• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1969-1975
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• 2015

The Internet of Things (IoT), in which resource constrained devices communicate with each other, requires a lightweight security protocol. In this paper, we propose a new message authentication scheme using a hash tree for lightweight message authentication in the Datagram Transport Layer Security (DTLS) protocol. The proposed scheme provides lightweight secure operations compared with those of the DTLS protocol. Besides, it provides more suitable performance than the DTLS protocol for an IoT environment, thanks to the reduced use of message authentication code.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.53-61
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• 2018

Recently, technologies related to the Internet of Things have developed rapidly and research on mobile environment home network systems is actively in progress. The Internet Engineering Task Force (IETF) Working Group proposed the CoAP/6LoWPAN technology as a suitable protocol for internetworking IoT devices with the Internet in a limited environment and adopting it as a standard. However, the existing home network systems hardly include security protocols. IETF recommends DTLS(Datagram Transport Layer Security) on UDP as security protocol suitable for IoT environments. In this paper, smart home network system based on CoAP/6LoWPAN by using DTLS is implemented in mobile environments. The data transfer time is measured according to each procedure of the DTLS protocol and the need to improve DTLS protocol is suggested.

• 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.

• Convergence Security Journal
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• v.17 no.5
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• pp.3-10
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• 2017

Standard Protocol Optimized for Resource-Constrained IoT Environment Constrained Application Protocol (CoAP) supports web-based communication between a sensor node in the IoT environment and a client on the Internet. The CoAP is a Request / Response model that responds to the client's CoAP Request message by responding with a CoAP Response message from the server. CoAP recommends the use of CoAP-DTLS for message protection. However, validation of the use of DTLS in the IoT environment is underway. We analyze CoAP and DTLS security mode, evaluate performance of secure channel creation time, security channel creation step time, and RAM / ROM consumption through Cooja simulator and evaluate the possibility of real environment application.

• Convergence Security Journal
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• v.17 no.1
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• pp.53-61
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• 2017

IoT technology is evolving and related services and technologies are spreading throughout the life. These IoT technologies make life easier for users, but they also have big threats like double-edged swords. Therefore, the importance of security is emerging and related researches are actively proceeding. Existing researches have focused on reducing the computational load on the constrained devices, performing the DTLS for the end-to-end security from a network architecture perspective. In this paper, we propose a DTLS protocol that uses ECQV certificate instead of existing X.509 certificate to reduce the load of DTLS protocol from the network perspective. In addition, the proposed scheme is implemented and compared with PSK and RPK modes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1588-1596
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• 2015

In the Internet of Things (IoT), resource-constrained devices such as sensors are capable of communicating and exchanging data over the Internet. The IETF standard group has specified an application protocol CoAP, which uses UDP as a transport protocol, allows such a lightweight device to transmit data. Also, the IETF recommended the DTLS binding for securing CoAP. However, additional features should be added to the DTLS protocol to resolve several problems such as packet loss, reordering, fragmentation and replay attack. Consequently, performance of DTLS is worse than TLS. It is highly required for lightweight devices powered by small battery to design and implement a security protocol in an energy efficient manner. This paper thus discusses about DTLS performance in the perspective of energy consumption. To analyze the performance, we implemented IEEE 802.15.4 based test network consisting of constrained sensor devices in the Cooja simulator. We measured energy consumptions required for each of DTLS client and server in the test network. This paper compares the energy consumption and amount of transmitted data of each flight of DTLS handshake, and the processing and receiving time. We present the analyzed results with regard to code size, cipher primitive and fragmentation as well.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.5
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• pp.45-57
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• 2009

In this paper, we implemented the conference system based on DTLS for saving securely the VoIP, which is served sprightly in the latest, securely and tested (and also analyzed) the system. As VoIP technology development, demand of conference system is increased and the related technologies are growed. But Security protocol to protect conference service is getting late than conference technology. In this paper, we studied based on DTLS protocol that can provide function of signaling, channel security, media channel security and application of group key and apply to VoIP conference system based UDP unchanged. In this paper, we searched suggested security protocols based on DTLS can apply to conference system and implement and apply the protocol to conference system. And we tested (and also alayzed) overhead of encryption and key management mechanism.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.5
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• pp.394-400
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• 2013

WoT (Web of Things) was proposed to realize intelligent thing to thing communications using WEB standard technology. It is difficult to adapt security protocols suited for existing Internet communications into WoT directly because WoT includes LLN(Low-power, Lossy Network) and resource constrained sensor devices. Recently, IETF standard group propose to use DTLS protocol for supporting security services in WoT environments. However, DTLS protocol is not an efficient solution for supporting end to end security in WoT since it introduces complex handshaking procedures and high communication overheads. We, therefore, divide WoT environment into two areas- one is DTLS enabled area and the other is an area using lightweight security scheme in order to improve them. Then we propose a mutual authentication scheme and a session key distribution scheme for the second area. The proposed system utilizes a smart device as a mobile gateway and WoT proxy. In the proposed authentication scheme, we modify the ISO 9798 standard to reduce both communication overhead and computing time of cryptographic primitives. In addition, our scheme is able to defend against replay attacks, spoofing attacks, select plaintext/ciphertext attacks, and DoS attacks, etc.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.972-974
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• 2016

최근 전 세계적으로 IoT(Internet of Things) 기술이 활발히 연구되고 있다. IoT 환경은 임베디드나 센서 등의 시스템에 적용되는 경우가 많다. 그 특성으로 인해, 적용된 장치들은 경량화되기 때문에 통신을 위한 프로토콜로 UDP 기반 프로토콜을 많이 사용한다. UDP 기반 프로토콜은 TCP 기반 프로토콜보다 보안 기능이 미비하므로 UDP 상에서도 보안 기능을 제공해 줄 수 있는 DTLS(Datagram Transport Layer Security)가 권고된다. 하지만 DTLS는 저전력 IoT 환경을 고려하여 만들어진 프로토콜이 아니다. 그래서 저전력 IoT 환경에서 사용하기에는 힘들다. 하지만 HIGHT(HIGh security and light weigHT) 알고리즘을 사용하면 보안적인 측면을 고려하면서도 DTLS의 알고리즘인 AES(Advanced Encryption Standard)의 높은 에너지 소모량이 해결된다. 본 논문에서는 보안 측면을 고려하면서 에너지 효율까지 고려한 KISA(Korea Internet & Security Agency, 한국인터넷진흥원)의 HIGHT 암호화 알고리즘을 기반으로 DTLS를 경량화하여 저전력 기기에서 적용할 수 있는 방안을 제안한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.3
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• pp.109-120
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• 2008

VoIP utilizes the Internet for the services, and therefore it is vulnerable to intrusions and attacks. Because provided services deal with information related to privacy of users, it requires high level security including authentication and the confidentiality/integrity of signaling messages and media streams. However, when such a protocol is implemented in a VoIP phone, the implementation can have limitations due to the limited resources. The present study purposed to implement VoIP security protocols and to evaluate their performance in terms of connection quality and voice quality by applying them to SIP proxy and UA (User Agent). In the result of performance evaluation, the application of the security protocols did not lower voice quality, but connection quality was high in the DTLS based security protocol. As the protocol was applicable to signaling and media paths based on DTLS, we found that it can be a solution for the limited resources of VoIP phone.