier to analyze. The security analysis we present is heavily based on our previous work on quantum anonymous communication. The task we implement is also a nice illustration of a cryptographic task where two parties in a multi-party protocol can be dishonest at the same time, but are not cooperating. [ABSTRACT FROM AUTHOR]