• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권8호
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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%.

• 한국어학
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• 제62권
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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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• 제13권4호
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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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• 제13권1호
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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.

• 정보보호학회논문지
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• 제29권5호
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• pp.961-971
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• 2019

공유 자원 간섭으로 인해 가상머신 간의 격리가 위반되고 은닉 채널 구현이 가능해서 클라우드 컴퓨팅 환경에서 가상머신 간의 격리는 중요 보안 요소이다. 본 논문에서는 Hyper-V 하이퍼바이저의 구조를 분석하여 가상머신 간의 은닉 채널을 구현한다. Hyper-V는 가상머신 간의 상호 배제를 위해 mutex(mutual exclusion) 기법을 사용한다. Mutex로 인해 가상머신 간의 간섭이 발생하고 은닉 채널 구현이 가능함을 밝힌다. 구조가 복잡한 Hyper-V에 적용가능한 mutex 자원 탐색 방안을 고안하여 은닉 채널을 다수 구현하였다. Mutex 기반 은닉 채널은 하드웨어 의존적이지 않으며, 은닉 채널이 탐지되거나 방어되는 경우 다수의 은닉 채널 중에서 다른 은닉 채널을 이용하면 방어 기법 회피가 가능하다.

• International journal of advanced smart convergence
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• 제10권3호
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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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• 제18권4호
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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.

• 한국정보보호학회:학술대회논문집
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• 한국정보보호학회 2001년도 종합학술발표회논문집
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• pp.340-347
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• 2001

MAC(Mandatory Access Control)이나 MLS(Multi Level Security) 보안정책이 적용된 보안운영체제는 주체와 객체에 보안등급(Security Level)과 영역(Category) 값을 부여하고, 부여된 이들 정보에 의해 객체에 행해지는 주체의 접근을 제한한다. 하지만, 이러한 MAC과 MLS 보안이 적용된 경우라 하더라도 시스템의 보안정책을 위반하며 불법적 정보를 유통하게 하는 경로가 있을 수 있다. 본 논문에서는 불법적 정보의 유통경로가 되고 있는 IPC(Inter Process Communication) 메커니즘과 스토리지에 의한 비밀채널을(Covert Channel) 문제 해결 위해 커널 수준의 설계와 구현을 시도하였다. IPC 메커니즘에 의한 불법적 정보흐름 제거를 위해 IPC 메커니즘에 MLS 보안정책을 적용하였고, 스토리지 비밀채널는 시스템 콜 명세를 분석하여 이를 식별, 감사, 지연처리가 가능토록 하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2024년도 춘계학술발표대회
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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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• 제28권3호
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• pp.647-658
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• 2017

본 연구의 목적은 대학생의 내현적 자기애와 평가염려 완벽주의가 SNS 중독경향성에 미치는 상대적 영향력과 더불어 내현적 자기애가 SNS 중독경향성에 미치는 영향에 대한 평가염려 완벽주의의 매개효과를 살펴보는 것이다. 연구대상은 대학생 415명으로 이들을 대상으로 질문지 조사를 실시하였다. 자료 분석은 SPSS win 21을 사용하였다. 연구 결과는 다음과 같다. 첫째, 대학생의 조절실패 및 일상생활장애, 부정정서의 회피, 가상세계지향성 및 금단을 가장 잘 설명하는 변인은 착취/자기중심성이었으며, 몰입 및 내성을 가장 잘 설명하는 변인은 과민/취약성으로 나타났다. 둘째, 평가 염려 완벽주의는 내현적 자기애와 몰입 및 내성, 가상세계지향성 및 금단 간의 관계를 부분 매개하는 반면, 내현적 자기애와 조절실패 및 일상생활장애, 부정정서의 회피 간의 매개하지 않는 것으로 나타났다.