• Korean Journal of Mathematics
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• v.16 no.4
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• pp.451-455
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• 2008

In this paper we give some results on the points of elliptic curves which have application to elliptic curve cryptography.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.485-489
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• 2006

In this paper, we slightly improve the Baby-step Giant-step for certain elliptic curves. This method gives the running time improvement of $200\%$ in precomputation (Baby-step) and requires half as much storage as the original Baby-step Giant-step method.

• Journal of Digital Convergence
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• v.13 no.10
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• pp.343-351
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• 2015

With the diverse services of the current M2M environment being expanded to the organizations, the corporations, and the daily lives, the possibility of the occurrence of the vulnerabilities of the security of the related technologies have become an issue. In order to solve such a problem of the vulnerability of the security, this thesis proposes the technique for applying the cryptography algorithm for the protection of the device key of the M2M environment. The proposed technique was based on the elliptic curve cryptography Through the key exchange and the signature exchange in the beginning, the security session was created. And the white box cipher was applied to the encryption that creates the white box table using the security session key. Application results cipher algorithm, Elliptic Curve Cryptography provides a lightweight mutual authentication, a session key for protecting the communication session and a conventional white-box cipher algorithm and was guaranteed the session key used to encrypt protected in different ways. The proposed protocol has secure advantages against Data modulation and exposure, MITM(Man-in-the-middle attack), Data forgery and Manipulation attack.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.6
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• pp.15-26
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• 2001

Visual cryptography is a simple method in which secret information can be directly decoded in human visual system without any cryptographic computations. When the secret image is scattered to n random shares(slides), this scheme has some week point such as pixel expansion and contrast degradation. Therefore, it is necessary to reduce the pixel expansion and improve the contrast in recovered image. In this paper, we propose a new construction method for (k, n) visual cryptography using the cumulative matrix. In case k is odd, we can construct the cumulative matrix perfectly. For even k, the contrast of special pair in decoded image can be achieved best by permitting multiple contract. The proposed method is more simple than that of S. Droste\`s in construction and the average contrast of decoded image is improved for the most part. Also, we show that the basis matrices depending on the cumulative matrix are able to be applied for the general access structure.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.105-125
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• 2005

Motivated by the field experimental designs in agriculture, the theory of block designs has been applied to several areas such as statistics, combinatorics, communication networks, distributed systems, cryptography, etc. An explicit formula and its fast computational algorithm for a class of symmetric balanced incomplete block designs are presented. Based on the formula and the careful investigation of the modulus multiplication table, the algorithm is developed. The computational costs of the algorithm is superior to those of the conventional ones.

• Journal of Korea Multimedia Society
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• v.18 no.4
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• pp.499-505
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• 2015

Security supports are a significant factor in the design of mobile ad hoc networks. In the dynamic topology where the node changes frequently, private key generation and revocation for newly joining and leaving nodes must be considered. In addition, the identities of individual nodes must be protected as well in mobile networks to avoid personal privacy concerns. This paper proposes ID-based private key revocation scheme and non-interactive key agreement scheme in anonymous MANETs. The proposed scheme provides the user privacy using pseudonyms and private key generation and revocation schemes with consideration of dynamic user changes. Therefore, our schemes can be applied in dynamic and privacy-preserving MANETs which are helpful to share multimedia data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4962-4967
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• 2010

Security of the electronic commercial transaction especially through the information communication network is gaining its significance due to rapid development of information and communication related fields. For that, some kind of cryptographic algorithm is already in use for the smart card. However, the growing needs of handling multimedia and real time communication bring the smart card into more stringent use of its resources. Therefore, we proposed a key scheduler block of the smart card to facilitate multimedia communication and real time communication.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.269-271
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• 2005

EMV was formed in February 1999 by Europay International, MasterCard International and Visa International to manage, maintain and enhance the EMV Integrated Circuit Card Specifications for Payment Systems as technology advances and the implementation of chip card programs become more prevalent. The formation of EMV ensures that single terminal and card approval processes are developed at a level that will allow cross payment system interoperability through compliance with the EMV specifications. A credit card environment of the domestic market adopted the standard Local-EMV to have the compatibility with EMV international standard and the EMV migration have been carried out b,# the step-by-step process. It may be possible to adopt various kinds of cryptographic algorithms, however, RSA public key algorithm is currently used. In this paper, as a public key algorithm for the authentication process, Elliptic Curve Cryptographic algorithm is applied to the EMV process. Implementation results is shown. and the possible changes necessary to accommodate Elliptic Curve Cryrtography is proposed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.5
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• pp.2258-2274
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• 2020

In this paper we first propose a new cryptosystem based on our data hiding scheme (2,9,8) introduced in 2019 with high security, where encrypting and hiding are done at once, the ciphertext does not depend on the input image size as existing hybrid techniques of cryptography and steganography. We then exploit our automata approach presented in 2019 to design two algorithms for exact and approximate pattern matching on secret data encrypted by our cryptosystem. Theoretical analyses remark that these algorithms both have O(n) time complexity in the worst case, where for the approximate algorithm, we assume that it uses ⌈(1-ε)m)⌉ processors, where ε, m and n are the error of our string similarity measure and lengths of the pattern and secret data, respectively. In searchable encryption, our cryptosystem is used by users and our pattern matching algorithms are performed by cloud providers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.931-934
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• 2005

The scalar point multiplication operations is one of the most time-consuming components in elliptic curve cryptosystems. In this paper, we suggest how to induce the point-quadruple (4Q) operation by improving the double-and-add method, which has been a prevailing computing method for calculating the result of a scalar point multiplication. Induced and drived numerical expressions were evaluated and verified by a real application using C programming language. The induced algorithm can be applied to a various kind of calculations in elliptic curve operations more efficiently and by a faster implementation.