• Journal of KIISE:Computer Systems and Theory
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• v.31 no.8
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• pp.465-472
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• 2004

Proxy signatures is a signature scheme that an original signer delegates one's signature capability to a proxy signer, and then the proxy signer creates a signature on behalf of the original signer. Delegation of authority is a common practice in the real world, in particular, it happens naturally in hierarchical groups such as company, bank and army, etc. In this paper, we propose a new dynamic multi-proxy signature scheme allowing repetitive delegations in a hierarchical group. We adopt multi-proxy signatures to enhance the security of proxy signature. In multi-proxy signatures, plural proxy signers can generate a valid proxy signature collectively on behalf of one original signer. In our scheme, the proxy group is not fixed but constructed dynamically according to some situations. Delegations are processed from higher level to lower level in the hierarchy using delegation tickets. When the original signer wants to delegate one's signature authority, the original signer generates a delegation ticket based on secret sharing and Diffie-Hellman problems. The delegation ticket is shared among proxy signers and then all the proxy signers can generate a valid proxy signature collectively by reconstructing the original signer's delegation ticket. If a certain proxy signer can not attend the proxy signature generating protocol, the proxy signer can also delegate repetitively his partial signature authority to the lower level participants, and then the proxies are constructed dynamically.

• ETRI Journal
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• v.26 no.6
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• pp.641-646
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• 2004

As the use of signatures for identification purposes is pervasive in society and has a long history in business, dynamic signature verification (DSV) could be an answer to authenticating a document signed electronically and establishing the identity of that document in a dispute. DSV has the advantage in that traits of the signature can be collected on a digitizer. The research question of this paper is to understand how the individual variables vary across devices. In applied applications, this is important because if the signature variables change across the digitizers this will impact performance and the ability to use those variable. Understanding which traits are consistent across devices will aid dynamic signature algorithm designers to create more robust algorithms.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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• pp.81-83
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• 2002

Group signature schemes allow a group member to sign a document on behalf of the group anonymously. In addition, in case of anonymity misuse, a group authority can recover the issuer of a signature. In this paper, we analyze the security of a group signature scheme proposed by Popescu which is a modification of the Tseng-Jan group signature scheme. We show that the scheme can't provide an important requirement of the group signature, unlikability. Thus, other members are allowed to identify whether two signatures have been issued by the same group member or not.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3911-3924
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• 2016

Compared to the classical cryptography, lattice-based cryptography is more secure, flexible and simple, and it is believed to be secure against quantum computers. In this paper, an efficient signature scheme is proposed from the ring learning with errors (R-LWE), which avoids sampling from discrete Gaussians and has the characteristics of the much simpler description etc. Then, the scheme is implemented in C/C++ and makes a comparison with the RSA signature scheme in detail. Additionally, a linearly homomorphic signature scheme without trapdoor is proposed from the R-LWE assumption. The security of the above two schemes are reducible to the worst-case hardness of shortest vectors on ideal lattices. The security analyses indicate the proposed schemes are unforgeable under chosen message attack model, and the efficiency analyses also show that the above schemes are much more efficient than other correlative signature schemes.

• Journal of the Korean Institute of Intelligent Systems
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• v.5 no.4
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• pp.33-40
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• 1995

This paper delas with the detection of freehand forgeries of signatures based on the averaged directional amplitudes of gradient vetor which are related to the overall shape of the handwritten signature and fuzzy ARTMAP neural network classifier. In the first step, signature images are extracted from the background by a process involving noise reduction and automatic thresholding. Next, twelve directional amplitudes of gradient vector for each pixel on the signature line are measure and averaged through the entire signature image. With these twelve averaged directional gradient amplitudes, the fuzzy ARTMAP neural network is trained and tested for the detection of freehand forgeries of singatures. The experimental results show that the fuzzy ARTMAP neural network cna lcassify a signature whether genuine or forged with greater than 95% overall accuracy.

• Proceedings of the CALSEC Conference
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• 2005.03a
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• pp.299-304
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• 2005

This paper is a research on the dynamic signature verification of error rate which are false rejection rate and false acceptance rate, the size of signature verification engine, the size of the characteristic vectors of a signature, the ability to distinguish similar signatures, and so on. We suggest feature extraction and comparison method of the signature verification. Also, we have implemented our system with Java technology for more efficient user interfaces and various OS Platforms.

• The Journal of Korean Association of Computer Education
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• v.8 no.4
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• pp.97-105
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• 2005

In this study, the undeniable digital multi-signature scheme based on the discrete logarithms is proposed. The proposed multi-signature scheme satisfies undeniability and is secure against active attacks such as fabrication and denial of multi-signature by signers. It is suitable for electronic election scheme in which several administrators are required. Especially in case of dispute among voters and administrators, the proposed scheme can resolve it due to the undeniable property. It can provide fair electronic election by minimizing the role of voting center, and can enable user-oriented electronic election.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.586-590
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• 2005

In order to compare the dynamic loading effects of particular trains it is necessary to use methodology that separates the two inherent aspects of the dynamic response of the total dynamic system-the characteristics of the train and a bridge. Because the train signature profile is a function of axle spacing and axle loads, it can be calculated which is independent of the characteristics of an individual bridge. Thus the use of the train signature enables a rapid comparison of the effects of different trains to be made. If the magnitude of train signature for a new train type is less than of existing trains on a route then the route will be satisfactory for the new train. This study presents a quantitative analysis of the dynamic loading effects for various domestic real trains-PMC8, PMC16, Mugunhwa passenger coach, several freight coach, KTX and TTX(Tilting Train Express)- Using the train signature.

• The Journal of Society for e-Business Studies
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• v.10 no.3
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• pp.49-65
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• 2005

This paper is a research on the dynamic signature verification of error rate which are false rejection rate and false acceptance rate, the size of signature verification engine, the size of the characteristic vectors of a signature, the ability to distinguish similar signatures, and so on. We suggest feature extraction and comparison method of the advanced signature verification. Also, we have implemented web authentication server with Java technology for supporting various OS Platforms and designed for more efficient user interfaces.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04b
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• pp.1089-1092
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• 2001

IDS 에서 가장 중요한 것은 침입을 논리적으로 모델링하고, 이것을 센싱 할 수 있는 Filter 의 개발이며 Filter 에서 발생한 이벤트들에서 특정 공격 행위를 인식할 수 있는 신호인 Signature 의 정의를 통해 이벤트 스트림에서 Signature 를 자동으로 인식할 수 있는 방법에 대한 연구가 가장 핵심적이라고 할 수 있다. 본 논문은 이러한 filter 와 Signature 에서 사용할 수 있도록 특징들이 정의 되어있는 양식으로 원시 데이터로부터 profile 을 생성 filter 와 signature 에서 탐지할 수 있는 모듈을 적용할 수 있도록 네트웍과 host input stream 등의 raw audit data 에서 특징을 추출 Feature Construction 작성에 대한 연구이다.