A NOTE ON AN ARBITRATED QUANTUM SIGNATURE SCHEME
Zeng and Keitel proposed an arbitrated quantum signature scheme in 2002. Recently, Curty and Lutkenhaus pointed out that the protocol is not operationally specified. In a reply, Zeng gave more details of the scheme. The author also claimed that the scheme is suitable for unknown messages. In this letter, we remark that the invented scenario in the original scheme is artificial. This is because its security entirely depends on the presence of a trustworthy arbitrator. Moreover, the claim that the original scheme is suitable for unknown messages is not sound.
arbitrator quantum digital signature blind signature