• 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.

• Journal of Korea Multimedia Society
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• v.7 no.9
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• pp.1263-1272
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• 2004

In this paper, we present a novel video fingerprinting implementation method to identify the source of illegal copies. The video fingerprinting is achieved by the insertion of uniform distributed random number is made by seller and buyer's identification key-in the video wavelet coefficients by their temporal wavelet transform. The proposed fingerprinting is able to detect unique fingerprint of video contents even if they have been distorted by collusion attacks and MPEG2 compression. Especially, we use characteristics of the temporal wavelet transform to assign user's embedding area. Experimental results show the traceability of unauthorized distribution of video contents and its robustness to various collusion attacks and MPEG2 compression.

• 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.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.338-340
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• 2003

Certified E-mail 프로토콜은 공정한 교환(fair exchange)을 보장하기 위하여 신뢰된 제 3자 (Trusted Third Party, TTP)톨 사용한다. 그러므로, Certified E-mail을 사용하는 유저들은 원격지의 TTP를 완전히 신뢰(fully-trust)해야 한다. 만약 TTP가 훼손되거나 유저와 공모하여 악위적인 행동을 한다면 Certified E-mail 프로토콜의 공정성(fairness)은 붕괴된다. 본 논문에서는 Threshold secret sharing을 사용하여 TTP의 신뢰성을 분산시킨 강건한 Certified E-mail 프로토콜을 제안한다. 분산된 TTP(Distributed TTP, DTTP)를 사용하므로써 유저가 공모하는 악위적인(malicious) TTP에 대한 공격을 막을 수 있으며 어느 한 DTTP가 훼손되더라도 전체 프로토콜에 영향을 주지 못한다.