In this work we review the security vulnerability of Quantum Cryptography
with respect to "man-in-the-middle attacks" and the standard authentication
methods applied to counteract these attacks. We further propose a modified
authentication algorithm which features higher efficiency with respect to
consumption of mutual secret bits.Comment: 4 pages, submitted to the International Journal of Quantum
Information, Proceedings of the meeting "Foundations of Quantum Information",
Camerino, April 200