Comment on „Secure direct communication with a quantum one-time pad“

In the paper [Phys. Rev. A 69, 052319 (2004)], a quantum direct communication protocol is proposed which is claimed to be unconditionally secure even for the case of a noisy channel. We show that this is not the case by giving an undetectable attack scheme.

Phys. Rev. A 72, 016301 – Published 11 July 2005

Preprint: arXiv:quant-ph/0406115