• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.747-754
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• 2016

DHCP(Dynamic Host Configuration Protocol) is a protocol for efficiency and convenience of the IP address management. DHCP automatically assigns an IP address and configuration information needed to run the TCP/IP communication to individual host in the network. However, existing DHCP is vulnerable for network attack such as DHCP spoofing, release attack because there is no mutual authentication systems between server and client. To solve this problem, we have designed a new DHCP protocol supporting the following features: First, ECDH(Elliptic Curve Diffie-Hellman) is used to create session key and ECDSA(Elliptic Curve Digital Signature Algorithm) is used for mutual authentication between server and client. Also this protocol ensures integrity of message by adding a HMAC(Hash-based Message Authentication Code) on the message. And replay attacks can be prevented by using a Nonce. As a result, The receiver can prevent the network attack by discarding the received message from unauthorized host.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.6 s.348
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• pp.23-29
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• 2006

It is difficult to apply conventional security algorithms to the wireless sensor networks composed of nodes that have resource constraints such as memory, computing, power resources limitation. Generally, shared key based algorithms with low resource consumption and short key length are used for broadcast packets in authentication of base station. But it is not suitable that all the nodes hold the same shared key only for packet authentication. Recently, broadcast authentication algorithm for sensor network is proposed, which uses key chain generation by one-way hash function, Message Authentication Code generation by each keys of the key chains and delayed key disclosure. It provides suitable authentication method for wireless sensor networks but may leads to inefficient consequence with respect to network conditions such as broadcast ratio, key chain level, and so on. In this paper, we propose an improved broadcast authentication algorithm that uses key chain link and periodical key disclosure. We evaluated the performance of proposed algorithm using TOSSIM(TinyOS Simulator) in TinyOS. The results show that the proposed algorithm ensures low authentication delay, uses memory and computing resource of receiving nodes efficiently and reduces the amount of packet transmitting/receiving.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.729-738
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• 2019

In this paper, we propose two-way authentication protocol between unmanned systems in tactical wireless networks in which long distance communications are not guaranteed due to a poor channel conditions. It is assumed that every unmanned systems have same random data set before they put into combat. The proposed protocol generates authentication code(AC) using random data that causes hash collision. The requester for authentication encrypts the materials such as their identifier, time-stamp, authentication code with the secret key. After then the requester transmits the encrypted message to the receiver. The receiver authenticates the requester by verifying the authentication code included in the request message. The performance analysis of the proposed protocol shows that it guarantees the security for various attack scenarios and efficiency in terms of communication overhead and computational cost. Furthermore, we analyzed the effect of the parameter values of the proposed protocol on the performance and suggest appropriate parameter value selection guide according to the level of security requirement.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.2
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• pp.43-50
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• 2020

In this paper a low power Spreading Code Authentication (SCA) sequence with a BPSK(1) modulation at a frequency offset of +7.161 MHz is tested for authentication purposes, the Galileo E1OS is used as base signal. The tested signals comprise a Galileo constellation with 5 satellites including the Galileo OS Navigation Message Authentication (OSNMA) and a low power offset BPSK (OBPSK(7,1)) as SCA component. The signals are generated with the software based MuSNAT-Signal-Generator. The generated signals were transmitted Over-The-Air (OTA) using a Software-Defined-Radio (SDR) as pseudolite. With a real-environment-testbed the performance of the SCA in real channel conditions (fading and multipath) was tested. A new SCA evaluation scheme is proposed and was implemented. Under real channel conditions we derive experimental threshold values for the new SCA evaluation scheme which allow a robust authentication. A Security Code Estimation and Replay (SCER) spoofing attack was mimicked on the real-environment-testbed and analyzed with the SCA evaluation scheme. It was shown that the usage of an OBPSK is feasible as an authentication method and can be used in combination with the OSNMA to improve the authentication robustness against Security SCER attacks.

• Journal of KIISE
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• v.43 no.11
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• pp.1245-1258
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• 2016

Cryptographic technologies providing confidentiality and integrity such as encryption algorithms and message authentication codes (MACs) are necessary for preventing security threats in the Internet of Things (IoT) where various kinds of devices are interconnected. As a number of encryption schemes that have passed security verification are not necessarily suitable for low-power and low-performance IoT devices, various lightweight cryptographic schemes have been proposed. However, a study of lightweight MACs is not sufficient in comparison to that of lightweight block ciphers. Therefore, in this paper, we reviewed various kinds of MACs for their classification and analysis and then, we presented a new way for future MAC development. We also implemented major MAC algorithms and performed experiments to investigate their performance degradation on low-end micro-controllers.

• Review of KIISC
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• v.3 no.4
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• pp.27-37
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• 1993

본 연구에서는 기존의 메세지 인증방식인 MAC(Message Aunthentication Code)와 MDC(Manipulation Detection Code)에 대한 제 3자의 적극적인 공격(active attack)하에서의 구조직인 취약점을 분석하고, 이를 보완하는 새로운 인증 방식을 제안하고 검증하였다. 새로운 메세지 인증방식은 기존의 방식과는 다르레 제3자의 공격을 받은 메세지 블럭을 바로 검출할 수 있다는 장점을 가지고 있기 때문에 통신 시스템 상에서 불필요한 메세지의 재전송을 줄일 수 있다는 측면에서 효율적인 인증 방식이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2B
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• pp.162-169
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• 2009

Message Authentication Code (MAC) assures integrity of messages. In Mobile WiMAX, 128-bit Cipher-based MAC (CMAC) is calculated for management messages but only the least significant half is actually used truncating the most significant 64 bits. Naming these unused most significant 64bits Shared Authentication Information (SAI), we suggest that SAI can be applied to protect the network from DDoS attack which exploits idle mode vulnerabilities. Since SAI is the unused half of CMAC, it is as secure as 64bits of CMAC and no additional calculations are needed to obtain it. Moreover, SAI doesn't have to be exchanged through air interface and shared only among MS, BS, and ASN Gateway. With these good properties, SAI can efficiently reduce the overheads of BS and ASN GW under the DDoS attack.

• The Journal of Korean Association of Computer Education
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• v.10 no.3
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• pp.57-66
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• 2007

E-mail system is considered as a most important communication media, which can be used to transmit personal information by internet. But e-mail attack also has been increased by spoofing e-mail sender address. Therefore, this work proposes sender verification faculty for spam mail protection at sender's MTA by using security card for protection forged sender and also for authenticating legal sender. Sender's mail MT A requests security card's code number to sender. Then sender input code number and generate session key after sender verification. Session key is used to encrypt sender's signature and secure message transmission. This work can provide efficient and secure e-mail sender authentication with sender verification and message encryption.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1519-1527
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• 2007

In order to combat the security threats that sensor networks are exposed to, a cryptography protocol is implemented at sensor nodes for point-to-point encryption between nodes. Given that nodes have limited resources, symmetric cryptography that is proven to be efficient for low power devices is implemented. Data protection is integrated into a sensor's packet by the means of symmetric encryption with the Dragon stream cipher and incorporating the newly designed Dragon-MAC Message Authentication Code. The proposed algorithm was designed to employ some of the data already computed by the underlying Dragon stream cipher for the purpose of minimizing the computational cost of the operations required by the MAC algorithm. In view that Dragon is a word based stream cipher with a fast key stream generation, it is very suitable for a constrained environment. Our protocol regarded the entity authentication and message authentication through the implementation of authenticated encryption scheme in wireless sensor nodes.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.39-47
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• 2005

This paper proposes and analyzes the MAC(Message Authentication Code) algorithm that is used for the transition integrity and the entity authentication of message. The MAC algorithm uses the DES algorithm which has 64-bit block and 56-bit key and we compare the security according to 64-bit and 32-bit length of MAC value. Moreover, we use the SEED algorithm which has 128-bit block and 128-bit key and compare the security according to 128-bit and 64-bit length of MAC value. We analyze the security the forgery attack according to length of message and length of MAC value. this paper, a coarse-to-fine optical flow detection method is proposed. Provided that optical flow gives reliable approximation to two-dimensional image motion, it can be used to recover the three-dimensional motion. but usually to get the reliable optical flows are difficult. The proposed algorithm uses Horn's algorithm (or detecting initial optical flow, then Thin Plate Spline is introduced to warp a image frame of the initial optical flow to the next image frame. The optical flow for the warped image frame is again used iteratively until the mean square error between two image sequence frames is lowered. The proposed method is experimented for the real moving Picture image sequence. The proposed algorithm gives dense optical flow vectors.