Timing capacity of queues with random arrival and modified service times

A queue timing channel with random arrival and service times is investigated. The message is encoded into a sequence of additional delays that packets are subject to before they depart from the queue. We derive upper and lower bounds of the channel capacity for general arrival and service processes, and general load. We establish the channel capacity for the queue with exponential server and no load constraint by keeping the queue stable. We discuss the consequences of this result and describe a possible application where the timing channel is used to send covert information.