We consider the problem of covert communication over a state-dependent channel, where the transmitter has causal or noncausal knowledge of the channel states. Here, “covert” means that a warden on the channel should observe similar statistics when the transmitter is sending a message and when it is not. When a sufficiently long secret key is shared between the transmitter and the receiver, we d...

Covert channels have the unique quality of masking evidence that a communication has ever occurred between two parties. For spies and terrorist cells, this quality can be the difference between life and death. However, even the detection of communications in a botnet could be troublesome for its creators. To evade detection and prevent insights into the size and members of a botnet, covert chan...

Network covert channel is a technology that transfers information secretly through the computer network. The length-based covert channel is one of the most popular covert channels. Most of the existing length-based schemes are vulnerable to detections due to the abnormal statistical features of the covert traffic. In this paper, a Skype-based length covert channel SkyLen is proposed. The propos...

The detection of covert channels in communication networks is a current security challenge. By clandestinely transferring information, covert channels are able to circumvent security barriers, compromise systems, and facilitate data leakage. A set of statistical methods called DAT (Descriptive Analytics of Traffic) has been previously proposed as a general approach for detecting covert channels...

Within the last years, new techniques for network covert channels arose, such as covert channel overlay networking, protocol switching covert channels, and adaptive covert channels. These techniques have in common that they rely on covert channel-internal control protocols (so called micro protocols) placed within the hidden bits of a covert channel’s payload. An adaptable approach for the engi...

Communication is not necessarily made secure by the use of encryption alone. The mere existence of communication is often enough to raise suspicion and trigger investigative actions. Covert channels aim to hide the very existence of the communication. The huge amount of data and vast number of different protocols in the Internet makes it ideal as a high-bandwidth vehicle for covert communicatio...

Covert motor learning can sometimes transfer to overt behavior. We investigated the neural mechanism underlying transfer by constructing a two-context paradigm. Subjects performed cursor movements either overtly using arm movements, or covertly via a brain-machine interface that moves the cursor based on motor cortical activity (in lieu of arm movement). These tasks helped evaluate whether and ...

We define a probabilistic model for the NRL Pump and using FHP-murφ show experimentally that there exists a probabilistic covert channel whose capacity depends on various NRL Pump parameters (e.g. buffer size, number of samples in the moving average, etc).

The paper concerns available steganographic techniques that can be used for creating covert channels for VoIP (Voice over Internet Protocol) streams. Apart from characterizing existing steganographic methods we provide new insights by presenting two new techniques. The first one is network steganography solution which exploits free/unused protocols’ fields and is known for IP, UDP or TCP protoc...