On secure network coding with uniform wiretap sets
  This paper shows determining the secrecy capacity of a unicast network with uniform wiretap sets is at least as difficult as the k-unicast problem. In particular, we show that a general k-unicast problem can be reduced to the problem of finding the secrecy capacity of a corresponding single unicast network with uniform link capacities and one arbitrary wiretap link. 
Wentao Huang and Tracey Ho and Michael Langberg and Joerg Kliewer
cs.IT math.IT