We investigate the quantum signature scheme proposed by Zeng and Keitel [Phys. Rev. A 65, 042312 (2002)]. It uses Greenberger-Horne-Zeilinger (GHZ) states and the availability of a trusted arbitrator. However, in our opinion the protocol is not clearly operationally defined and several steps are ambiguous. Moreover, we argue that the security statements claimed by the authors are incorrect.
Cite
@article{arxiv.0806.0854,
title = {Comment on "Arbitrated quantum-signature scheme"},
author = {Marcos Curty and Norbert Lütkenhaus},
journal= {arXiv preprint arXiv:0806.0854},
year = {2009}
}