• Journal of Positioning, Navigation, and Timing
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• v.13 no.4
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• pp.409-423
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• 2024

Satellite navigation systems provide services such as positioning, navigation, and timing (PNT), by transmitting navigation messages through signals. However, there is possibility that the signals can be spoofed and fake PNT information can be transmitted to the receiver. To prevent spoofing attacks, navigation messages should be authenticated. Although the Japanese Quasi-Zenith Satellite System (QZSS) recently adopted authentication services for L1C/A, L1C, and L5, it does not yet provide authentication services for its Centimeter Level Augmentation Service (CLAS). To adopt authentication functionality for the existing CLAS that already has its own message structure, only reserved fields can be used for authentication. In this study, we propose two compact navigation message authentication protocols using reserved fields of QZSS CLAS message. They are based on the Elliptic Curve Digital Signature Algorithm (ECDSA) and Timed Efficient Stream Loss-tolerant Authentication (TESLA), which have been widely considered for other signal authentication services such as GPS Chimera and Galileo Open Service Navigation Message Authentication (OSNMA). According to our experiments, the proposed ECDSA-only method needs 6 to 12 min for authentication and the proposed ECDSA-TESLA method requires 4 to 6 min.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.10
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• pp.724-739
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• 2009

This paper suggests the energy-efficient message delivery scheme and the software platform which exploits the multiple network interfaces of the mobile terminals and GPS in the current mobile devices. The mobile terminals determine the delivery method among 'direct', 'indirect', and 'WAN' based on the position information of itself and other terminals. 'Direct' method sends a message directly to the target terminal using local RAT. 'Indirect' method extends the service area by exploiting intermediate terminals as relay node. If the target terminal is too far to reach through 'direct' or 'indirect' method, the message is sent using wireless WAN technology. Our proposed scheme exploits the position information and, thus, power consumption is drastically reduced in determining handover time and direction. Network simulation results show that our proposed delivery scheme improves the message transfer efficiency and the handover detection latency. We implemented a message platform in a smart phone realizing the proposed delivery scheme. We compared our platform with other typical message platforms from energy efficiency aspect by observing the real power consumption and applying the mathematical modeling. The comparison results show that our platform requires significantly less power.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.1
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• pp.81-88
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• 2013

As social network service(SNS) has grown rapidly, the variety information being shared through SNS. However, the privacy of individuals can be violated due to the shared information through a SNS or the post written in the past at the SNS. Although, many researches concerned about it, they did not suggest key management and access control especially. In this paper, we propose the method for the protection of the message in SNS using access control and hash-chain.

• Journal of the Korea Computer Industry Society
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• v.9 no.3
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• pp.121-128
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• 2008

This paper suggested a location-based traffic information service system using TPEG and GIS. Measurement technique, location server, applied service technique, and linkage technique with database were used to provide the location-based traffic information service. In particular, TPEG-RTM includes location information and load traffic message. The location information to be included in each message displayed a specific point, section or region limit of the load. Actually, because it was impossible to receive data using TPEG receiver, a proposed program included in this paper was used to produce an arbitrary database and read it, Also, TPEG event happened time was indicated on the map for matching test of a TPEG message and WGS84 coordinate, and finally it was verified with art example of a vehicle approaching to an event happened place.

• Journal of the Semiconductor & Display Technology
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• v.23 no.3
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• pp.115-120
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• 2024

As smartphones become more integral to daily life, security concerns, particularly regarding smishing, have risen significantly. With the increasing frequency and variety of smishing attacks, current detection methods struggle to provide effective solutions, with most commercial algorithms achieving around a 70% detection rate. This paper proposes a novel approach to enhancing smishing detection accuracy by utilizing Natural Language Processing to analyze message syntax and semantics, combined with URL Punycode conversion and whitelist techniques. The approach focuses on improving detection through comprehensive message analysis, aiming to address the limitations of existing preventive methods. The proposed system offers conceptual improvements in smishing detection strategies, providing a more robust framework for addressing evolving security challenges.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1215-1223
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• 2014

In multi-hop wireless networks, a message transmission path is set up on demand by a route discovery step, where a shortest path is used in general. The shortest path, however, normally uses the nodes near the center area, which causes a high traffic load in that area and reduces the message transmission reliability. We propose a stable routing protocol considering the remaining energy of nodes. Our protocol uses ETX as a link performance estimator and tries to avoid the nodes with smaller energy. By doing this, we can reduce the route failure probability and packet loss. We have evaluated the performance of the proposed protocol using QualNet and compared with AODV and MRFR protocols. The simulation result shows that our protocol has a similar performance as MRFR in terms of end-to-end message reception ratio, average message delay and delay jitter, but outperforms MRFR in terms of traffic load distribution.

• Journal of Korea Multimedia Society
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• v.8 no.3
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• pp.379-388
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• 2005

Image steganography Is a secret communication scheme to transmit a secret message, which is embedded into an image. The original image and the embedded image are called the cover image and the stego image, respectively. In other words, a sender embeds a secret message into a cover image and transmits a stego image to a receiver, while the receiver takes the stego image, extracts the message from it, and reads the message. General requirements for steganography are great capacity of secret messages, imperceptibility of stego images, and confidentiality between a sender and a receiver. In this paper, we propose a method for being satisfied with three requirements. In order to hide a secret message into a cover image safely, we use a difference value of two consecutive pixels and a secret quantization range. The former is used for the imperceptibility and the latter for the confidentiality. Furthermore, the number of insertion bits is changed according to the difference value for the imperceptibility. Through experiments, we have shown that our method is more good quality of stego images than many other related methods and increases the amount o( message insertion by performing dual insertion processing for some pixels.

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.282-291
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• 2008

This paper focuses on message complexity performance analysis of MANET AAPs in reference to link errors generated by the mobile wireless nodes. To obtain the message complexity performance of AAPs in reference to the link error probability ($P_e$), an enhancement was made by proposing the retransmission limit (S) to be computed for error recovery (based on the link error probability), and then for each of the AAPs the control procedures for the retransmission limit have been properly included. The O-notation has been applied in analyzing the upper bound of the number of messages generated by a MANET group of N nodes. Based on a link error probability range of $P_e=0$ to 0.8, the AAPs investigated in this paper are Strong DAD, Weak DAD with proactive routing protocol (WDP), Weak DAD with on-demand routing protocol (WDO), and MANETconf. Based on the simulation results and analysis of the message complexity, for nominal situations, the message complexity of WDP was lowest, closely followed by WDO. The message complexity of MANETconf is higher than that of WDO, and Strong DAD results to be most complex among the four AAPs.

• Journal of KIISE
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• v.44 no.1
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• pp.13-20
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• 2017

A message processor is server software that receives various message formats from clients, creates the corresponding threads to process them, and lastly delivers the results to the destination. Considering that each function of an SEDA-based message processor has its own characteristics such as CPU-bound or IO-bound, this paper proposes a thread-mapping strategy called "FC-TM" (function-characteristic aware thread mapping) that schedules the threads to the cores based on the function characteristics in multi-core environments. This paper assumes that message-processor functions are static in the sense that they are pre-defined when the message processor is built; therefore, we profile each function in advance and map each thread to a core using the information in order to maximize the throughput. The benchmarking results show that the throughput increased by up to a maximum of 72 % compared with the previous studies when the ratio of the IO-bound functions to the CPU-bound functions exceeds a certain percentage.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.979-985
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• 2016

In this paper, a distributed instant message system with multiple servers architecture which can distribute system load effectively using an extended media control channel has been presented. A media control channel provides establishing a reliable control channel and also keeping a reliable control channel between SIP server and client in the field of real-time media transport area. In this study, a new instant message system architecture which can distribute massive instant message including multimedia data to multiple servers has been presented. The presented instant message system architecture can distribute system load by extending media control channel. For this purpose, media control channel messages, which distribute system load to multiple servers dynamically according to increasing number of users, have been designed in our presented system. And, in our research, an exchanging procedures of media control channel messages between servers have also been presented. The performance of the proposed system has been analysed by simulation.