Quantum Key Distribution and Communication using a Two-way Quantum Channel

We review a communication protocol recently proposed by us that makes use of a two-way quantum channel. We provide a characterization of such a protocol from a practical perspective, and consider the most relevant eavesdropping strategies against it. This allows us to compare its potentialities with those of a standard protocol which uses a one-way quantum channel.
Comment: Submitted in March 2009 to the special issue of Quantum Key Distribution in TCS and NACO