Covert communication aims to hide the very existence of wireless transmissions in order to guarantee a strong security in wireless networks. In this work, we examine the possibility and achievable performance of covert communication in one-way relay networks. Specifically, the relay is greedy and opportunistically transmits its own information to the destination covertly on top of forwarding th...

Covert channels can be used to circumvent system and network policies by establishing communications that have not been considered in the design of the computing system. We construct a covert channel between different computing systems that utilizes audio modulation/demodulation to exchange data between the computing systems over the air medium. The underlying network stack is based on a commun...

Covert channels may be dangerous to company networks as they can lead to the leakage of confidential information. However, it is hard to assess what bandwidth of a covert channel poses a serious threat. Generally, it depends on the security policy that is implemented by the organisation concerned. The ideal case will be to eliminate all possibilities of hidden communication, but practically it ...

Lost audio packet steganography (LACK) is a steganography technique established on the VoIP network. LACK provides a high-capacity covert channel over VoIP network by artificially delaying and dropping a number of packets in use to convey stegnogram. However, the increasing loss of packets will hurt the quality of the VoIP service. The quality deterioration will not only affect the legitimate V...

We present a protocol for sending data over a common class of low-bandwidth covert channels. Covert channels exist in most communications systems and allow individuals to communicate truly undetectably. However, covert channels are seldom used due to their complexity. Our protocol is both practical and secure against attack by powerful adversaries. We implement our protocol on a standard platfo...

A general framework for exploiting covert channels in combinatorial games is presented. The framework is applicable to all combinatorial games, including Chess and Go, but is applied to the game of Tic-Tac-Toe for ease of experimental analysis. The security and capacity of the resulting covert channel are analyzed experimentally. By considering the ways in which a passive adversary can attempt ...

Previous research has demonstrated categorical perception (CP) of facial expressions from American Sign Language (ASL) in hearing, English-speaking non-signers. Notably, CP was observed even for faces with no obvious linguistic labels in English, suggesting the existence of covert categories based on nonlinguistic facial properties. However, in the earlier work, CP was assessed using memory pro...

In this paper, we evaluate available steganographic techniques for SIP (Session Initiation Protocol) that can be used for creating covert channels during signaling phase of VoIP (Voice over IP) call. Apart from characterizing existing steganographic methods we provide new insights by introducing new techniques. We also estimate amount of data that can be transferred in signalling messages for t...

With the increasing growth of electronic communications, it is becoming important to provide a mechanism for enforcing various security policies on network communications. This paper discusses our implementation of several previously proposed protocols that enforce the Bell LaPadula security model. We also introduce a new protocol called \Quantized Pump" that ooers several advantages, and prese...