• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.8
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• pp.3550-3566
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• 2020

As a widely used way to exfiltrate information, wireless covert channel (WCC) brings a serious threat to communication security, which enables the wireless communication process to bypass the authorized access control mechanism to disclose information. Unlike the covert channel on the network layer, wireless covert channels on the physical layer (WCC-P) is a new covert communication mode to implement and improve covert wireless communication. Existing WCC-P scheme modulates the secret message bits into the Gaussian noise, which is also called covert digital communication system based on the joint normal distribution (CJND). Finding the existence of this type of covert channel remains a challenging work due to its high undetectability. In this paper, we exploit the square autocorrelation coefficient (SAC) characteristic of the CJND signal to distinguish the covert communication from legitimate communication. We study the sharp increase of the SAC value when the offset is equal to the symbol length, which is caused by embedding secret information. Then, the SAC value of the measured sample is compared with the threshold value to determine whether the measured sample is CJND sample. When the signal-to-noise ratio reaches 20db, the detection accuracy can reach more than 90%.

• Korean Linguistics
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• v.62
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• pp.223-261
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• 2014

From the perspective of cross-cultural communication, it can be easily assumed that non-natives may have great difficulty understanding names of Korean dishes with covert information considering that even understanding those with overt information is a demanding task for them. Complex issues raised by cultural and linguistic differences hinder non-natives from having a clear understanding on names of Korean dishes. In order to resolve this problem, this paper focuses on providing clues to overcoming obstacles of cross-cultural communication in understanding names of Korean dishes by presenting issues including following cases:1. Analysis on types of Korean dish names with covert information in comparison to dish names with overt information. 2. Names of dishes made with a single contain covert information regarding a specific cooking and processing method. 3. A particular aspect regarding Korean food culture is that morphemes with a meaning of meat or flesh('gogi', 'sal', 'yook') contained in dish names indicate covert information that the dish is made of 'beef'.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.4
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• pp.1866-1883
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• 2019

As the youngest branch of information hiding, network covert timing channels conceal the existence of secret messages by manipulating the timing information of the overt traffic. The popular model-based framework for constructing covert timing channels always utilizes cumulative distribution function (CDF) of the inter-packet delays (IPDs) to modulate secret messages, whereas discards high-order statistics of the IPDs completely. The consequence is the vulnerability to high-order statistical tests, e.g., entropy test. In this study, a rich security model of covert timing channels is established based on IPD chains, which can be used to measure the distortion of multi-order timing statistics of a covert timing channel. To achieve rich security, we propose two types of covert timing channels based on nested lattices. The CDF of the IPDs is used to construct dot-lattice and interval-lattice for quantization, which can ensure the cell density of the lattice consistent with the joint distribution of the IPDs. Furthermore, compensative quantization and guard band strategy are employed to eliminate the regularity and enhance the robustness, respectively. Experimental results on real traffic show that the proposed schemes are rich-secure, and robust to channel interference, whereas some state-of-the-art covert timing channels cannot evade detection under the rich security model.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.243-248
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• 2021

Although many different types of covert channels have been suggested in the literature, there are little work in directly applying game theory to building up covert channel. This is because researchers have mainly focused on tailoring game theory for covert channel analysis, identification, and covert channel problem solving. Unlike typical adaptation of game theory to covert channel, we show that game theory can be utilized to establish a new type of covert channel in IoT devices. More specifically, we propose a covert channel that can be constructed by utilizing the Nash Equilibrium with sensor data collected from IoT devices. For covert channel construction, we set random seed to the value of sensor data and make payoff from random number created by running pseudo random number generator with the configured random seed. We generate I × J (I ≥ 2, J ≥ 2) matrix game with these generated payoffs and attempt to obtain the Nash Equilibrium. Covert channel construction method is distinctly determined in accordance with whether or not to acquire the Nash Equilibrium.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.5
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• pp.961-971
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• 2019

Isolation between virtual machines in a cloud computing environment is an important security factor. The violation of isolation between virtual machines leads to interferences of shared resources and the implementation of covert channels. In this paper, the structure of Hyper-V hypervisor is analyzed to implement covert channels between virtual machines. Hyper-V uses a mutex technique for mutual exclusion between virtual machines. It indicates that isolation of virtual machines is violated and covert channels can be implemented due to mutex. We implemented several covert channels by designing a method for searching mutex resources applicable to Hyper-V with complex architectures. The mutex-based covert channel is not hardware dependent. If the covert channel is detected or defended, the defensive technique can be avoided by using the other covert channel among several covert channels.

• International journal of advanced smart convergence
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• v.10 no.3
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• pp.10-16
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• 2021

In this paper, we devise a Shapley-value-based covert channel in smartphones. More specifically, unlike ordinary use of Shapley value in cooperative game, we make use of a series of Shapley values, which are computed from sensor data collected from smartphones, in order to create a covert channel between encoding smartphone and decoding smartphone. To the best of our knowledge, we are the first to contrive covert channel based on Shapley values. We evaluate the encoding process of our proposed covert channel through simulation and present our evaluation results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.4
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• pp.1020-1041
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• 2024

With the development of covert communication technologies, the number of covert communication technologies using blockchain as a carrier is increasing. However, using the transaction amount of digital currency as a carrier for covert communication has problems such as low embedding rate, large consumption of transaction amount, and easy detection. In this paper, firstly, by experimentally analyzing the distribution of bitcoin transaction amounts, we determine the most suitable range of amounts for matrix decomposition. Secondly, we design a novel matrix decomposition method that can successfully decompose a large amount matrix into two small amount matrices and utilize the elements in the small amount matrices for covert communication. Finally, we analyze the feasibility of the novel matrix decomposition method in this scheme in detail from four aspects, and verify it by experimental comparison, which proves that our scheme not only improves the embedding rate and reduces the consumption of transaction amount, but also has a certain degree of resistance to detection.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2001.11a
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• pp.340-347
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• 2001

Security operating system applied to MAC(Mandatory Access Control) or to MLS(Multi Level Security) gives both subject and object both Security Level and value of Category, and it restrict access to object from subject. But it violates Security policy of system and could be a circulated course of illegal information. This is correctly IPC(Interprocess Communication)mechanism and Covert Channel. In this thesis, I tried to design and implementation as OS kernel in order not only to give confidence of information circulation in the Security system, but also to defend from Covert Channel by Storage and IPC mechanism used as a circulated course of illegal information. For removing a illegal information flow by IPC mechanism. I applied IPC mechanism to MLS Security policy, and I made Storage Covert Channel analyze system call Spec. and than distinguish Storage Covert Channel. By appling auditing and delaying, I dealt with making low bandwidth.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.395-396
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• 2024

최근 국가 핵심 기반시설을 중단시키거나 파괴시킴으로서 사회적 혼란 및 국가 경제적 손실을 일으키는 공격 사례가 증가되고 있는 실정이다. 이와 같은 사이버 공격에 대응하기 위해 각 국가는 인터넷이나 다른 네트워크와 물리적 또는 논리적으로 분리되어 있는 폐쇄망 환경을 기반으로 기반시설을 구성함으로서 높은 수준의 보안성과 안정성을 유지하고자 한다. 하지만, 악의적인 공격자들은 Covert Channel을 통해 폐쇄망 환경 내 민감한 데이터 및 기밀 데이터를 탈취하고 있는 실정이다. 이에 본 논문에서는 음향신호 기반 Covert Channel 공격 기술에 대해 분석함으로써 안전한 폐쇄망 환경 구축의 필요성을 보이고자 한다.

• Journal of the Korean Data and Information Science Society
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• v.28 no.3
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• pp.647-658
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• 2017

This study aims to explore the relative influences of covert narcissism and evaluative concerns perfectionism on SNS addiction tendency, and the mediating effect of evaluative concerns perfectionism in the influence of covert narcissism on SNS addiction tendency of undergraduates. The results of this study can be summarized in the following. First, control failure and disturbance of adaptive, avoidance of negative emotion, and virtual life orientation and withdrawal were best accounted for by exploitation/self-centeredness. On the other hand, absorption and tolerance was best accounted for by hypersensitivity/vulnerability in undergraduates. Also, SNS addiction tendency was accounted for by only socially prescribed perfectionism of evaluative concerns perfectionism. Second, evaluative concerns perfectionism partially mediated the relations between covert narcissism and absorption and tolerance and between covert narcissism and virtual life orientation and withdrawal, while it didn't mediate the relations between covert narcissism and control failure and disturbance of adaptive and between covert narcissism and avoidance of negative emotion.