• The KIPS Transactions:PartA
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• v.14A no.6
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• pp.333-340
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• 2007

In multi agent systems, various inter agent communication models have been proposed, and, especially, there are several group communication schemes proposed so far, where some schemes guarantees transparent communication among the agents. However, in mobile agent environments, we require new group communication schemes that consider topology changes caused by mobile agent migrations. Also, these group communication schemes should be secure in order for them to be practical. In this paper, we propose a secure group communication scheme using the hierarchical overlay ring structure of mobile agents. The proposed scheme uses the ring channel in order to cope adaptively with the change of ring topology. The ring channel has basic information for construction of the ring and is managed only by the mobile agent platforms. Therefore, each mobile agent need not directly handle the ring channel and it can perform group communication without any consideration on the change of the ring topology.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.1
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• pp.93-104
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• 2011

A conditional access system is an essential element in IPTV services enabling service providers to allow authorized access to their services only to paid subscribers. Currently, there are two types of IPTV service models, namely PPC (pay-per-channel) and PPV (pay-per-view). However, a more desirable model would be the flexible PPC model, in which subscribers are free to choose any combination of preferred channels and add/remove channels independently. In this paper, we first point out that a previously proposed key management scheme for F-PPC is not secure. We then propose a new conditional access system using 4-level key hierarchy to realize secure F-PPC services. Compared to existing schemes, the proposed system is very efficient, just requiring O(1) communication for key update.

• STI Policy Review
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• v.4 no.2
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• pp.1-18
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• 2013

As the value and role of intellectual property increases in our knowledge-based economy, countries around the world have exerted various efforts to secure, utilize, and protect their intellectual property. The present study diagnoses the level of IP infrastructure of major OECD countries and analyzes their characteristics and impact. According to the diagnosis, the US, Switzerland, and Germany form a leading group followed by the mid-level countries of Korea, Ireland, Australia, and France, with Spain and Italy in the bottom group. In contrast to Korea's competitiveness in S&T and R&D infrastructures, its competitiveness in IP infrastructure is lower than the OECD average. This is thought to be due to Korea's IP infrastructure being hastily formed under the influence of international pressures rather than having been gradually built up by internal needs. A TFP analysis of the impact of IP infrastructure on economic growth shows IP infrastructure positively influences economic growth. Though this analysis is limited due to inability to secure sufficient data and indicators, it is a useful guide for understanding the nature and key characteristics of IP infrastructure.

• Convergence Security Journal
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• v.17 no.5
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• pp.77-85
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• 2017

In this paper, we propose a key establishment scheme for multicast CoAP security. For multicast CoAP applications, a CoAP Request message from a CoAP client is sent to a group of CoAP servers while each CoAP server responds with a unicast CoAP Response message. In this case, the CoAP Request message should be secured with a group key common to both the CoAP client and servers, while a pairwise key(unicast key) should be employed to secure each CoAP Response message. In the proposed protocol, the CoAP client and the CoAP server establish the group key and the pairwise key using the ECDH in the initial CoAP message exchange process. The proposed protocol, which is highly efficient and scalable, can replace DTLS Handshake and it can support end-to-end security by setting pairwise keys.

• Journal of the Korea Society of Computer and Information
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• v.17 no.9
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• pp.57-64
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• 2012

The existing protocols proposed in network mobility (NEMO) environment can require many computational costs and can bring about a delay of binding update. To solve these problems, in this paper we propose an authentication protocol supporting secure seamless handover in NEMO environment. The proposed protocol can handle quickly mutual authentication between a mobile router (MR) and an access router (AR), which uses group key among ARs and a master key (MK) issuing from key issuing server (KIS) for reducing the time of binding update as much as possible. In performance, the proposed protocol can process quickly binding update with little computational cost comparison with the existing binding update protocols and it results in robustness against existing attacks.

• Journal of the Korea Society of Computer and Information
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• v.17 no.4
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• pp.91-98
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• 2012

A group key exchange (GKE) protocol is designed to allow a group of parties communicating over a public network to establish a common secret key. As group-oriented applications gain popularity over the Internet, a number of GKE protocols have been suggested to provide those applications with a secure multicast channel. Among the many protocols is Yi et al.'s password-based GKE protocol in which each participant is assumed to hold their individual password registered with a trusted server. A fundamental requirement for password-based key exchange is security against off-line dictionary attacks. However, Yi et al.'s protocol fails to meet the requirement. In this paper, we report this security problem with Yi et al.'s protocol and show how to solve it.

• Journal of Information Technology Services
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• v.8 no.2
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• pp.117-136
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• 2009

Over the years a password has been used as a popular authentication method between a client and a server because of its easy-to-memorize property. But, most password-based authentication services have focused on a same password authentication scheme which provides an authentication and key exchange between a client and a server with the same password. With rapid change of communication environments in the fields such as mobile networks, home networking, etc., the end-to-end security allowing users to hold different password is considered as one of main concerns. In this paper, we consider a new authentication service of how each client with different own password is able to authenticate each other, which is a quite new service paradigm among the existing services. This new service can be used in the current or next generation network environment where a mobile user in cell A wants to establish a secure end-to-end channel with users in ceil B, C, and D using only their memorable passwords. This end-to-end security service minimizes the interferences from the operator controlled by network components. To achieve this end-to-end security, we propose an authentication and key exchange service for group users in different realm, and analyze its security in a formal way. We also discuss a generic construction with the existing authentication schemes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.47-58
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• 2002

The access control techniques, which can control unauthorized members to access to multicast service, have not been studied very often while there are a lot of on-going study on secure multicast architecture, multicast key distribution and sender authentication scheme have been studied. Multi level access control scheme in multicast can be used in a remote secure conference or to provide graduated multimedia services to each customers. In fact, multicast network has its own virtual networks according to different security levels. However, Early schemes are not effective when it protects unauthorized access in multi-access network environment. Furthermore this scheme does not provide us with hierarchical access control mechanism. This paper, therefore, proposes hierarchical access control scheme to provide the effectiveness in network layer by security level comparison. And we also suggests hierarchical key distribution scheme for multi level access control in application layer and effective hierarchical key renewal scheme in dynamic multicast environment which is easy to join and leaving the multicast group.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.149-160
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• 2011

Smart Grid is the next-generation intelligent power grid that maximizes energy efficiency with the convergence of IT technologies and the existing power grid. It enables consumers to check power rates in real time for active power consumption. It also enables suppliers to measure their expected power generation load, which stabilizes the operation of the power system. However, there are high possibility that various kinds of security threats such as data exposure, data theft, and privacy invasion may occur in interactive communication with intelligent devices. Therefore, to establish a secure environment for responding to such security threat with the smart grid, the key management technique, which is the core of the development of a security mechanism, is required. Using a hash chain, this paper suggests a group key management mechanism that is efficiently applicable to the smart grid environment with its hierarchical structure, and analyzes the security and efficiency of the suggested group key management mechanism.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.11
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• pp.2874-2892
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• 2013

Since security plays an important role in several ZigBee applications, such as Smart Energy and medical sensor applications, ZigBee Specification includes various security mechanisms to protect ZigBee frames and infrastructure. Among them, the Join and Leave operations of ZigBee are investigated in this paper. The current Join-Leave operation is protected by the network key (a kind of group key). We claim it is not adequate to employ the network key for such purpose, and propose a new Join-Leave operation protected by the application link key (a kind of pairwise key), which is based on a more efficient key management scheme than that of ZigBee. Hence, the original Join operation consists of a total of 12 command frames, while the new Join operation consists of only 6 command frames. In particular, the security of the proposed Join-Leave operation is equivalent to or better than that of the original Join-Leave operation. The new Join-Leave operation is extensively analyzed in terms of security and efficiency, and compared with the original Join-Leave operation of ZigBee.