• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.1983-1988
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• 2006

There are gradually built on electronic commerce and business information system for the effective and automated use of internet while the mainstream of industry moves on information. It is necessary that a company should develop a electronic approval system because the business documents have application to an electronic commerce, business information system as well Currently, electronic approval system on groupware is using the way of inserting the image of an approval signature, which is vulnerable on a security by attacks of fraudulent use of electrical signature and eavesdropping on electronic documents. In this paper, we implementation XML form generator based on DTD having business documents structure for creating a valid business XML documents. we designed electronic approval system based on secured XML which transfers encrypted documents. For the security issues of written XML business documents, it makes use of the crypto algorithm having high performance transaction by the interchange of public key between a server and a client.

• Journal of KIISE
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• v.43 no.8
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• pp.933-945
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• 2016

Sharing data by multiple users on the public storage, e.g., the cloud, is considered to be efficient because the cloud provides on-demand computing service at anytime and anywhere. Secure data sharing is achieved by fine-grained access control. Existing symmetric and public key encryption schemes are not suitable for secure data sharing because they support 1-to-1 relationship between a ciphertext and a secret key. Attribute based encryption supports fine-grained access control, however it incurs linearly increasing ciphertexts as the number of attributes increases. Additionally, the decryption process has high computational cost so that it is not applicable in case of resource-constrained environments. In this study, we propose an efficient attribute-based secure data sharing scheme with outsourceable decryption. The proposed scheme guarantees constant-size ciphertexts irrespective of the number of attributes. In case of static attributes, the computation cost to the user is reduced by delegating approximately 95.3% of decryption operations to the more powerful storage systems, whereas 72.3% of decryption operations are outsourced in terms of dynamic attributes.

• Journal of Internet of Things and Convergence
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• v.6 no.2
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• pp.93-100
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• 2020

Although various home services are developed as increasing the number of home devices with wire and wireless connection, privacy infringement and private information leakage are occurred by unauthorized remote connection. It is almost caused by without of device authentication and protection of transmission data. In this paper, the devices' secret value are stored in a safe memory of a smartphone. A smartphone processes device authentication. In order to prevent leakage of a device's password, a shadow password multiplied a password by the private key is stored in a device. It is proposed mutual authentication between a smartphone and a device, and session key agreement for devices using recovered passwords on SRP. The proposed protocol is resistant to eavesdropping, a reply attack, impersonation attack.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.4
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• pp.103-109
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• 2008

Many Internet application provide the PKI(public key infrastructure)-based service to provide authentication and message integrity. Several researchers proposed PKI-based p2p network framework. However, in the real world, the use of PKI is not suitable for peer to peer network, because the peer-to-peer network is an open and dynamic network. Moreover, currently there is no nation-to-nation interoperable certificate. In this paper, we designed reliable p2p file sharing application without public key infrastructure. To do this we propose reliable public key distribution mechanism to distribute public key safely without PKI infrastructure for two-tier super-peer architecture. In our system, each peer generates and distributes its public/private key pairs, and the public key is securely distributed without PKI. The proposed mechanism is safe against MITM attack. This mechanism can be applied various P2P applications such as file sharing, IPTV, distributed resource sharing and so on

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.1
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• pp.33-43
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• 2013

The research on data mining that can manage a large amount of information efficiently has grown with the drastic increment of information. Privacy-preserving data mining can protect the privacy of data owners. There are several privacy-preserving association rule, clustering and classification protocols. A privacy-preserving association rule protocol is used to find association rules among data, which is often used for marketing. In this paper, we propose a privacy-preserving k-bits inner product protocol based on Shamir's secret sharing.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.1167-1170
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• 2008

Ad-Hoc 네트워크는 임의 디바이스들이 무선 통신을 통해서 임의 네트워크 망을 구성하여 통신 서비스를 제공받는 것을 말한다. 특히 유비쿼터스 환경에서의 언제 어디서나 통신을 하기 위해서는 이동성과 자유로운 네트워크의 조인 및 탈퇴가 이루어져야 한다. 또한 통신에서 제 3자의 위장이나 정보의 도청 그리고 안전성을 제공하기 위해서 암호화 통신이 필수적으로 요구된다. 특히 Ad-Hoc 네트워크의 디바이스간의 라우팅 구성이 유동적이라서 구성하는 디바이스간의 인증 및 키 생성과정이 필요하며, 라우팅에 대한 보안 기술의 연구는 국내/외에서 진행되어져 왔다. 본 논문에서는 기존의 안전한 라우팅 방안에 대하여 알아보고 디바이스 인증 및 키 설립을 제공하는 방식에 대하여 제안한다. 본 방식은 세션키를 설립을 위해서 키 생성 및 아이디를 기반으로 한 인증 방안을 이용한다. 그로 인해 인증서를 이용하거나 디바이스간의 인증 정보 및 상호 공유된 비밀 정보가 필요하지 않는 장점을 가지고 있다. 이와 같은 방식을 이용하므로 임의 네트워크에 조인하더라도 보안 기술을 제공할 수 있는 방안이다. 본 연구를 이용하므로 유비쿼터스 환경에서의 안전한 서비스를 제공할 수 있는 기술로 활용할 수 있다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.2
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• pp.353-360
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• 2017

The Internet of Things(IoT) security has more need than a technical problem as it needs series of regulations and faultless security system for common purposes. So, this study proposes an efficient key management in order that can be trusted IoT data in cloud computing. In contrast with a key distribution center of existing sensor networks, the proposed a federation key management of cloud proxy key server is not central point of administration and enables an active key recovery and update. The proposed key management is not a method of predetermined secret keys but sharing key information of a cloud proxy key server in autonomous cloud, which can reduce key generation and space complexity. In addition, In contrast with previous IoT key researches, a federation key of cloud proxy key server provides an extraction ability from meaningful information while moving data.

• Journal of the Korea Society of Computer and Information
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• v.18 no.10
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• pp.71-80
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• 2013

In this paper, we analyze the security vulnerability through the several attack scenarios for the MCR-MAP(Multi-Context RFID Mutual Authentication Protocol) proposed by Ahn et al. And we propose the secure mutual authentication protocol that improved a prior MCR-MAP. The suggested protocol uses the ID of the legal tag and the timestamp generated by the server, when the tag tries to authenticate. And when the tag creates the credential, we create the new secret key computing the XOR operation between the secret key shared with the server and the tag timestamp generated by the server. As a result, the proposed protocol provides the secure mutual authentication and then is safe to spoofing attack. Also it provides forward-secrecy and then is safe to offline brute-burst attack. In this paper, we compare and verify the security vulnerability of the prior and the proposed protocol through the security analysis.

• The KIPS Transactions:PartC
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• v.18C no.6
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• pp.369-378
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• 2011

To ensure data confidentiality and fine-grained access control in business environment, system model using KP-ABE(Key Policy-Attribute Based Encryption) and PRE(Proxy Re-Encryption) has been proposed recently. However, in previous study, data confidentiality has been effected by decryption right concentrated on cloud server. Also, Yu's work does not consider a access privilege management, so existing work become dangerous to collusion attack between malicious user and cloud server. To resolve this problem, we propose secure system model against collusion attack through dividing data file into header which is sent to privilege manager group and body which is sent to cloud server. And we construct the model of access privilege management using AONT based XOR threshold Secret Sharing, In addition, our scheme enable to grant weight for access privilege using XOR Share. In chapter 4, we differentiate existing scheme and proposed scheme.

• Journal of Korea Multimedia Society
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• v.20 no.2
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• pp.261-270
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• 2017

Data hiding is a way to hide the information in multimedia media such as images or video. The scheme proposed by Nguyen and Chang, was able to embed, extract, and restore the cover image and the secret data using Sudoku. But in the extracting phase, the occurrence of duplicate values in the reference matrix was found to decrease the embedding capacity of secret data. This paper has proposed a reversible data hiding scheme while maintaining the quality of the image to provide high embedding capacity using $7{\times}7$ Sudoku and Shamir's secret sharing scheme.