• 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.30 no.3
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• pp.513-525
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• 2020

Until today, the personal information of subjects has been centralized in many companies or institutions. However, in recent days, the paradigm has gradually changed in the direction that subjects control their personal information and persue their self-sovereignty. Globally, individual data sovereignty is strengthened by the European Union's General Data Protection Regulation(GDPR) and the US California Consumer Privacy Act(CCPA). In Korea, a few alliances consist of various companies are creating technology research and service application cases for decentralized ID service model. In this paper, the current decentralized ID service model and its limitations are studied, and a improved decentralized ID service model that can solve them is proposed. The proposed model has a function of securely storing decentralized ID to the third party and a linkage function that can be interoperated even if different decentralized ID services are generated. In addition, a more secure and convenient model by identifying the security threats of the proposed model and deriving the security requirements, is proposed. It is expected that the decentralized ID technology will be applied not only to the proof of people but also to the device ID authentication management of the IoT in the future.

• Journal of the Korea society of information convergence
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• v.7 no.1
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• pp.25-46
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• 2014

After examining the current situations of financial frauds and the reasons for their occurrence in the financial institutions through examples of financial frauds in domestic and abroad, this study presents ways to prevent such financial scams. The preventive measures consist of activities before and after the occurrence of financial frauds and during normal financial operations. The activities are as follows: 1. Preventive activity should be strengthened before the occurrence of financial frauds. That is, first, the enforcement of consistent internal control is needed. Second, in order to block the probability of financial frauds involved with employees, ethics education and a reward program for inside tippers need to be run. Third, financial institutions need to apply for comprehensive insurance policy to minimize the lost in case. 2. Preventive activity should be strengthened during normal financial operations. First, self authentication system for customers needs to be introduced. Second, dealings of day, week, and month need to be thoroughly checked and the system of audit needs to be expanded. Third, message service for the information on financial frauds and their preventive measures needs to be expanded. Fourth, public notification system against examples of financial frauds needs to be expanded. 3. Preventive activity after the occurrence of financial frauds should be strengthened. First, awareness for preventive measures such as imposing penalty on the manager needs to be enhanced. Second, strict restrictions on financial frauders such as a criminal charge needs to be strengthened. Third, there should be legal devices and resolutions in order to retrieve all the money deceived by financial frauds.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.342-349
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• 2017

The purpose of this study is to empirically analyze factors which influence social and economic performance of social enterprises, and to examine the correlation of factors affecting social and economic performance. This study was conducted following the hypothesis that the organizational characteristics(organizational type, certification type, certification year, social service supply type, and external grants) of social enterprises affect social and economic performance, and that significant correlation exists between social and economic performance. This study collected the disclosure materials of 219 social enterprises certified between 2007- 2014 from the directory of the Korean Social Enterprise Promotion Agency. The study results are as follows: First, organizational characteristics affect social performance(i.e. jobs for the vulnerable classes). In addition, certification year and external grants had a positive effect on social performance. Second, the organizational characteristics affect the economic performance(i.e. sales), and certification year and external grants had a positive effect on economic performance. However, organizational type had a negative effect on the economic performance(i.e. sales). Third, analysis found a positive correlation of factors affecting social and economic performance. This study suggests the need to diversify support policies according to the number of authentication years in order to promote self-reliance and sustainability by maximizing the social and economic performance of social enterprises.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.1
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• pp.64-77
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• 2009

A proxy re-encryption scheme allows Alice to temporarily delegate the decryption rights to Bob via a proxy. Alice gives the proxy a re-encryption key so that the proxy can convert a ciphertext for Alice into the ciphertext for Bob. Recently, ID-based proxy re-encryption schemes are receiving considerable attention for a variety of applications such as distributed storage, DRM, and email-forwarding system. And a non-interactive identity-based proxy re-encryption scheme was proposed for achieving CCA-security by Green and Ateniese. In the paper, we show that the identity-based proxy re-encryption scheme is unfortunately vulnerable to a collusion attack. The collusion of a proxy and a malicious user enables two parties to derive other honest users' private keys and thereby decrypt ciphertexts intended for only the honest user. To solve this problem, we propose two ID-based proxy re-encryption scheme schemes, which are proved secure under CPA and CCA in the random oracle model. For achieving CCA-security, we present self-authentication tag based on short signature. Important features of proposed scheme is that ciphertext structure is preserved after the ciphertext is re-encrypted. Therefore it does not lead to ciphertext expansion. And there is no limitation on the number of re-encryption.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.225-231
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• 2020

This study aims to examine the efficacy of online lectures conducted by most universities in 2020 in response to the Covid-19 crisis. Furthermore, this study analyzes students' opinions regarding online lectures, thereby assessing the possible direction that future online lectures could take. This study's results indicate that online lectures can have a positive effect on learners' reading comprehension. Also, student satisfaction with online lectures was found to be quite high. Among the reasons students cited for favoring the online format were: (1) the fun presentation of class information; (2) the diversity of subjects covered; and (3) the ease of using the Internet. Among the improvements made for enhancing online lectures were technical enhancements (such as fixing attendance check authentication errors) and stabilizing the playback of lecture videos. By way of concluding, this study claims that professors who are familiar with giving lectures in person should come to recognize that online lectures are not simply another option, but are essential for the future. As such, the academic community must focus on developing online content as a way to further higher education's development in meeting the academic demands of both the present and the future.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.10
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• pp.309-318
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• 2023

Recently, each country has been moving to introduce an LCA (Life Cycle Assessment) to regulate greenhouse gas emissions. The LCA is a mean of measuring and evaluating greenhouse gas emissions generated over the entire life cycle of a vehicle. Reliable data for each electric vehicle component is needed to increase the reliability of the LCA results. To this end, studies on life cycle evaluation models using blockchain technology have been conducted. However, in the existing model, key product information is exposed to other participants. And each time parts data information is updated, it must be recorded in the blockchain ledger in the form of a transaction, which is inefficient. In this paper, we proposed a DID(Decentralized Identity)-based data collection model for LCA to collect vehicle component data and verify its validity effectively. The proposed model increases the reliability of the LCA by ensuring the validity and integrity of the collected data and verifying the source of the data. The proposed model guarantees the validity and integrity of collected data. As only user authentication information is shared on the blockchain ledger, the model prevents indiscriminate exposure of data and efficiently verifies and updates the source of data.