• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.888-892
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• 2005

현재 무선 인터넷 시장이 급속도로 발전하고 있고 여러 가지 콘텐츠 및 전자 거래 서비스가 유선상에서 제공하는 것처럼 서비스를 제공하고 있다. 국내에서는 휴대폰을 중심으로 각종 서비스들이 제공되고 있는 실정이다. 그러나 휴대폰은 유선상의 PC와 성능을 비교하면 절대적인 열세에 있다. 다시 말해서, 유선의 서비스처럼 안전한 보안을 바탕으로 제공하는 서비스가 아니라 하드웨어 성능의 열세로 인한 안전하지 못한 서비스이다. 이를 보완하기 위해 단말기 사양에 맞는 표준안들이 국제 포럼에서 계속해서 제정 중에 있으며 효과적인 보안통신을 위한 여러 연구들이 진행 중에 있다. 무선용 인증서를 사용하여 안전한 암호화 통신을 위한 연구로 무선 공개키 기반구조(WPKI :Wireless Public Key Infrastructure)가 있다. 본고에서는 이에 대해서 살펴보고 또, 무선용 프로토콜인 WAP포럼의 WAP(Wireless Application Protocol), Microsoft사의 ME(Mobile Explore) 그리고 일본 도코모사의 i-mode 중에서 가장 국제적으로 통용되어 쓰이고 있는 WAP에 대해서 살펴본다. 또한 현재 암호화 통신에서 사용되는 암호학적 안전성에 대해 논하고 안전한 무선 암호화 통신을 가로막는 요인과 해결 방안에 대해 논의한다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.3
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• pp.34-40
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• 2002

In this paper, a new encryption method for a binary image using Phase modulation and Fourier transform is proposed. For decryption we use the characteristics of square law detector. In encryption process, a key image is obtained by phase modulation of 256 level random pattern and its Fourier transformation, and input image is encrypted by Fourier transforming the multiplication of the phase modulated random pattern and phase modulated input image. The encrypted image and key image have only phase information, so they can not be copied or counterfeited and the original image can not be decrypted without the key image. To reconstruct the original image, each phase mask of the key image and the encrypted image must be placed on each path of the Mach-Zehnder interferometry with Fourier transform lens and the output image is obtained in the form of intensity in the CCD(Charge Coupled Device) camera. The real-time decryption is possible in the proposed system by use of a LCD as a phase modulator and a CCD camera as an intensity detector. The proposed method shows a good performance in the computer simulation and optical experiment as an encryption scheme.

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.312-313
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• 2005

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.2
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• pp.89-98
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• 2004

In this paper, we implement a digital holographic security card system that combines digital holographic memory using random phase encoded reference beams with electrical biometrics. Digitally encoded data including a document, a picture of face, and a fingerprint are recorded by multiplexing of holographic memory. A random phase mask encoding reference beams are used as a decoded key to protect illegal counterfeit. As a result, we can achieve a raw BER of 3.6${\times}$10-4 and shift selectivity of 4${\mu}{\textrm}{m}$ using the 2D random phase mask. Also, we develop a recording pattern and image processing which are suitable for a low cost reader without a position sensing photo-detector for real time data extraction and remove danger of fraud from unauthorized person by comparing the reconstructed holographic data with the live fingerprint data.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.1
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• pp.37-43
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• 2001

In this paper, we propose a new optical security technique using two phase masks based on interferometer. A binary random phase image is used as a reference image and the encrypted image is generated according to the phase difference between the reference image and the original image. If there is no phase difference of a same pixel position in two phase masks, interference intensity of the pixel has minimum value and if phase difference of a same pixel position in two phase masks is $\pi$, its interference intensity has maximum value. We can decrypt the original image by putting two phase masks on each of the two optical paths of the Mach-Zehnder interferometer. Computer simulation and the optical experiments show a good performance of the proposed optical security system.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.401-411
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• 2006

We propose an optical encryption/decryption technique for a security system based on 2-step phase-shifting digital holography. Phase-shilling digital holography is used for recording phase and amplitude information on a CCD device. 2-step phase-shifting is implemented by moving the PZT mirror with phase step of 0 or ${\pi}/2$. The binary data and the key are expressed with random code and random phase patterns. The digital hologram is a Fourier transform hologram and is recorded on CCD with 256 gray level quantization. We remove the DC term of the digital hologram fur data reconstruction, which is essential to reconstruct the original binary input data/image. The error evaluation fer the decrypted binary data is analyzed. One of errors is a quantization error in detecting the hologram intensity on CCD, and the other is generated from decrypting the data with the incorrect key. The technique using 2-step phase-shifting holography is more efficient than a 4-step method because 2-step phase-shifting holography system uses less data than the 4-step method for data storage or transmission. The simulation shows that the proposed technique gives good results fur the optical encryption of binary information.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.1
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• pp.35-42
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• 2022

Visible light communication (VLC) is a method of transmitting data through LED blinking and is vulnerable to eavesdropping because the illumination affects the wide range of area. IEEE standard 802.15.7 defines On-Off Keying (OOK), Variable Pulse Position Modulation (VPPM), and Color Shift Keying (CSK) as modulation. In this paper, we propose an encryption method in VPPM for secure communication. The VPPM uses an encoding method called 4B6B where 16 different outputs are represented with 6-bit. This paper extends the number of outputs to 20, to add complexity while not violating the 4B6B generation conditions. Then each entry in the extended 4B6B table is scrambled using vigenère cipher. The probability of decrypting each 6-bit data is $\frac{1}{20}$. Eavesdropper should perform $\sum\limits_{k=1}^{n}20^k$ number of different trials to decrypt the message if the number of keys is n. The proposed method can be applied to OOK of PHY II and CSK of PHY III. We further discuss the secure encoding that can be used in OOK and CSK without performance degradation.

• 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.

• The Transactions of the Korea Information Processing Society
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• v.4 no.1
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• pp.195-208
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• 1997

ISDN is network which has been developed to integrate and transfer some information(data, video, voice). In the ISDN, security problem that threat and intrusion about important information resource increase because every information is transferred in the form of digital and access of network has patiency. In this paper, for protect important information resource, studied that apply application method and encryption system to ISDN, and system structure, ITU-T Q.931 protocol were analyzed, and proposable encryption key distribution protocol, call control with hybrid encryption system for user information privacy to provide security service.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.173-180
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• 2002

Smartcard is highlighted as infrastructure that has an excellent security for executing functions such as user authentication, access control, information storage and control, and its market is expanding rapidly. But possibilities of forgery and alteration by hacking are increasing as well. This Paper makes cut off of Smartcard forgery and alteration that use angular multiplexing and private key multiplexing hologram on holographic security Encryption, and proposes system capable verfication of forgery and alteration impossible on existing smartrard by adopting smartcard chip and holographic memory chip.