• International Journal of Advanced Culture Technology
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• v.10 no.2
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• pp.225-232
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• 2022

When we drive a vehicle in an IoT environment, there is a problem in that information of car users is collected without permission. The security measures used in the existing wired network environment cannot solve the security problem of cars running in the Internet of Things environment. Information should only be shared with entities that have been given permission to use it. In this paper, we intend to propose a method to prevent the illegal use of vehicle information. The method we propose is to use attribute-based encryption and dynamic threshold encryption. Real-time processing technology and cooperative technology are required to implement our proposed method. That's why we use fog computing's proxy servers to build smart gateways in cars. Proxy servers can collect information in real time and then process large amounts of computation. The performance of our proposed algorithm and system was verified by simulating it using NS2.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.195-196
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• 2020

본 논문에서는 클라우드 저장소의 민감한 데이터를 보호하기 위해 제시된 암호화 알고리즘을 이용하여 텍스트 데이터를 암호화하고 처리 속도에 대한 성능을 측정하여 기존의 방식과 비교·분석하였다. 클라우드 데이터는 사용자 로그인 정보 탈취나 SSL Strip 공격에 취약하기 때문에 이러한 보안 사고의 피해를 최소화하기 위해 데이터 암호화를 통한 데이터의 보안이 요구된다. 본 논문에서는 클라우드 전송을 위해 구글 드라이브 API를 연동했으며, 암호화 알고리즘을 텍스트에 적용하기 위해 Python 언어를 이용하여 데이터를 암호화하고 구글 드라이브에 전송하는 테스트 프로그램을 제작하여 프로젝트를 진행하였다.

• The KIPS Transactions:PartC
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• v.11C no.2
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• pp.149-156
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• 2004

Broadcast encryption schemes are applied to transmit digital informations of multimedia, software, Pay-TV etc. in public network. Important thing is that only user who is permitted before only must be able to get digital information in broadcast encryption schemes. If broadcast message transfers, users who authority is get digital information to use private key given in the advance by oneself. Thus, user acquires message or session key to use key that broadcaster transmits, broadcaster need process that generation and distribution key in these process. Also, user secession new when join efficient key renewal need. In this paper, introduce about efficient key generation and distribution, key renewal method. Take advantage of two technique of proposal system. One is method that server creates key forecasting user without user's agreement, and another is method that server and user agree each other and create key Advantage of two proposal system because uses a secret key broadcast message decryption do can and renewal is available effectively using one information whatever key renewal later.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.201-206
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• 2011

With the development and supply of digital displayers, there has been a heightened interest of late in digital photo frames, eclipsing the existing print frames. This digital photo frame was developed into a new LCD digital photo frame that can be used not only for data display but also as a surveillance monitoring equipment when combined with a CCD camera. The developed photo frame uses a one-way communication encryption method that replaces the existing two-way communication encryption method to ensure the security of the surveillance image data. This method uses the chaotic signal's one-way synchronization phenomenon, where synchronization is made for a certain amount of time, after which the synchronized data can be encrypted and decoded at any point. It can yield the same results as the two-way communication encryption method. Moreover, if the proposed method is applied to the close-range communication methods of ubiquitous devices, it will be able to obtain more efficient results.

• ETRI Journal
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• v.27 no.3
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• pp.273-279
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• 2005

Toward code division multiple access (CDMA) communications and data protection, we propose and analyze pseudorandom noise (PN) sequences generated from a 2-dimensional array structure of shift-registers. For any positive integers m and n, we construct PN sequences of period $2^{mm}-1$ using an $m{\times}n$ array of registers and show that we can generate all shifted PN sequences as required by IS-95x with the proper linear combination of available sequences.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.718-720
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• 2001

본 논문에서는 ITU-T 영상회의 프로토콜 표준안(H.323)에서 보안 프로토콜로 권고된 H.235를 기반으로 하여 사용자 인증, 비디오 및 오디오 데이터의 암호화, 암호키의 보호에 대하여 구현한다. 인증 방법으로는 패스워드 기반의 대칭키 암호 인증을 사용하고, 비디오 및 오디오 데이터의 암호화에 사용되는 암호키의 보호를 위해서는 DES와 Diffie-Hellman의 키 분배 방법을 사용한다. 또한, DES를 사용한 비디오 및 오디오 데이터의 암호화/복호화를 보여준다.

• Journal of Korea Multimedia Society
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• v.23 no.8
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• pp.1030-1039
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• 2020

The biggest feature of the online environment is anonymity. So it is difficult to identify the sender accurately in Email. So we use PGP to enhance the security of email. PGP is an e-mail encryption program that has become the standard for email security worldwide. But PGP has a weak point in security. PGP can identify users, but it is difficult to verify reliability. In PGP, the more reliable other users guarantee that user are, the more reliable they are. In the previous study, the PGP structure was implemented by utilizing the block chain to lay the foundation, and in this paper, the structure of the previous article is applied to the e-mail environment to measure up the sender's reliability, and a system is proposed that allows users to distinguish the reliability of the message.

• Journal of Korea Multimedia Society
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• v.10 no.12
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• pp.1551-1558
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• 2007

The standard of evaluating function of speech coder for mobile telecommunication can be shown in channel capacity, noise immunity, encryption, complexity and encoding delay largely. This study is an algorithm to reduce complexity applying to CDMA(Code Division Multiple Access) mobile telecommunication system, which has a benefit of keeping the existing advantage of telecommunication quality and low transmission rate. This paper has an objective to reduce the computing complexity by controlling the frequency band nonuniform during the changing process of LSP(Line Spectrum Pairs) parameters from LPC(Line Predictive Coding) coefficients used for EVRC(Enhanced Variable-Rate Coder, IS-127) speech coders. Its experimental result showed that when comparing the speech coder applied by the proposed algorithm with the existing EVRC speech coder, it's decreased by 45% at average. Also, the values of LSP parameters, Synthetic speech signal and Spectrogram test result were obtained same as the existing method.

• Journal of Korea Multimedia Society
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• v.23 no.5
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• pp.658-666
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• 2020

PGP is an encryption software designed to provide information protection, security and authentication services for online communication systems. The characteristic of behavior done on the Internet is that you don't know the other person. It is very important to protect information from someone you cannot trust. So identification of the other person is an important task. PGP uses an digital signature algorithm to verify the identity of the other party. However, it is not accurate to check the other party's credibility. PGP increases trust as other users sign more on public keys of user. In other words, credibility is not perfect. In this paper, PGP certification system that key management in Ethereum blockchain, one of the blockchain platforms, is proposed. Key management in blockchain ensures data integrity, transparency and reliability.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.666-670
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• 2001

기존의 리눅스 패스워드 인증 시스템에서는 사용자의 계정을 만들어 처음으로 로그인하여 패스워드를 생성할 때에는 사용자의 프로세스 번호와 패스워드를 생성한 시각에 해당하는 값을 seed로 하여 난수를 발생시켜서 salt값을 만든다. 이 salt값은 사용자가 서로 같은 암호를 사용할 경우 암호가 같은 값으로 저장되는걸 막기 위해서 사용하는데 시스템은 salt값과 사용자 패스워드를 단방향 DES 알고리즘을 사용하여 패스워드 파일을 암호화하여 저장한다. 그러나 패스워드 파일에 사용자암호는 암호화되어 저장되지만, salt값이 그대로 저장되기 때문에 패스워드 파일을 가져가게 된다면 사전공격 해킹툴인 John-the-ripper나 Crack 프로그램 등을 이용하여 쉬운 패스워드는 공격자에 의해 간단하게 풀려버린다. 이러한 사전공격에 대한 취약점을 해결하기 위해 암호화된 사용자 패스워드들을 시스템의 또 다른 비밀키를 사용하여 암호화하는 방법을 도입함으로써 사전공격에 강한 패스워드 인증 시스템을 설계 및 구현한다.