• Electronics and Telecommunications Trends
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• v.33 no.6
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• pp.94-106
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• 2018

A quantum key distribution (QKD) provides in principle an unconditional secure communication unlike the standard public key cryptography depending on the computational complexity. In particular, free-space QKD can give a secure solution even without a fiber-based infrastructure. In this paper, we investigate an overview of recent research trends in the free-space QKD system, including satellite and handheld moving platforms. In addition, we show the key components for a free-space QKD system such as the integrated components, single photon detectors, and quantum random number generator. We discuss the technical challenges and progress toward a future free- space QKD system and components.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.389-395
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• 2013

As fusing IT and medical technique, the number of patients who adhere medical equipment inside of them is increasing. However there is a problem of for the third person to tap or modulate the patient's biometric data viciously. This paper suggests quantum encryption-based key distribution model to share key for the third person not to tap or modulate the patient's biometric data between patient and hospital staff. The proposed model uses one-time pad key that shares key sending random bits not direct sending message of quantum data. Also, it guarantees patient's anonymity because the biometric data of injected-device in the body doesn't be exposed unnecessarily.

• Korean Journal of Optics and Photonics
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• v.12 no.2
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• pp.71-76
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• 2001

We studied quantum cryptography based on the quantum nature of light. We must reduce the intensity of the light pulse to the single photon regime for quantum cryptographic communication. Considering the noise and the quantum efficiency of the detector, however, we have to fmd a criterion for which we are able to distinguish the error caused by eavesdropping from other system noises. By changing the bias voltage of the detector and the threshold of the signal voltage, we find the safe region for which we can distribute the quantum key with positive proof of no-eavesdropping. The quantum key we used is a four state quantum key (BB84). BB84).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.3
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• pp.1083-1097
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• 2018

This paper presents a novel range-free localization algorithm based on quantum particle swarm optimization. The proposed algorithm is capable of estimating the distance between two non-neighboring sensors for multi-hop heterogeneous wireless sensor networks where all nodes' communication ranges are different. Firstly, we construct a new cumulative distribution function of expected hop progress for sensor nodes with different transmission capability. Then, the distance between any two nodes can be computed accurately and effectively by deriving the mathematical expectation of cumulative distribution function. Finally, quantum particle swarm optimization algorithm is used to improve the positioning accuracy. Simulation results show that the proposed algorithm is superior in the localization accuracy and efficiency when used in random and uniform placement of nodes for heterogeneous wireless sensor networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.84-90
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• 2014

Secret communication has developed from analogue communication to digital one. Secret communication which is based on digital communication has been designed succeeding safety of one-time pad. One-time pad's safety is attributed to the security of secret key's mutual storage and mutual synchronization that is the key's interchange basis is one of the essential factors. This manuscript examines mathematical stability of BB84 algorithm which is one of the quantum cryptography system, and conducts transmission of quantum key. The created key suggests One-time Pad algorithm which interchanges ciphertext implemented AES's 64th round.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.293-294
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• 2007

• KNOM Review
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• v.22 no.2
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• pp.39-47
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• 2019

There are several big data-driven advanced research activities such as meteorological climate information, high energy physics, astronomy research, satellite information data, and genomic research data on KREONET. Since the performance degradation occurs in the environment with the existing network security equipment, methods for preventing the performance degradation on the high-performance research-only network and for high-speed research collaboration are being studied. In addition, the recent issue of quantum computers has been a threat to security using the existing encryption system. In this paper, we construct quantum cryptography-based communication network through environment construction and high-performance transmission test that build physical security through quantum cryptography-based communication network in end-to-end high-speed research network. The purpose of this study is to analyze the effect on network performance when performing physical encryption and to use it as basic data for constructing high-performance research collaboration network.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.158-159
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• 2002

오늘날에도 RSA암호문은 현대 암호에 대부분 적용될 정도로 안전하다고 생각되어왔다. 또한 PGP(Pretty Good Privacy)라는 가장 대중적인 암호화 소프트웨어도 RSA 원리를 기반으로 하고 있다. 그러나 RSA암호화체계는 주요한 결점이 있다. 인수분해하는 것이 ＂어렵다＂라고 하지만, 결코 증명되지 않았고, 또한 인수분해를 수행하는 아주 빠른 알고리즘의 존재가 전혀 불가능하지는 않기 때문이다. 따라서 현존하는 암호화 체계보다 더 확실한 안전을 보장해주는 새로운 암호화 체계와 암호화키의 분배시스템의 필요성이 대두되고 있다. (중략)

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.197-199
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• 2023

양자 키 분배는 물리적 안전성에 기반을 두어 지속가능한 보안성을 제공한다. 양자내성암호는 양자 컴퓨터로 풀이가 어려운 문제에 기반을 둔 공개키 암호이다. 양자 키 분배 네트워크를 구성하여 안전한 통신을 구현하기 위해서는 키 조합 혹은 인증 단에서 양자내성암호의 적용이 필요하다. 본 논문에서는 양자 키 분배 네트워크의 해결 과제를 살펴보고, 이를 극복하기 위한 연구와 표준화 동향에 대해 살펴본다.

• Journal of Magnetics
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• v.16 no.4
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• pp.413-416
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• 2011

An array of FeCo nanotubes has been successfully fabricated in the pores of porous anodic aluminum oxide (AAO) templates by wetting templates method. The morphology and structure of the nanotube array were characterized by scanning electron microscopy, transmission electron microscopy and x-ray diffraction. The average diameter of the nanotubes was about 200 nm, and the length was more than 10 ${\mu}m$. Vibrating sample magnetometer and superconducting quantum interference device were used to investigate the magnetic properties of the nanotube array. Interaction between the nanotubes has been found to be demagnetizing as expected and the switching field distribution is broad.