• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2019년도 춘계학술대회
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• pp.288-289
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• 2019

This paper studies the secrecy capacity for a wireless cooperative network with perfect channel state information at the relays, and receiver. A similar assumption is also made for the instance where there exist a direct link between the transmitter and receiver. Physical Layer security techniques are employed in wireless networks to mitigate against the activity of eavesdroppers. It offers a viable alternative to computationally intensive encryption. In this paper the design of a protocol utilizing jamming (via jamming nodes) for better security and relaying (via relay nodes) for the amplify-and-forward (AF) operation, is investigated. A a signal-to-noise variant of secrecy known as secrecy gap is explored because of its use of lesser computational power - preferable for practical systems. Thus we maximize this signal-to-noise approach instead of the conventional secrecy capacity maximization method. With this, an iterative algorithm using geometric programming (GP) and semi-definite programming (SDP) is presented with appreciable benefits. The results show here highlight the benefits of using fractional components of the powers of the relays to offer better secrecy capacity.

• 한국인터넷방송통신학회논문지
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• 제14권1호
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• pp.179-187
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• 2014

언더레이 프로토콜은 2차 시스템이나 인지된 사용자가 1차 사용자의 품질 저하 없이 동일한 주파수를 사용하는 인지 기술이다. 또한, 무선 환경의 중계 특성으로 인해, 몇몇 노드는 도청 노드라고 불리며, 다른 통신 링크를 위한 정보를 수신한다. 이러한 이유로, 물리 계층의 보안은 도청의 발생을 막기 위해 보안 성취율을 고려하여 응용된다. 본 논문에서는, 물리 계층 보안과 간섭 제약 환경에서 증폭 후 전송 기법의 성능을 협력 통신 노드를 이용하여 분석한다. 이 모델에서, 중계기는 송신단에서 수신단으로의 신호 전송을 돕기 위해 증폭 후 전송 기법을 사용한다. 우수한 중계기는 기회주의적 중계기 선택 기법으로 선정되며, 단 대 단 보안 성취율을 기초로 한다. 시스템 성능은 보안 성취율의 정전 확률로 평가된다. 정전 확률의 상향, 하향 한계는 국제 통계 채널 상태 정보(CSI)에 기초하며, 또한, 닫힌계로 유도한다. 시뮬레이션 결과는 인지 네트워크는 1차 사용자로부터 충분히 멀 때, 중계기에서 도청 노드까지의 거리가 중계기에서 수신단까지의 거리보다 큰 경우 시스템 성능이 향상된 것을 보여준다.

• International Journal of Computer Science & Network Security
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• 제21권3호
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• pp.48-54
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• 2021

Security is an important issue for wireless communications and poses many challenges. Most security schemes have been applied to the upper layers of communications networks. Since in a typical wireless communication, transmission of data is over the air, third party receiver(s) may have easy access to the transmitted data. This work examines a new security technique at the physical layer for the sake of enhancing the protection of wireless communications against eavesdroppers. We examine the issue of secret communication through Rayleigh fading channel in the presence of an eavesdropper in which the transmitter knows the channel state information of both the main and eavesdropper channel. Then, we analyze the capacity of the main channel and eavesdropper channel we also analyze for the symbol error rate of the main channel, and the outage probability is obtained for the main transmission. This work elucidate that the proposed security technique can safely complement other Security approaches implemented in the upper layers of the communication network. Lastly, we implement the results in Mat lab

• Journal of Communications and Networks
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• 제11권6호
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• pp.544-555
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• 2009

This work continues a trend of developments aimed at exploiting the physical layer of the open systems interconnection (OSI) model to enhance wireless network security. The goal is to augment activity occurring across other OSI layers and provide improved safeguards against unauthorized access. Relative to intrusion detection and anti-spoofing, this paper provides details for a proof-of-concept investigation involving "air monitor" applications where physical equipment constraints are not overly restrictive. In this case, RF fingerprinting is emerging as a viable security measure for providing device-specific identification (manufacturer, model, and/or serial number). RF fingerprint features can be extracted from various regions of collected bursts, the detection of which has been extensively researched. Given reliable burst detection, the near-term challenge is to find robust fingerprint features to improve device distinguishability. This is addressed here using wavelet domain (WD) RF fingerprinting based on dual-tree complex wavelet transform (DT-$\mathbb{C}WT$) features extracted from the non-transient preamble response of OFDM-based 802.11a signals. Intra-manufacturer classification performance is evaluated using four like-model Cisco devices with dissimilar serial numbers. WD fingerprinting effectiveness is demonstrated using Fisher-based multiple discriminant analysis (MDA) with maximum likelihood (ML) classification. The effects of varying channel SNR, burst detection error and dissimilar SNRs for MDA/ML training and classification are considered. Relative to time domain (TD) RF fingerprinting, WD fingerprinting with DT-$\mathbb{C}WT$ features emerged as the superior alternative for all scenarios at SNRs below 20 dB while achieving performance gains of up to 8 dB at 80% classification accuracy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3414-3434
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• 2016

Classical key generation is complicated to update and key distribution generally requires fixed infrastructures. In order to eliminate these restrictions researchers have focused much attention on physical-layer (PHY-layer) based key generation methods. In this paper, we present a PHY-layer fingerprints based fuzzy key generation scheme, which works to prevent primary user emulation (PUE) attacks and spectrum sensing data falsification (SSDF) attacks, with multi-node collaborative defense strategies. We also propose two algorithms, the EA algorithm and the TA algorithm, to defend against eavesdropping attacks and tampering attacks in mobile cognitive radio networks (CRNs). We give security analyses of these algorithms in both the spatial and temporal domains, and prove the upper bound of the entropy loss in theory. We present a simulation result based on a MIMO-OFDM communication system which shows that the channel response characteristics received by legitimates tend to be consistent and phase characteristics are much more robust for key generation in mobile CRNs. In addition, NIST statistical tests show that the generated key in our proposed approach is secure and reliable.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2017년도 추계학술발표대회
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• pp.207-210
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• 2017

가시광 통신 환경 내에서 사용자가 데이터를 받을 때, 공격자가 도청하는 위치는 특정할 수 없다. 공격자는 특정되지 않은 위치에서 다양한 행위를 할 수 있다. 공격자는 조명 그 자체를 관측하여 유의미한 데이터를 얻을 수도 있고, 사용자의 근처에서 사용자와 같은 데이터를 얻을 수도 있다. 이와 같은 도청 행위를 방지하기 위해서 암호화가 필요하다. 본 연구에서는 사용자의 통신에 지장을 주지 않는 물리계층 암호화 방법을 제안한다.

• Journal of Communications and Networks
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• 제11권6호
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• pp.634-644
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• 2009

A diversity of wireless networks, with rapidly evolving wireless technology, are currently in service. Due to their innate physical layer vulnerability, wireless networks require enhanced security components. WLAN, WiBro, and UMTS have defined proper security components that meet standard security requirements. Extensive research has been conducted to enhance the security of individual wireless platforms, and we now have meaningful results at hand. However, with the advent of ubiquitous service, new horizontal platform service models with vertical crosslayer security are expected to be proposed. Research on synchronized security service and interoperability in a heterogeneous environment must be conducted. In heterogeneous environments, to design the balanced security components, quantitative evaluation model of security policy in wireless networks is required. To design appropriate evaluation method of security policies in heterogeneous wireless networks, we formalize the security properties in wireless networks. As the benefit of security protocols is indicated by the quality of protection (QoP), we improve the QoP model and evaluate hybrid security policy in heterogeneous wireless networks by applying to the QoP model. Deriving relative indicators from the positive impact of security points, and using these indicators to quantify a total reward function, this paper will help to assure the appropriate benchmark for combined security components in wireless networks.

• ETRI Journal
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• 제42권1호
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• pp.138-149
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• 2020

In this paper, we describe a simultaneously transmitted jamming (ST-jamming) for bi-directional in-band full-duplex (IFD) system to improve information security at the physical layer. By exploiting ST-jamming, each legitimate user transmits data samples and jamming samples together in one orthogonal frequency division multiplexing symbol according to given traffic asymmetry. Regardless of the traffic difference in both directions in IFD communication, eavesdropping of confidential information is prevented in both directions simultaneously without the loss of data rate. We first propose an encoding scheme and the corresponding decoding scheme for ST-jamming to be used by the legitimate users. In addition, we study a transceiver structure of the legitimate users including a baseband modem uniquely designed for the use of ST-jamming. The leakage of confidential information at an eavesdropper is then quantified by studying the mutual information between the confidential transmit signals and the received signals of the eavesdropper. Simulation results show that the proposed ST-jamming significantly reduces the leakage of legitimate information at the eavesdropper.

• 한국인터넷방송통신학회논문지
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• 제14권6호
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• pp.63-67
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• 2014

협력 재밍 기술에 기반한 분산 제로 빔포밍은 도청자가 시드 공유를 감지 할 수 없으며, 도청자가 도청하기 위해 송신단 주변에 위치한 경우 기존의 기법은 제한적으로 적용된다. 따라서 본 논문에서는 이러한 특수한 시나리오에 대한 해결책을 제시한다. 첫 번째 시간 슬롯에서 중계기는 이진 재밍 메시지를 무작위로 생성하고 송신단과 수신단으로 전송한다. 두 수신기가 안전하고 정확하게 메시지를 복호할 때, 송신단은 정보 메시지와 복호된 메시지에 대한 배타적 논리합 기법을 기반으로 다른 메시지를 만들고 전송하게 되며 도청 노드에 의한 도청을 방지할 수 있다. 마지막으로 본 프로토콜을 기존의 기법과 비교하여 성능을 분석하였으며 도청 노드의 위치에 따른 결과가 우수함을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권11호
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• pp.4623-4643
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• 2015

This paper considers physical-layer security protocols in multicast cognitive radio (CR) networks. In particular, we propose dual-hop cooperative decode-and-forward (DF) and randomize-and-forward (RF) schemes using partial relay selection method to enhance secrecy performance for secondary networks. In the DF protocol, the secondary relay would use same codebook with the secondary source to forward the source's signals to the secondary destination. Hence, the secondary eavesdropper can employ either maximal-ratio combining (MRC) or selection combining (SC) to combine signals received from the source and the selected relay. In RF protocol, different codebooks are used by the source and the relay to forward the source message secretly. For each scheme, we derive exact and asymptotic closed-form expressions of secrecy outage probability (SOP), non-zero secrecy capacity probability (NzSCP) in both independent and identically distributed (i.i.d.) and independent but non-identically distributed (i.n.i.d.) networks. Moreover, we also give a unified formula in an integral form for average secrecy capacity (ASC). Finally, our derivations are then validated by Monte-Carlo simulations.