• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.4 s.310
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• pp.80-87
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• 2006

Recently, the distribution and using of the digital multimedia contents are easy by developing the internet application program and related technology. However, the digital signal is easily duplicated and the duplicates have the same quality compare with original digital signal. To solve this problem, there is the multimedia fingerprint which is studied for the protection of copyright. Fingerprinting scheme is a techniques which supports copyright protection to track redistributors of electronic inform on using cryptographic techniques. Only regular user can know the inserted fingerprint data in fingerprinting schemes differ from a symmetric/asymmetric scheme and the scheme guarantee an anonymous before recontributed data. In this paper, we present a new scheme which is the detection of colluded multimedia fingerprint by neural network. This proposed scheme is consists of the anti-collusion code generation and the neural network for the error correction. Anti-collusion code based on BIBD(Balanced Incomplete Block Design) was made 100% collusion code detection rate about the average linear collusion attack, and the hopfield neural network using (n,k)code designing for the error bits correction confirmed that can correct error within 2bits.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.5 s.311
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• pp.68-75
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• 2006

Multimedia fingerprinting protects multimedia content from illegal redistribution by uniquely marking every copy of the content distributed to each user. Differ from a symmetric/asymmetric scheme, fingerprinting schemes, only regular user can know the inserted fingerprint data and the scheme guarantee an anonymous before recontributed data. In this paper, we present a scheme which is the algorithm using LDPC(Low Density Parity Check) for detection of colluded multimedia fingerprint and correcting errors. This proposed scheme is consists of the LDPC block, Hopfield Network and the algorithm of anti-collusion code generation. Anti-collusion code based on BIBD(Balanced Incomplete Block Design) was made 100% collusion code detection rate about the linear collusion attack(average, AND and OR) and LD% block for the error bits correction confirmed that can correct error until AWGN 0dB.

• The Korean Journal of Financial Management
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• v.17 no.2
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• pp.71-98
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• 2000

본 연구는 1988년 6월부터 1994년 12월까지 우리나라 주식시장에 상장된 267개 최초공모주 를 대상으로 3년간 성과를 분석하고 그리고 이들 기업들이 채택한 이익관리방법에 따라 성과에 차이가 나는지를 분석하였다. 실증분석 결과, 누적초과수익률(CAR)로 추정한 최초공모주의 장기성과는 양(+)의 초과성과를 매입보유초과수익률(BHAR)로 추정한 경우에서는 저성과를 보였으나 통계적으로 유의하지는 않았다. 그리고 공개기업의 이익관리방법에 따라 성과에 차이가 나는지를 보기위해 표본기업 267개 기업중 기업의 결산시점이 달라 분석이 어려운 기업들을 제외한 후 219개 기업을 표본으로 하여 누적초과수익률(CAR)과 매입보유초과수익률(BHAR)로 분석한 결과, 두 모형 모두에서 기업의 이익을 공격적으로 관리한 기업(DCA2)의 성과가 이익을 보수적으로 관리한 기업(DAC1)의 성과보다 낮게 나타났으나 통계적으로 유의하지는 않았다. 이상의 결과에 대해 명확한 해석을 내리기에는 기업의 제반환경 및 여건 등이 영향을 미칠 수 있어 어려움이 따르나 고려할 수 있는 이유 중 하나로 최초공모주 기업들이 공개에 앞서 기업성과를 과대계상하거나 또는 매출액 및 이익부풀리기 등과 같은 분식회계처리방법이 한 요인이 된 것으로 해석할 수 있다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1991.11a
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• pp.5-18
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• 1991

유한체상의 이산 대수 문제에 안전성의 기반을 둔 ID 기본 암호 시스팀에 대해 연구하고 실제적인 예로써 시스팀의 기능을 실현한다. 기반이 되는 암호 및 서명 방식으로는 EIGamal의 시스팀을 이용한다. 그리고 사용자들의 공모로 인한 시스팀에의 공격 형태를 분석하여 이 시스팀의 안전성에 관한 조건을 유도한다.

• The KIPS Transactions:PartC
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• v.19C no.1
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• pp.63-70
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• 2012

To ensure privacy of individual information in remote healthcare service, health data should be protected through a secure technology such as encryption scheme. Only user who delegated decryption right can access to sensitive health data and delegator needs capability for revocating access privilege. Recently, in ubiquitous environment, CP-ABTD(Ciphertext-Policy Attribute-Based Threshold Decryption with Flexible Delegation and Revocation of User Attributes) which extends CP-ABE(Ciphertext-Policy Attribute-Based Encryption) has been proposed for these requirements. In this paper, we construct remote healthcare monitoring system with delegation and revocation capability for attribute in CP-ABTD. Finally, we analyze collusion attack between users in our system.

• Convergence Security Journal
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• v.19 no.3
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• pp.71-79
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• 2019

The demand of smart cars is increasing rapidly. International stand organize such as 3GPP and 5GAA are proposing standard communication protocvols for connected-car, and automotive network infrastructure. But Smart car network have many security threats and more dangerous against the existed wire communication network. Typically, peripheral devices of a smart car may disguise their identity and steal location information and personal information about the vehicle. In addition, the infrastructure elements around smart cars can conspire and put driving cars in danger, threatening lives. This is a very serious security threat. Therefore, in order to solve these problems, we proposed a system that is secure from collusion and tampering attacks using attribute-based authorize delegation method and threshold encryption algorithms. We have demonstrated using a semantic safety model that the proposed system can be safe from collusion attack.

• Convergence Security Journal
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• v.8 no.1
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• pp.19-26
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• 2008

In wireless sensor networks, an adversary can launch the wormhole attacks, where a malicious node captures packets at one location and tunnels them to a colluding node, which retransmits them locally. The wormhole attacks are very dangerous against routing protocols since she might launch these attacks during neighbor discovery phase. A strategic placement of a wormhole can result in a significant breakdown in communication across the network. This paper presents a compromise-resilient tunneled packet filtering method for sensor networks. The proposed method can detect a tunneled message with hop count alteration by a comparison between the hop count of the message and one of the encrypted hop counts attached in the message. Since the proposed method limits the amount of security information assigned to each node, the impact of wormhole attacks using compromised nodes can be reduced.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.195-199
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• 2008

We present an attack which forges a credential without the help of the credential issuer in the protocol designed by Nakazato, Wang and Yamamura at ASIAN 2007 The attack avoids using the credential issuer's private key by taking advantage of the property of bilinear pairing. Implication of this collusion attack by user and verifiers also discussed.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.05a
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• pp.167-170
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• 2021

현재, 주요 선진국들을 포함하여 Google과 IBM과 같은 국제 대기업들을 필두로 양자 컴퓨터 개발에 전폭적인 투자들을 하고 있다. 양자 컴퓨터는 특정 분야에 있어 월등한 계산 능력을 보여주며, 기존 컴퓨터에서는 해결할 수 없던 몇몇 문제들을 빠른 시간 내에 해결한다. 이러한 양자 컴퓨터의 등장은 기존 컴퓨터에서는 사실상 풀 수 없는 암호 알고리즘들을 빠른 시간 내에 해결하여 암호학계에 큰 위협이 되고 있다. 현재 사용하고 있는 대부분의 공개키 암호 알고리즘인 RSA와 ECC(Elliptic Curve Cryptography) 또한 공격 대상이다. NIST에서는 다가오는 양자 컴퓨터 시대에 대비하여 양자내성암호 공모전을 주최하였으며 현재 라운드 3에 도입하였다. 본 논문에서는 라운드 3의 후보 알고리즘인 코드기반암호를 공격하는 ISD(Information Set Decoding) 알고리즘에 관한 동향을 조사하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.4
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• pp.617-628
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• 2022

Ascon is one of the final round candidates of the NIST lightweight cryptography contest, which has been underway since 2015, and supports hash modes Ascon-Hash and Ascon-Xof. In this paper, we develop a MILP model for collision attack on the Ascon-Hash and search for a differential trail that can be used in a quantum setting through the model. In addition, we present an algorithm that allows an attacker who can use a quantum computer to find a quantum free-start collision attack of 3-round Ascon-Hash using the discovered differential trail. This attack is meaningful in that it is the first to analyze a collision attack on Ascon-Hash in a quantum setting.