• Journal of the Institute of Convergence Signal Processing
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• v.3 no.2
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• pp.23-29
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• 2002

In this paper we proposed the user identification system using hybrid biometric information and non-contact IC card to improve the accuracy of the system. The hybrid biometric information consists of the face image, the iris image, and the 4-digit voice password of user. And the non-contact IC card provides the base information of user If the distance between the sample hybrid biometric Information corresponding to the base information of user and the measured biometric information is less than the given threshold value, the identification is accepted. Otherwise it is rejected. Through the result of experimentation, this paper shows that the proposed method has better identification rate than the conventional identification method.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.326-333
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• 2005

Phase-only encryption scheme using exclusive-OR rules in Fourier plane and a single path decryption system are presented. A zero-padded original image, multiplied by a random phase image, is Fourier transformed and its real-valued data is encrypted with key data by using XOR rules. A decryption is simply performed based on 2-1 setup with spatial filter by Fourier transform for multiplying phase-only encrypted data by phase-only key data, which are obtained by phase-encoding process, and spatial filtering for zero-order elimination in inverse-Fourier plane. Since the encryption process is peformed in Fourier plane, proposed encryption scheme is more tolerant to loss of key information by scratching or cutting than previous XOR encryption method in space domain. Compare with previous phase-visualization systems, due to the simple architecture without a reference wave, our system is basically robust to mechanical vibrations and fluctuations. Numerical simulations have confirmed the proposed technique as high-level encryption and simple decryption architecture.

• Journal of Korea Multimedia Society
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• v.18 no.12
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• pp.1462-1467
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• 2015

Pixel values of original image can be changed by XORing pixel values of original image and pixel values of the basis image obtained by pseudo random sequences. This is a simple method for image encryption. This method is an effect method for easy hardware implementation and image encryption with high speed. In this paper we propose a method to obtain basis image with pseudo random sequences with large nonlinearity using nonlinear cellular automata and maximum length linear cellular automata. And experimental results showed that the proposed image encryption scheme has large key space and low correlation of adjacent cipher pixel values.

• Proceedings of the KAIS Fall Conference
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• 2005.05a
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• pp.143-146
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• 2005

본 논문에서는 동영상 데이터 암호화를 위해 비디오 데이터의 I-프레임 암호화 기법을 제안한다. 또한 시스템 서버에서 암호화된 멀티미디어 데이터를 클라이언트 시스템에서 사용자가 실행할 때 자동으로 사용자 인증과 데이터의 복호화를 수행할 수 있도록 하는 라이선스 에이전트를 제안한다. 라이선스 에이전트는 사용자의 멀티미디어 데이터의 실행 시 공유 키 풀(shared key pool)을 이용한 PKI(Public Key Infrastructure)기반의 사용자의 인증과 멀티미디어 데이터의 암호 및 복호화를 수행한다. 또한 비밀키 기반의 공개키 분배 시스템을 이용하여 키의 누출을 미연에 방지하고 키의 누출 시 그 경로를 추적할 수 있도록 하였다.

• Journal of Digital Contents Society
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• v.6 no.2
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• pp.95-99
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• 2005

Recently it is important to protect the digital contents copyright because the multimedia industry is growing rapidly and the network technology is highly developed. Current digital content protection methods have disadvantage that there is very hardly accessible to the digital contents and also it has a limit that it cannot protect the contents once the encrypted contents decrypt. In order to solve this problem, digital watermarking technology has been introduced. This study presents the trend of digital watermarking technology, especially standardization and the trend of digital watermarking algorithms.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1112-1115
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• 2010

VoIP를 위한 개방형 규약 중 SIP는 IETF에서 정의한 시그널링 규약으로 IP 네트워크에서 음성, 영상의 호와 같은 멀티미디어 통신 세션을 제어하기 위해 널리 사용한다. 공격자는 SIP의 취약점을 이용한 전화번호 스캐닝, 사용자 암호를 알아내기 위한 사전공격, 콜 플러딩 공격을 통해 VoIP 서비스 정보를 절취하거나 이용을 방해 할 수 있다. 본 논문에서는 VoIP 환경의 SIP 스캐닝, 콜 플러딩, 그리고 무차별 대입 공격을 분석하고 대응방안을 제시한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.751-754
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• 2011

최근 개인이 작성한 글과 사진, 동영상 등의 자료를 시간과 장소에 따라 저장 할 수 있는 라이프 로그 서비스들이 증가하고 있다. 이러한 정보들은 개인의 일상생활을 기록하는 것으로 민감한 프라이버시임에도 불구하고 관리에 취약하다. 스마트폰 환경에서 데이터를 저장하기 위해 SQLite를 이용하고, 이를 암호화하기 위한 방안으로 SEE와 SQLCipher가 있지만 전체 데이터를 암호화하는 방식으로 중요하지 않은 데이터까지 암호화하여 저장한다. 본 논문은 개인 정보 보호를 위한 방안으로 SQLite에서 SEED 암호를 이용하여 주요한 개인 정보를 컬럼 단위로 암호화한다. 즉 라이프로그 데이터를 개인 프라이버시 중요도에 따라 분류하고, 분류된 데이터 중에서 중요한 데이터만 선택적으로 암복호화 함으로써 기존 데이터 암호화 방식에 비해 암복호화에 소모되는 연산 시간을 감소시키고 라이프로그 데이터의 개인 정보 보안을 강화시키고자 한다.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.3
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• pp.1-11
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• 2017

The main source of water pollution in Doam Lake is turbid incoming water from upland fields in the upper watershed. The large scale, elevation, and slope of this region means that it is inaccessible, and it is difficult to collect information and update data. Field survey results show that there is a difference between classification of upland fields and grasslands in the cadastral data and land-cover map. In this study, MODIS NDVI was calculated from May 2000 to September 2015 in order to improve classification accuracy of upland fields.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.775-781
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• 2013

N-screen is a Service that can be provide for One Service Multi Device. If the network is changed or if the device is changed after authentication the device fits seamlessly send footage. Security threats that occur here have a problem with user authentication. In this paper proposes available in a multi-device the authentication system. Homomorphic Encryption Algorithm of authentication scheme used. Among the authentication mechanism that already exists is a simple and lightweight authentication mechanism. In addition, N-screen service that uses multiple devices is simple authentication process of the device. Review the results of proposed authentication protocol, encryption algorithm to process a small storage capacity and is easy to work in low processor. And was suitable for use with multiple devices.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.5
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• pp.845-853
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• 2022

As the memory capacity of smartphone increases, the type and amount of privacy stored in the smartphone is also increasing. but recently there is an increasing possibility that various personal information such as photos and videos of smartphones may be leaked due to malicious apps by malicious attackers or other people such as repair technicians. This paper analyzed and studied the security and vulnerability of these vault apps by analyzing the cryptography algorithm and data protection function. We analyzed 5.3.7(June 13, 2022) and 3.3.2(December 30, 2020) versions of AppLock, the most downloaded information-hidding apps registered with Google Play, and found various vulnerabilities. In the case of access control, there was a vulnerability in that values for encrypting patterns entered by users were hardcoded into plain text in the source code, and encrypted pattern values were stored in xml files. In addition, in the case of the vault function, there was a vulnerability in that the files and log files for storing in the vault were not encrypted.