Secure coding over networks

In this paper we study the problem of secure communication over a network in which each link may be noisy or noiseless. A single-source single-sink acyclic planar network is considered, and the communication between the source and the sink is subject to non-cooperating eavesdropping on each link. Sufficient conditions, in terms of communication rates and network parameters, are found for provable secure communication, along with an intuitive and efficient coding scheme. The derived achievable rate equivocation region is tight when specializing to several special cases.