The role of hierarchical entropy analysis in the detection and time-scale determination of covert timing channels

This paper evaluates the potential use of hierarchal entropy analysis to detect covert timing channels and determine the best time-scale that reveals it. A data transmission simulator is implemented to generate a collection of overt and covert channels. The hierarchical entropy analysis approach is then utilized to detect the covert timing channels and identify the type-scale that provides the highest evidence that the underlying channel is covert. Hierarchical entropy divides the stream of inter-arrival times greedily to identify the time-scale the best reveals the existence of a covert-timing channel. The lowest entropy in the sequence is the best indicator that identifies non-random patterns in the given data stream. The results show that hierarchal entropy analysis performs significantly better than the classical flat entropy approach in the detection of covert timing channels. Furthermore, the hierarchical entropy analysis provides details about the best time-scale that reveals the features of the covert timing channel.