Comment on “Arbitrated quantum-signature scheme”
Marcos Curty, Norbert Lütkenhaus · Physical Review A · 2008
We investigate the quantum signature scheme proposed by and Zeng and Keitel [Phys. Rev. A 65, 042312 (2002)]. It uses Greenberger-Horne-Zeilinger 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.