Robust Network Coding in the Presence of Untrusted Nodes

While network coding can be an efficient means of information dissemination in networks, it is highly susceptible to “pollution attacks,” as the injection of even a single erroneous packet has the potential to corrupt each and every packet received by a given destination. Even when suitable error-control coding is applied, an adversary can, in many interesting practical situations, overwhelm the error-correcting capability of the code. To limit the power of potential adversaries, a broadcast transformation is introduced, in which nodes are limited to just a single (broadcast) transmission per generation. Under this broadcast transformation, the multicast capacity of a network is changed (in general reduced) from the number of edge-disjoint paths between source and sink to the number of internally disjoint paths. Exploiting this fact, a family of networks is proposed whose capacity is largely unaffected by a broadcast transformation. This results in a significant achievable transmission rate for such networks, even in the presence of adversaries.