Variable noise effects upon a simple timing channel

Investigates the effects of noise upon a simple timing channel. Shannon´s information theory (C. Shannon et al., 1949) is used to quantify the resulting information flow across the channel. In particular the author studies how a probabilistic response time to a query by a low user affects the mutual information and channel capacity. He claims that we will never eliminate all covert channels in a multi-user computer system without serious degradation of performance. Therefore, it is important to know how `bad´ the covert channels are. One way to do this is through an information theoretic capacity analysis