  In this paper we review and comment on "A novel protocol-authentication
algorithm ruling out a man-in-the-middle attack in quantum cryptography", [M.
Peev et al., Int. J. Quant. Inform., 3, 225, (2005)]. In particular, we point
out that the proposed primitive is not secure when used in a generic protocol,
and needs additional authenticating properties of the surrounding
quantum-cryptographic protocol.
