• Journal of the Korea Institute of Information Security & Cryptology
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• v.7 no.4
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• pp.3-10
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• 1997

본 논문은 기존 비밀분산방식의 악세스 구조를 조합디자인 이론의 관점에서 해석함으로써 새로운 비밀분산방식이 구성될 수 있음을 보인다. 종래의 비밀분산방식으로서는 다항식보간을 이용하는 방법, 사영기하를 이용하는 방법등이 알려져 있으나 본 논문에서는 OA(orthogonal Arrary), t-(v,k l)디자인, 그룹분할 가능한 GD(Group Divisible)디자인이 갖는 행렬구조로부터 비밀분산방식의 악세스 구조를 정합시킴으로써 비밀분산방식을 새롭게 구성하고 있다. 이와같이 구성된 비밀분산방식은 기존 방식의 비밀 사이즈가 소수의 멱승 q에 의존하고 있는 반면 본 방식의 경우 조합디자인 파라메터에 관계하고 있으므로 비밀 사이즈 선택의 융통성이 있고 잘 알려진 조합적 구조를 이용함으로써 실현이 용이한 특징을 갖는다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.2
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• pp.63-68
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• 2003

Signcryption has been proposed to provide authentication md confidentiality of a message efficiently. In the existing schemes, any recipient can unsigncrypt the signcrypted message alone. In this paper, we propose a (t,n)-threshold signcryption scheme in which at least t recipients must participate in an unsigncryption process.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1558-1561
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• 2020

In this paper, we propose a blockchain scheme to enhance fault tolerance in distributed storage blockchain systems. Traditional blockchain systems suffer from ever-increasing storage cost. To overcome this problem, distributed storage blockchain techniques have been proposed. Distributed storage blockchain schemes effectively reduce the storage cost, but there are still limitations in reducing recovery cost and fault tolerance. The proposed approach recovers multiple errors within a group by utilizing locally repairable codes with availability. This improves the fault tolerance of the blockchain systems. Simulation results show that the proposed scheme enhances the fault tolerance while minimizing storage cost and recovery cost compared to other state-of-art schemes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.479-482
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• 2022

Recently, various artificial intelligence technologies are being applied to smart factory, finance, healthcare, and so on. When handling data requiring protection of privacy, distributed learning techniques are used. For distribution of information with privacy protection, encoding private information is required. Minimal codes has been used in such a secret-sharing scheme. In this paper, we explain the relationship between the characteristics of the minimal codes for application in distributed systems. We briefly deals with previously known construction methods, and presents extension methods for minimal codes. The new codes provide flexibility in distribution of private information. Furthermore, we discuss application scenarios for the extended codes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.450-470
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• 2023

Traditional cloud computing faces some challenges such as huge energy consumption, network delay and single point of failure. Edge computing is a typical distributed processing platform which includes multiple edge servers closer to the users, thus is more robust and can provide real-time computing services. Although outsourcing data to edge servers can bring great convenience, it also brings serious security threats. In order to provide image retrieval while ensuring users' data privacy, a privacy preserving image retrieval scheme in edge environment is proposed. Considering the distributed characteristics of edge computing environment and the requirement for lightweight computing, we present a privacy-preserving image retrieval scheme in edge computing environment, which two or more "honest but curious" servers retrieve the image quickly and accurately without divulging the image content. Compared with other traditional schemes, the scheme consumes less computing resources and has higher computing efficiency, which is more suitable for resource-constrained edge computing environment. Experimental results show the algorithm has high security, retrieval accuracy and efficiency.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1297-1299
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• 2010

무선 통신에서는 무선 통신의 브로드캐스트한 특성으로 데이터의 기밀성 유지를 위한 암호화가 매우 중요하다. 특히 무선 센서 네트워크(WSN - Wireless Sensor Network)의 경우 일반적인 PC와는 다르게 다양한 환경에 위치할 수 있어 공격자에게 더 쉽게 노출 될 수 있는 문제점을 가지고 있다. 이런 환경에서 미리 저장된 해쉬 함수나 비밀 값에 의존한 키 분배를 할 경우 저장된 값이 노출될 경우 심각한 문제를 초래하게 된다. 그리고 D-H 키 분배 알고리즘의 경우 키 값을 안전하게 도출을 할 수 있지만 키를 도출한 대상에 대한 인증의 부재와 멀티 홉 환경에서 중간자 공격에 취약한 문제점을 드러내고 있다. 본 논문에서는 이런 문제를 해결하기위해 기존 연구를 응용하여 멀티 홉 환경에서 무선 통신의 특성을 이용한 비밀값 공유와 제 3의 노드를 이용한 간단한 인증이 가능한 기법을 제안한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.247-248
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• 2022

본 논문에서는 군사용 전술통신 분야에서 활용성이 증대되고 있는 애드혹 네트워크에 적용 가능한 비밀분산 기반의 노드 인증 기법을 제안한다. 필드에 전개되기 이전에 네트워크를 형성할 각 노드는 지수형 분산비밀키과 원본비밀키를 저정하고, 필드에 배치된 이후 네트워크 형성 초기단계에서 비밀분산의 원본비밀키 정보 복원 연산을 통해 다수 노드에 대한 동시 인증을 실시한다. 그리고 인증과정에서 원본비밀키 복원 연산을 방해하는 노드를 원본비밀키 복원 연산을 수행하기 이전에 PUF값을 활용하여 탐지한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1052-1055
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• 2007

비밀 분산법은 암호화된 정보를 해독하는데 필요한 비밀 키를 여러 조각(share or shadow)으로 나누어서 권한이 있는 다수의 참여자에게 분산시키고 키의 복원이 필요할 때 비밀 정책에 따른 참여자들이 모여서 키를 복구하는 암호 프로토콜이다. 비밀 분산법의 특징은 비밀 키의 손실을 방지하는 차원도 있지만 그보다는 비밀 키를 가진 참여자의 권한을 분배함으로써 권한의 오남용을 방지하는 것이다. 기존의 (t,n)임계 기법에서의 비밀 분산법에서는 권한이 있는 참여자 n명 중에서 t명이 모였을 경우 비밀 키를 복원함으로써 권한의 문제를 해결했지만, 이 논문에서 제안된 기법은 비밀 키를 복원하는데 변경된 (t,n)+1 임계 기법(여기서 1은 n에 포함되지 않는 별도의 참여자)에서의 비밀 분산법을 사용함으로써 비밀 키를 복원하고 권한의 문제를 해결한다. 제안된 기법은 다수의 합의가 필요로 하는 분야에 다양하게 적용될 수 있다.

• Journal of KIISE:Information Networking
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• v.31 no.4
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• pp.353-362
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• 2004

Mobile Ad-Hoc network tends to expose scarce computing resources and various security threats because all traffics are carried in air along with no central management authority. To provide secure communication and save communication overhead, a scheme is inevitable to serurely establish session keys. However, most of key establishment methods for Ad-Hoc network focus on the distribution of a group key to all hosts and/or the efficient public key management. In this paper, a secure and efficient scheme is proposed to establish a session key between two Ad-Hoc nodes. The proposed scheme makes use of the secret sharing mechanism and the Diffie-Hellman key exchange method. For secure intra-cluster communication, each member node establishes session keys with its clusterhead, after mutual authentication using the secret shares. For inter-cluster communication, each node establishes session keys with its correspondent node using the public key and Diffie-Hellman key exchange method. The simulation results prove that the proposed scheme is more secure and efficient than that of the Clusterhead Authentication Based Method(1).

• Journal of Information Technology Services
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• v.19 no.1
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• pp.145-158
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• 2020

With the development and widespread application of online shopping, the number of online consumers has increased. With one click of a mouse, people can buy anything they want without going out and have it sent right to the doors. As consumers benefit from online shopping, people are becoming more concerned about protecting their privacy. In the group buying scenario described in our paper, online shopping was regarded as intra-group communication. To protect the sensitive information of consumers, the polynomial-based encryption key sharing method (Piao et al., 2013; Piao and Kim, 2018) can be applied to online shopping communication. In this paper, we analyze security problems by using a polynomial-based scheme in the following ways : First, in Kamal's attack, they said it does not provide perfect forward and backward secrecy when the members leave or join the group because the secret key can be broken in polynomial time. Second, for simultaneous equations, the leaving node will compute the new secret key if it can be confirmed that the updated new polynomial is recomputed. Third, using Newton's method, attackers can successively find better approximations to the roots of a function. Fourth, the Berlekamp Algorithm can factor polynomials over finite fields and solve the root of the polynomial. Fifth, for a brute-force attack, if the key size is small, brute force can be used to find the root of the polynomial, we need to make a key with appropriately large size to prevent brute force attacks. According to these analyses, we finally recommend the use of a relatively reasonable hash-based mechanism that solves all of the possible security problems and is the most suitable mechanism for our application. The study of adequate and suitable protective methods of consumer security will have academic significance and provide the practical implications.