• Journal of KIISE:Information Networking
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• v.36 no.4
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• pp.263-274
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• 2009

Decentralized group key management mechanisms offer beneficial solutions to enhance the scalability and reliability of a secure multicast framework by confining the impact of a membership change in a local area. However, many of the previous decentralized solutions reveal the plaintext to the intermediate relaying proxies, or require the key distribution center to coordinate secure group communications between subgroups. In this study, we propose a decentralized group key management scheme that features a mechanism allowing a service provider to deliver the group key to valid members in a distributed manner using the proxy cryptography. In the proposed scheme, the key distribution center is eliminated while data confidentiality of the transmitted message is provided during the message delivery process. The proposed scheme can support a secure group communication in dynamic network environments where there is no trusted central controller for the whole network and the network topology changes frequently.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.5
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• pp.3-15
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• 2003

The secure group communication enables the members, which belong to the same group, to communicate each other in a secure and secret manner. To do so, it is the most important that a group key is securely distributed among them and also group membership is efficiently managed. In detail, the generation, the distribution and the refreshment of a group key would be highly regarded in terms of low communication and computation complexity. In this paper, we show you a new protocol to generate a group key which will be safely shared within a group, utilizing the 2-party Diffie-Hellman key exchange protocol and the complete binary tree. Our protocol has less complexity of computation per group member by substituting many parts of exponentiation computations for multiplications. Consequently, each group member needs constant computations of exponentiation and multiplication regardless of the group size in the protocol and then it has less complexity of the computation than that of any other protocols.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.1144-1156
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• 2014

In Internet, IP multicast has been used successfully to provide an efficient, best-effort delivery service for group communication applications. However, applications such as multiparty private conference, distribution of stock market information, pay per view and other subscriber services may require secure multicast to protect integrity and confidentiality of the group traffic, and validate message authenticity. Providing secure multicast for group communication is problematic without a robust group key management. In this paper, we propose a group key management scheme based on the secret sharing technology to require each member by itself to generate the group key when receiving a rekeying message multicast by the group key distributor. The proposed scheme enforces mutual authentication between a member and the group key distributor while executing the rekeying process, and provides forward secrecy and backward secrecy properties, and resists replay attack, impersonating attack, group key disclosing attack and malicious insider attack.

• Journal of Communications and Networks
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• v.6 no.2
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• pp.156-162
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• 2004

In recent years, mobile ad-hoc networks have received a great deal of attention in both academia and industry to provide anytime-anywhere networking services. As wireless networks are rapidly deployed, the security of wireless environment will be mandatory. In this paper, we describe a group key management architecture and key agreement protocols for secure communication in mobile ad-hoc wireless networks (MANETs) overseen by unmanned aerial vehicles (UAVs). We use implicitly certified public keys method, which alleviates the certificate overhead and improves computational efficiency. The architecture uses a two-layered key management approach where the group of nodes is divided into: 1) Cell groups consisting of ground nodes and 2) control groups consisting of cell group managers. The chief benefit of this approach is that the effects of a membership change are restricted to the single cell group.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.439-441
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• 2002

Real-time Transport Protocol (RTP) is widely used in VoIP stacks charging the multimedia data delivery. Concerning with payload protection of RTP packets, Secure RTP has been discussed in IETF AVT group to provide confidentiality and authentication features using block ciphering and message authentication coding. However, Secure RTP only concentrates on payload protection. Signcryption is a good candidate for key agreement. This paper proposes a key establishment protocol using Signcryption and shows example implementation of a secure VoIP application based on Secure RTP with the proposed scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.6
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• pp.69-78
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• 2004

During the last decade, security models have been defined for two- and three-parity key exchange protocols. Currently there is a growing research interest in security models for group key management schemes. While various security models and provably secure protocols have been proposed for distributed group key exchange schemes, no results are hewn for centralized group key distribution schemes in spite of their theoretical and practical importance. We describe security requirements and a formal security model for centralized group key distribution scheme: we define the model on the channel controlled by adversaries with the ability of strong user corruption. In the security model, we propose a conversion module which can transform centralized tree-based group key distribution schemes in the literature to provably secure centralized tree-based group key distribution schemes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.9
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• pp.1668-1683
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• 2011

The importance of secure communication between only legitimate group members in ad hoc networks has been growing in recent years. Due to the ad hoc nature the scalability on dynamic membership change is a major concern. However, the previous models require at least O(log n) communication cost for key update per each membership change, which imposes a heavy burden on the devices. In this paper we present a scalable model that supports communication-efficient membership change in ad hoc networks by exclusionary keys and RSA functions. The multicast cost for key update is extremely low, that is O(1) , and one-to-one communications occur mostly in neighboring devices.

• Journal of KIISE:Information Networking
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• v.36 no.5
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• pp.437-455
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• 2009

In the near future, various multicast based services will be provided over clustered wireless networks. To provide multicast services in secure manner, multicast messages are encrypted by using group key which is shared by group members. Therefore, various group key management schemes have been introduced until now. Among them, tree based approach is one of the most representative paradigms in group key management. Traditional tree based approaches effectively reduce rekeying message transmissions of the key distribution center. However, they do not consider the network bandwidth used for transmitting the rekeying messages. In this paper, we firstly present formulas that describe bandwidth consumption of tree based group key management scheme. Based on our formulations, we propose a bandwidth efficient key tree management scheme for clustered wireless networks where membership changes occur frequently. Simulation results show that our scheme effectively reduces the bandwidth consumption used for rekeying compared to existing key tree schemes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3495-3501
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• 2010

Because the application simultaneously to transmit large amounts of data (Video conferencing, Internet broadcasting, Online games etc.) to multiple users increases, the importance and utilization of group communication was greater. So the security was recognized as a important issue. To provide security in multicast environment, A study of single group management server using protocol based on Key Tree Scheme was proposed. But the paper proposes secure group key management scheme to be a relatively low-overhead. Therefore proposed paper is demonstrated to be excellent by comparing the effectiveness of existing and proposed group key management scheme.

• Convergence Security Journal
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• v.8 no.1
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• pp.143-152
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• 2008

Sensor networks have a wide spectrum of military and civil applications, particularly with respect to security and secure keys for encryption and authentication. This thesis presents a new centralized approach which focuses on the group key distribution with revocation capability for Wireless Sensor Networks. We propose a new personal key share distribution. When utilized, this approach proves to be secure against k-number of illegitimate colluding nodes. In contrast to related approaches, our scheme can overcome the security shortcomings while keeping the small overhead requirements per node. It will be shown that our scheme is unconditionally secure and achieves both forward secrecy and backward secrecy. The analysis is demonstrated in terms of communication and storage overheads.