• Journal of the Korea Institute of Information Security & Cryptology
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• v.10 no.4
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• pp.47-57
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• 2000

This paper proposes efficient anonymous fingerprinting with improved automatic identification of redistributors in electronic commerce of digital contents. The proposed scheme by Domingos in Eletronic Letters is inefficient in electronic commerce, because of pass numbers in registration protocol and exponential computations in identification protocol. Our scheme is reduced 2-pass in registraton protocol and is required only 1 time exponential computation than his in identification protocol. According to electronic commerce of digital contents used in ordinary life, our schemes values are increased.

• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.563-568
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• 2004

In the secret sharing scheme, the reconstruction secret must to exposed to participants. In order to enforce the same secret sharing schemes, a new secret have to regenerate and redistribute for participants. Such a regeneration process is inefficient because of the overhead in the regeneration. In this paper, we proposed efficient secret regeneration scheme by eigenvalue. it can be also redistribution without revealing with other participants.

• Journal of KIISE:Information Networking
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• v.27 no.1
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• pp.48-57
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• 2000

The need for high bandwidth, very dynamic secure internet multicast communications is increasingly evident in a wide variety of commercial, government, and internet communities. One of the most recently researches is mainly about the group key distribution schemes[1,3,4,5]. In this paper, we survey related group key distribution schemes and propose a new scalable distributed group key distribution scheme which is one of the most important parts in internet multicast environment. Then, we add this scheme to the existing multicast applications and analysis the test results. The proposed SDGD minimizes the times required to distribute and redistribute keys for joining and leaving the multicast group.

• Journal of the Korea Society of Computer and Information
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• v.14 no.3
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• pp.103-111
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• 2009

IEEE 802.16e(Wibro) standard, providing robust mobile realtime data transmission technology, requires of faster and smooth execution of security mechanisms, such as key distribution and user authentications, during base station hopping. In particular, key management mechanisms such as redistribution and regeneration have an impact on digital contents transmission and realtime data transmission, not only in 802.16e environment, but also in typical transmission environment as well. This paper presents traffic management mechanisms designed to realtime digital contents (such as IPTV) transmission efficiency and increase the QoE by utilizing OKTEK methodology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.436-444
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• 2011

As practical use degree of multicasting increase, security for multicast is recognized as an important issue. Previous research in the area of secure multicast has mainly focused on group key management. The most important thing about the security of multicast is that only authorized members of this group will be able to access the data. The member of access to multicast communication is to use cryptography with a common shared session encryption key. We propose decentralized group key management based on agent for dynamic multicast with large groups and frequent joins or leaves in this paper. Whole group divide to several subgroup using agent technology and each agent manage members of each subgroup. Also, when rekeying updates that using one-way hash function can prevent the key exposure, and reduce the key distribution delay.

• Journal of the Korea Society of Computer and Information
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• v.15 no.7
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• pp.57-66
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• 2010

Due to the advancement of IPTV technologies, open IPTV services are a step closer to becoming reality. In such service environment, users are able to enjoy IPTV services using a variety of devices available at their home domain. However, it is impossible to get such flexible services at their convenience unless each of devices is individually connected to Set-Top-Box (STB) because of Conditional Access System (CAS) or service providers otherwise allow STB to freely distribute decoded contents to every user devices attached to STB. In this paper, we propose a key management scheme for securely distributing contents from STB to multiple user devices at home domain. The proposed scheme also makes the service providers be able to control the access rights to each of user devices without installing individual STBs. It is achieved by computationally dividing a private key of RSA signature scheme into three parts and thus makes possible to distribute the contents scrambled through a underlying CAS mechanism without re-encrypting them that the existing scheme should employ. It improves significantly computation and communication complexities, maintaining it as secure as the existing schemes. Additionally, it prevents misbehaving users from illegally distributing the contents from STB to their devices available at home domain.

• Convergence Security Journal
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• v.20 no.4
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• pp.177-186
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• 2020

In current public blockchain, any node can see every blocks, so that public blockchain provider transparent property. However, some application requires the confidential information to be stored in the block. Therefore, this paper proposes a multi-layer blockchain that have the public block layer and the private block for confidential information. This paper suggests the requirement for encryption of private block. Also, this paper shows the t-of-n threshold cryptosystem without dealer who is trusted third party. Moreover, the delegated node who has key information can be withdraw the delegated node group or a new delegated node can join in the delegated node group. Therefore, the paper proposes an efficient key information resharing scheme for withdraw and join. Finally proposed scheme satisfies the requirements for encryption and fairness.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.7
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• pp.288-295
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• 2007

The illegal copying and redistribution of digitally-stored information is a crucial problem to distributors who electronically sell digital data. fingerprinting scheme is a technique which supports copyright protection to track redistributors of electronic information using cryptographic techniques. Anonymous asymmetric fingerprinting scheme prevents the merchant from framing a buyer by making the fingerprinted version known to the buyer only. And this scheme allows the buyer to purchase goods without revealing her identity to the seller. In this paper, a new anonymous asymmetric fingerprinting scheme with TTP is introduced. The buyer's fingerprint is generated by the Fingerprint Certificate Authority which is a TTP. When the seller embeds the fingerprint in the digital data, the protocol uses the homomorphic encryption scheme. Thus the seller cannot know the buyer's fingerprint and the buyer's anonymity is guaranteed by using anonymous key pair.