  A mix network by Wikstrom fails in correctness, provable privacy and
soundness. Its claimed advantages in security and efficiency are compromised.
The analysis in this paper illustrates that although the first two failures may
be fixed by modifying the shuffling protocol, the last one is too serious to
fix at a tolerable cost. Especially, an attack is proposed to show how easily
soundness of the shuffling scheme can be compromised. Moreover, the most
surprising discovery in this paper is that it is formally illustrated that in
practice it is impossible to fix soundness of the shuffling scheme by Wikstrom.
