• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.2131-2138
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• 2011

GPS is vulnerable to jamming because of extremely low signal power. Many anti-jamming techniques are studied for complement this vulnerability. Anti-jamming techniques using array antenna are most effective technique and these techniques are required the DOA estimates. MUSIC algorithm and Root-MUSIC Algorithm are typical algorithms used in DOA estimation. Two algorithms have different characteristics, so the choice of an algorithm may depends on many factors such as the environment and the system requirements. The analysis and performance comparison of both algorithms is necessary to choose the best method to apply. This paper summarizes the theory of MUSIC and Root-MUSIC algorithms. And this paper extends both algorithm to estimate two-dimensional angles. The software simulator of both algorithms are implemented to evaluate the performance. Root-MUSIC algorithm has the computational advantage on ULA. MUSIC algorithm is applicable to any antenna array. MUSIC shows better estimation performance when number of array element is small while the computational load of MUSIC is much higher than Root-MUSIC.

• ETRI Journal
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• v.41 no.5
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• pp.585-598
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• 2019

A cyber-physical system (CPS) is a new mechanism controlled or monitored by computer algorithms that intertwine physical and software components. Advanced persistent threats (APTs) represent stealthy, powerful, and well-funded attacks against CPSs; they integrate physical processes and have recently become an active research area. Existing offensive and defensive processes for APTs in CPSs are usually modeled by incomplete information game theory. However, honeypots, which are effective security vulnerability defense mechanisms, have not been widely adopted or modeled for defense against APT attacks in CPSs. In this study, a honeypot game-theoretical model considering both low- and high-interaction modes is used to investigate the offensive and defensive interactions, so that defensive strategies against APTs can be optimized. In this model, human analysis and honeypot allocation costs are introduced as limited resources. We prove the existence of Bayesian Nash equilibrium strategies and obtain the optimal defensive strategy under limited resources. Finally, numerical simulations demonstrate that the proposed method is effective in obtaining the optimal defensive effect.

• Journal of the Korea Society of Computer and Information
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• v.24 no.8
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• pp.59-66
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• 2019

As the monetary value of cryptocurrency increases, the security measures for cryptocurrency becomes more important. A limitation of the existing cryptocurrency exchanges is their vulnerability to threats of hacking due to their centralized manner of management. In order to overcome such limitation, blockchain technology is increasingly adopted. The blockchain technology enables decentralization and Peer-to-Peer(P2P) transactions, in which blocks of information are linked in chain topology, and each node participating in the blockchain shares a distributed ledger. In this paper, we propose and implement a mobile electronic wallet that can safely store, send and receive cryptocurrencies. The proposed mobile cryptocurrency wallet connects to the network only when the wallet actively is used. Wallet owner manages his or her private key offline, which is advantageous in terms of security. JavaScript based wallet apps were implemented to respectively run on Android and iOS mobile phones. I demonstrate the process of transferring Ethereum cryptocurrency from an account to another account through Ropsten, a test net for Ethereum. Hardware wallets, such as Ledger Nano S, provide a slightly higher level of security, yet have the disadvantages of added burden of carrying additional physical devices and high costs (about 80$).

• Journal of the Korea Society of Computer and Information
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• v.23 no.12
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• pp.95-105
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• 2018

As the IT industry developed, the information held by the company soon became a corporate asset. As this information has value as an asset, the number and scale of various cyber attacks which targeting enterprises and institutions is increasing day by day. Therefore, research are being carried out to protect the assets from cyber attacks by using the attack graph to identify the possibility and risk of various attacks in advance and prepare countermeasures against the attacks. In the attack graph, security metric is used as a measure for determining the importance of each asset or the risk of an attack. This is a key element of the attack graph used as a criterion for determining which assets should be protected first or which attack path should be removed first. In this survey, we research trends of various security metrics used in attack graphs and classify the research according to application viewpoints, use of CVSS(Common Vulnerability Scoring System), and detail metrics. Furthermore, we discussed how to graft the latest security technologies, such as MTD(Moving Target Defense) or SDN(Software Defined Network), onto the attack graphs.

• Convergence Security Journal
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• v.18 no.4
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• pp.11-17
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• 2018

Hardware Keyloggers are available in a variety of modular keylogger products with small size and Wi-Fi communication capabilities that can be concealed inside the keyboard. Such keyloggers are more likely to leak important information and sensitive information from government, military, business and individuals because they are difficult to detect if they are used by a third party for malicious purposes. However, unlike software keyloggers, research on security solutions and detection methods are relatively small in number. This paper, we investigate security vulnerability caused by hardware keylogger and existing detection methods, and improve the detection possibility of modular hardware keylogger through non-destructive measurement methods, such as power consumption of keyboard, infrared temperature, and X-ray. Furthenmore, We propose a method that can be done with experimental results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.978-1002
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• 2019

With the rapid development of the Internet of Things, the problem of privacy protection has been paid great attention. Recently, Nikooghadam et al. pointed out that Kumari et al.'s protocol can neither resist off-line guessing attack nor preserve user anonymity. Moreover, the authors also proposed an authentication supportive session initial protocol, claiming to resist various vulnerability attacks. Unfortunately, this paper proves that the authentication protocols of Kumari et al. and Nikooghadam et al. have neither the ability to preserve perfect forward secrecy nor the ability to resist key-compromise impersonation attack. In order to remedy such flaws in their protocols, we design a lightweight authentication protocol using elliptic curve cryptography. By way of informal security analysis, it is shown that the proposed protocol can both resist a variety of attacks and provide more security. Afterward, it is also proved that the protocol is resistant against active and passive attacks under Dolev-Yao model by means of Burrows-Abadi-Needham logic (BAN-Logic), and fulfills mutual authentication using Automated Validation of Internet Security Protocols and Applications (AVISPA) software. Subsequently, we compare the protocol with the related scheme in terms of computational complexity and security. The comparative analytics witness that the proposed protocol is more suitable for practical application scenarios.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.1
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• pp.103-114
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• 2008

Single Sign-On is an authentication scheme that enables a user to authenticate once and then to access to the resources of multiple software systems without re-authentication. As web services are being integrated into a single groupware, more web sites are adopting for user convenience. However, these Single Sign-On services are very dependent upon the cookies and thus, simple eavesdropping enables attackers to hiject the user's session. Even worse, the attacker who hijacked one session can move to another site through the Single Sign-On. In this paper, we show the vulnerabilities of the top ranked sites regarding this point of view and also propose a way to protect a user's session.

• Structural Engineering and Mechanics
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• v.77 no.4
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• pp.481-493
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• 2021

Low rise masonry structures are relatively inexpensive and easier to construct compared to other types of structures such as steel and reinforced concrete buildings. However, masonry structures are relatively heavier and less ductile and more vulnerable to damages in earthquakes. In this research, a new innovative low-cost seismic isolator using steel rings (SISR) is employed to reduce the seismic vulnerability of masonry structures. FEA of a masonry structure, made of concrete blocks is used to evaluate the effect of the proposed SISR on the seismic response of the structure. Two systems, fixed base and isolated from the base with the proposed SISRs, are considered. Micro-element approach and ABAQUS software are used for structural modeling. The nonlinear structural parameters of the SISRs, extracted from a recent experimental study by the authors, are used in numerical modeling. The masonry structure is studied in two separate modes, fixed base and isolated base with the proposed SISRs, under Erzincan and Imperial Valley-06 earthquakes. The accelerated response at the roof level, as well as the deformation in the masonry walls, are the parameters to assess the effect of the proposed SISRs. The results show a highly improved performance of the masonry structure with the SISRs.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.207-212
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• 2021

A buffer overflow attack is carried out to subvert privileged program functions to gain control of the program and thus control the host. Buffer overflow attacks should be prevented by risk managers by eradicating and detecting them before the software is utilized. While calculating the size, correct variables should be chosen by risk managers in situations where fixed-length buffers are being used to avoid placing excess data that leads to the creation of an overflow. Metamorphism can also be used as it is capable of protecting data by attaining a reasonable resistance level [1]. In addition, risk management teams should ensure they access the latest updates for their application server products that support the internet infrastructure and the recent bug reports [2]. Scanners that can detect buffer overflows' flaws in their custom web applications and server products should be used by risk management teams to scan their websites. This paper presents an experiment of buffer overflow vulnerability and attack. The aims to study of a buffer overflow mechanism, types, and countermeasures. In addition, to comprehend the current detection plus prevention approaches that can be executed to prevent future attacks or mitigate the impacts of similar attacks.

• KNOM Review
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• v.24 no.2
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• pp.48-55
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• 2021

Ethereum is an open software platform based on blockchain technology that enables the construction and distribution of distributed applications. Ethereum uses a fully distributed connection method in which all participating nodes participate in the network with equal authority and rights. Ethereum networks use Kademlia-based node discovery protocols to retrieve and store node information. Ethereum is striving to stabilize the entire network topology by implementing node discovery protocols, but systems for monitoring are insufficient. This paper develops a WireShark dissector that can receive packet information in the Ethereum node discovery process and provides network packet measurement results. It can be used as basic data for the research on network performance improvement and vulnerability by analyzing the Ethereum node discovery process.