Addendum to "Experimental demonstration of a quantum protocol for   Byzantine agreement and liar detection" arXiv:0710.0290
  Gao et al. [Phys. Rev. Lett. 101, 208901 (2008)] have described a possible intercept-resend attack for the quantum protocol for detectable Byzantine agreement in Phys. Rev. Lett. 100, 070504 (2008). Here we describe an extension of the protocol which defeats such attacks. 
Sascha Gaertner, Mohamed Bourennane, Christian Kurtsiefer, Adan   Cabello, Harald Weinfurter