• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.6
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• pp.1515-1523
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• 2015

It has been prevalent to be serviced through WLAN(Wireless Local Area Network) as a variety of mobile devices have been introduced. If the number of mobile devices increases rapidly for the network access in a limited range of ESS(Extended Service Set), a lengthy connection delays are induced due to the initial link setup process of the IEEE 802.11i which is WLAN security standard. In this paper, we propose a new initial link setup protocol which can be executed in the ESS area of WLAN.

• Journal of the Korea Computer Industry Society
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• v.2 no.10
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• pp.1269-1284
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• 2001

The Secure Sockets Layer is a protocol for encryption TCP/IP traffic that provides confidentiality, authentication and data integrity. Also the SSL is intended to provide the widely applicable connection-oriented mechanism which is applicable for various application-layer, for Internet client/server communication security. SSL, designed by Netscape is supported by all clients' browsers and server supporting security services. Now the version of SSL is 3.0. The first official TLS vl.0 specification was released by IETF Transport Layer Security working group in January 1999. As the version of SSL has had upgraded, a lot of vulnerabilities were revealed. SSL and TLS generate the private key with parameters exchange method in handshake protocol, a lot of attacks may be caused on this exchange mechanism, also the same thing may be come about in record protocol. In this paper, we analyze SSL protocol, compare the difference between TLS and SSL protocol, and suggest what developers should pay attention to implementation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.71-76
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• 2015

To resolve inefficient content delivery mechanism in conventional internet-based networks, Content-Centric Networks (CCN) has been proposed for wired and wireless networks. One of issues in wireless CCN-based networks is overhead to achieve reliability on content delivery because CCN uses end-to-end two-way handshake with Interest/content packets. In this paper, a novel protocol to reduce overhead and achieve reliability is proposed. The protocol allows Interest packet to request multiple data packets and multiple data packets to be sent in a row without a Interest packets. The protocol is evaluated through the simulations and the performance improvement is proved.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.4
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• pp.593-605
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• 2014

In this paper, we propose the efficient HW/SW co-design method of light-weight cryptography such as HIGHT, PRESENT and PRINTcipher using GEZEL. At first the symmetric cryptographic algorithms were designed using the GEZEL language which is efficiently used for HW/SW co-design. And for the improvement of performance the HW optimization theory such as unfolding, retiming and so forth were adapted to the cryptographic HW module conducted by FSMD. Also, the operation modes of those algorithms were implemented using C language in 8051 microprocessor, it can be compatible to various platforms. For providing reliable communication between HW/SW and preventing the time delay the improved handshake protocol was chosen for enhancing the performance of the connection between HW/SW. The improved protocol can process the communication-core and cryptography-core on the HW in parallel so that the messages can be transmitted to SW after HW operation and received from SW during encryption operation.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.16-27
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• 2006

The wireless transmission medium inherently broadcasts a signal to all neighbor nodes in the transmission range. Existing asynchronous MAC protocols do not provide a concrete solution for reliable broadcast in link layer. This mainly comes from that an omni-directional broadcasting causes to reduce the network performance due to the explosive collisions and contentions. This paper proposes a reliable broadcast protocol in link taller based on directional antennas, named MDB(MAC protocol for Directional Broadcasting). This protocol makes use of DAST(Directional Antennas Statement Table) information and D-MACA(Directional Multiple Access and Collision Avoidance) scheme through 4-way handshake to resolve the many collision problem wit]1 omni-directional antenna. To analyze its performance, MDB protocol is compared with IEEE 802.11 DCF protocol [9] and the protocol 2 of reference [3], in terms of the success rate of broadcast and the collision rate. As a result of performance analysis through simulation, it was confirmed that the collision rate of the MDB protocol is lower than those of IEEE 802.11 and the protocol 2 of reference [3], and that the completion rate of broadcast of MDB protocol is higher than those of IEEE 802.11 and the protocol 2 of reference [3].

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.1
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• pp.42-56
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• 2002

It is possible but not efficient to model and simulate asynchronous microprocessors with the existing HDLs(HARDware Description Languages) such as VHDL or Verilog. The reason it that the description becomes too complex. and also the simulation time becomes too long to explore the design space. Therefore it is necessary to establish a methodology and develop a tool for modeling the handshake protocol of asynchronous microprocessors very easily and simulating it very fast. Under this objective an efficient CAD(Computer Aided Design) tool SLEDS(System Level Event-Driven Simulator) was developed which can evaluate performance of a processor through modeling with a simple description an simulating with event driven engine in the system level. The ultimate goal in the tool SLEDS is to fin the optimal conditions for a system to produce high performance by balancing the delay of each module in the system. Besides SLEDS aims at verifying the design through comparing the expected results with the actual ones by performing the defined behavior.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.6
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• pp.197-208
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• 2023

In the coming future, anyone using the Internet will have more than one NFT. Unlike FT, NFT can specify the owner, and tracking management is easier than FT. Even in the 2022 survey, WPA2 is the most widely used wireless protocol worldwide to date. As it is a protocol that came out in 2006, it is a protocol with various vulnerabilities at this time. In order to use WPA2-EAP or WPA3 (2018), which were released to compensate for the vulnerabilities of WPA2, additional equipment upgrades are required for STA (station) and AP (access point, router), which are connected devices. The use of expensive router equipment solves the security part, but it is economically inefficient to be introduced in Small Office Home Office (SOHO). This paper uses NFT as a means of authentication and uses the existing WPA2 as it is without equipment upgrade, defend crack tools of WPA2 that have been widely used so far and compared to the existing WPA2, it was shown that it was not difficult to actually use them in SOHO.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.118-127
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• 2006

The wireless transmission medium inherently broadcasts a signal to all neighbor nodes in the transmission range. Existing asynchronous MAC protocols do not provide a concrete solution for reliable broadcast in link layer. This mainly comes from that an omnidirectional broadcasting causes to reduce the network performance due to the explosive collisions and contentions. This paper proposes a directional broadcast protocol by using neighborhood information in the link layer based o,1 directional antennas, named MNDB (MAC protocol with Neighborhood for reliable Directional Broadcast). This protocol makes use of neighborhood information and DMACA (Directional Multiple Access and Collision Avoidance) scheme through 4-way handshake to support a reliable directional broadcast. To analyze its performance, MNDB protocol si compared with $RMDB^{[1]}$, the protocol 2 of reference [3], and IEEE 802.11 $protocol^{[9]}$, in terms of the number of collisions, the number of dropped packets, the number of redundant packets, and broadcast delay.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1307-1315
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• 2017

While the PSK mode of the DTLS is the most efficient in terms of the performance, it is not easy to pre-distribute and manage the symmetric key pairs as the number of sensor devices increases. On the other hand, both the RPK and certificate modes offer a convenient key management tool, but they do not guarantee a good computational performance. In this paper, the end-to-end security protocol suitable for the constrained devices is proposed, based on both the ECQV certificate and the PSK mode. Namely, the initial DTLS handshake is performed using the ECQV certificate, and the subsequent DTLS handshakes with the other CoAP servers in the same group are performed using the PSK mode for the purpose of reducing the overall computational load. Furthermore, a fine-grained access control for the CoAP client can be enforced to allow access to the limited number of CoAP servers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.5
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• pp.1102-1109
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• 2017

In Train Control Network(TCN), to support advanced services beyond control applications, it was revised to support high speed ethernet as IEC 61375-2-5(ETB) and IEC 61375-3-4(ECN). And Train Topology Discovery Protocol(TTDP) was included by which train-consist can be automatically configured. Meanwhile, to adopt wireless LAN as an next onboard network, TTDP need to be modified to reflect the characteristics of WLAN. This paper proposed a TTDP for WLAN using transmission power control and the number of HELLO-ACK handshake. And it determined whether the TTDP executed using the two WLAN interfaces having different bandwidths is correct or not. The proposed TTDP can allow to reduce interference from other nodes. For evaluation of performance of TTDP, NS-2 was used. The evaluation result shows the high reliability of the TTDP in wireless environment.