• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.6
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• pp.665-670
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• 2006

This paper deals with a modified method of the dynamic time warping and feature points to extract various important information of the signature for the dynamic signature verification. We could achieve lower equal error rate, small and efficient feature points and fast processing time for the notification.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2407-2426
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• 2016

A group signature scheme allows any member to sign on behalf of a group. It is applied to practical distributed security communication environments, such as privacy-preserving, data mining. In particular, the excellent features of group signatures, including membership joining and revocation, anonymity, traceability, non-frameability and controllable linkability, make group signature scheme more attractive. Among these features, non-frameability can guarantee that a member's signature cannot be forged by any other (including issuer), and controllable linkability supports to confirm whether or not two group signatures are created by the same signer while preserving anonymity. Until now, only Hwang et al.'s group schemes (proposed in 2013 and 2015) can support all of these features. In this paper, we present a new dynamic group signature scheme which can achieve all of the above excellent features. Compared with their schemes, our scheme has the following advantages. Firstly, our scheme achieves more efficient membership revocation, signing and verifying. The cost of update key in our scheme is two-thirds of them. Secondly, the tracing algorithm is simpler, since the signer can be determined without the judging step. Furthermore, in our scheme, the size of group public key and member's private key are shorter. Lastly, we also prove security features of our scheme, such as anonymity, traceability, non-frameability, under a random oracle model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.2
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• pp.87-95
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• 2003

Dynamic Programming Matching (DPM) is a mathematical optimization technique for sequentially structured problems, which has, over the years, played a major role in providing primary algorithms in pattern recognition fields. Most practical applications of this method in signature verification have been based on the practical implementational version proposed by Sakoe and Chiba [9], and il usually applied as a case of slope constraint p = 0. We found, in this case, a modified version of DPM by applying a heuristic (forward seeking) implementation is more efficient, offering significantly reduced processing complexity as well as slightly improved verification performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.890-895
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• 2005

Dynamic (On-line) signature verification system consists of preprocessing, feature extraction, comparison and decision process for internal processing, and registration and verification windows for the user interface. We describe an implementation and design for an advanced dynamic signature verification system. Also, we suggest the method of feature extraction, matching algorithm, efficient user interface and an objective criteria for evaluating the performance.

• Journal of KIISE:Databases
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• v.27 no.1
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• pp.79-89
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• 2000

For processing signature file in parallel, an effective signature file declustering method is needed. The Linear Code Decomposition Method(LCDM) used for the Hamming Filter may give a good performance in some cases, but due to its static property, it fails to evenly decluster signature file when signature are skewed. In addition, it has other problems such as limited scalability and non-determinism. In this paper we propose a new signature file declustering method, called Inner-product method, which overcomes those problems in the LCDM. The Inner-product method declusters signature file dynamically based on the signature difference which is computed by using signature inner product. we show through the simulation experiment that the Inner-product outperforms the LCDM under various data workloads.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.8
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• pp.1693-1698
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• 2009

This paper is a research on the feature information using direction information and adjusting constant w for the dynamic signature verification. We could improved processing time and reduce signature database without the increase of error rate. We could confirmed these results by using statistical method T-test.

• The KIPS Transactions:PartB
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• v.10B no.4
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• pp.451-458
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• 2003

Dynamic Programming Matching (DPM) is a mathematical optimization technique for sequentially structured problems, which has, over the years, played a major role in providing primary algorithms in pattern recognition fields. Most practical applications of this method in signature verification have been based on the practical implementational version proposed by Sakoe and Chiba [9], and is usually applied as a case of slope constraint p = 0. We found, in this case, a modified version of DPM by applying a heuristic (forward seeking) implementation is more efficient, offering significantly reduced processing complexity as well as slightly improved verification performance.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.3
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• pp.32-45
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• 1998

A partitioned signature file is an enhancement of the signature file that divides all the signatures into blocks in such a way that each block contains the signatures with the same key. Its directory storesall the keys as meta information for avoiding unnecessary block accesses by examming them first before the acture searching of the blocks.. Efficient directory management is very important in large databasse environments since ist size gets larger proportionally to that of the database. In this paper, we first point out the problems in the directory management methods of the previous partitioned signature files, and then present a new one solving them. OUr method offers good features in the followint three aspects: (1) suitability for large database environments, (2) adaptability to dynamic situations, and (3) storage overhead for the directory. Moreover, we can seamlessly integrate it as a subcomponent into previously-developed general-purpose storage engines. These features show that our method is applicableto signature-based access structures for the content-based retrieval in various multimedia applications such as hypermedia systems, digital library systems, multimedia document systems, multimedia mailing systems, and so on.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1161-1170
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• 2016

In this paper, we provide an authentication technology for verifying dynamic signature made by finger on smart phone. In the proposed method, we are using the Auto-Encoder-based 1 class model in order to effectively distinguish skilled forgery signature. In addition to the basic dynamic signature characteristic information such as appearance and velocity of a signature, we use accelerometer value supported by most of the smartphone. Signed data is re-sampled to give the same length and is normalized to a constant size. We built a test set for evaluation and conducted experiment in three ways. As results of the experiment, the proposed acceleration sensor value and 1 class model shows 6.9% less EER than previous method.