• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.2
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• pp.15-22
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• 2004

For an ElGamal-type signature scheme using a generate g of order q, it has been well-known that the message nonce should be chosen randomly in the interval (0, q-1) for each message to be signed. In (2), H. Kuwakado and H. Tanaka proposed a polynomial time algorithm that gives the private key of the signer if two signatures with message nonces 0＜$k_1$, $k_2$$\leq$Ο(equation omitted) are available. Recently, R. Gallant, R. Lambert, and S. Vanstone suggested a method to improve the efficiency of elliptic curve crytosystem using integer decomposition. In this paper, by applying the integer decomposition method to the algorithm proposed by Kuwakado and Tanaka, we extend the algorithm to work in the case when ｜$k_1$ ｜,｜$k_2$, ｜$\leq$Ο(equation mitted) and improve the efficiency and completeness of the algorithm.

• Smart Media Journal
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• v.12 no.2
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• pp.76-82
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• 2023

In the 4th industrial revolution, the blockchain that distributes and manages data through a P2P network is used as a new decentralized networking paradigm in various fields such as manufacturing, culture, and public service. However, with the advent of quantum computers, quantum algorithms that are able to break existing cryptosystems such as hash function, symmetric key, and public key cryptography have been introduced. Currently, because most major blockchain systems use an elliptic curve cryptography to generate signatures for transactions, they are insecure against the quantum adversary. For this reason, the research on the quantum-resistant blockchain that utilizes lattice-based cryptography for transaction signatures is needed. Therefore, in this paper, we propose a blind signature scheme for the blockchain in which the contents of the signature can be verified later, as well as signing by hiding the contents to be signed using lattice-based cryptography with the property of quantum resistance. In addition, we prove the security of the proposed scheme using a random oracle model.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.6
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• pp.1329-1342
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• 2018

Recent advances in quantum computer development have raised the issue of the security of RSA and elliptic curve cryptography, which are widely used. In response, the National Institute of Standards and Technology(NIST) is working on the standardization of public key cryptosystem which is secure in the quantum computing environment. Lattice-based cryptography is a typical post-quantum cryptography(PQC), and various lattice-based cryptographic schemes have been proposed for NIST's PQC standardization contest. Among them, EMBLEM proposed a new multi-bit encryption method which is more intuitive and efficient for encryption and decryption phases than the existing LWE-based encryption schemes. In this paper, we propose a multi-bit encryption scheme with improved efficiency using LWR assumption. In addition, we prove the security of our schemes and analyze the efficiency by comparing with EMBLEM and R.EMBLEM.

• Journal of Digital Convergence
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• v.12 no.10
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• pp.253-258
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• 2014

Recently, the development of cloud computing technology is developed as soon as smartphones is increases, and increased that users want to receive big data service. Hadoop framework of the big data service is provided to hadoop file system and hadoop mapreduce supported by data-intensive distributed applications. But, smpartphone service using hadoop system is a very vulnerable state to data authentication. In this paper, we propose a initial authentication protocol of hadoop system assisted by smartphone service. Proposed protocol is combine symmetric key cryptography techniques with ECC algorithm in order to support the secure multiple data processing systems. In particular, the proposed protocol to access the system by the user Hadoop when processing data, the initial authentication key and the symmetric key instead of the elliptic curve by using the public key-based security is improved.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.961-964
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• 2012

NFC(Near Field Communication)는 10cm 이내의 거리에서 무선기기 간의 통신을 가능케 해주는 기술로 13.56 Mhz RF(Radio Frequency) 주파수 대역을 이용한 비접촉식 근거리 무선통신의 한 종류이다. 올해 출시되는 대부분의 스마트 폰에서 NFC 기능을 탑재하며, NFC기반의 모바일 결제 서비스가 가장 유망한 결제 방식으로 주목 받고 있다. 소비자는 NFC 모바일 단말기를 가지고 판매자의 POS(Point of Sale) 단말기와 근접 통신을 통해 결제를 진행하는 방식으로 다른 무선 통신 방식 (RFID, Bluetooth 등)보다 보안 취약성이 높지 않지만, 기존의 RFID 환경에서 일어날 수 있는 기술적 취약점과 비슷한 유형의 위협이 충분히 발생할 수 있으므로 유효한 보안 기술이 필요하다. 본 논문은 안전한 NFC 모바일 결제 환경을 구축하기 위한 공개키 알고리즘인 타원곡선 암호ECC(Elliptic Curve Cryptosystem)를 적용한 Bilinear Pairing을 활용해서 효율적이고 보안성도 강력한 인증 메커니즘을 제안한다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.700-702
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• 2001

As computers and networks become popular, distributing information on the Interment is common in our daily life. Also, the explosion of the Internet, of wireless digital communication and data exchange on Internet has rapidly changed the way we connect with other people. But secure mall is gamins popularity abroad and domestically because of their nature of prodding security. That is. it has been used a variety of fields such as general mail and e-mail for advertisement But, As the data transmitted on network can be easily opened or forged with simple operations. Most of existing e-mall system don't have any security on the transmitted information. Thus, security mail system need to provide security including message encryption, content integrity, message origin authentication, and non-repudiation. In this paper, we design implement secure mall system with non-repudiation service and encryption capability to provide services for certification of delivery and certification of content as well as the basic security services.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.2
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• pp.115-123
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• 2007

In cryptographic devices like a smart-card whose computing ability and memory are limited, cryptographic algorithms should be performed efficiently. Scalar multiplication is very important operation in Elliptic Curve Cryptosystems, and so must be constructed in safety against side channel attack(SCA). But several countermeasures proposed against SCA are exposed weaknesses by new un-dreamed analysis. 'Double-and-add always scalar multiplication' algorithm adding dummy operation being known to secure against SPA is exposed weakness by Doubling Attack. But Doubling Attack cannot apply to sABS receding proposed by Hedabou, that is another countermeasure against SPA. Our paper proposes new strengthened Doubling Attacks that can break sABS receding SPA-countermeasure and a detailed method of our attacks through experimental result.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3C
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• pp.293-298
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• 2008

Recently, with the development of mobile techniques and the consideration to conveniency of using, the research on Mobile RFID Reader technique is getting more and more attentions. Until now, all security authentication algorithms of RFID are algorithms about range between Tag and Reader. The range between Reader and backend DB is composed by wired networks, so it's supposed to be secure range. But it must be taken account of the problem of information security and privacy in wireless range during the design of Mobile RFID Reader. In this paper we design an blind signature scheme based on weil-paring finite group's ECC encryption scheme, and by using this blind signature we propose the anonymous authorization scheme to Mobile RFID Reader's users.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.5
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• pp.17-30
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• 2001

In this paper, we implemented a scalar multiplier needed at an elliptic curve cryptosystem over standard basis in $GF(2^{163})$. The scalar multiplier consists of a radix-16 finite field serial multiplier and a finite field inverter with some control logics. The main contribution is to develop a new fast finite field inverter, which made it possible to avoid time consuming iterations of finite field multiplication. We used an algorithmic transformation technique to obtain a data-independent computational structure of the Extended Euclid GCD algorithm. The finite field multiplier and inverter shown in this paper have regular structure so that they can be easily extended to larger word size. Moreover they can achieve 100% throughput using the pipelining. Our new scalar multiplier is synthesized using Hyundai Electronics 0.6$\mu\textrm{m}$ CMOS library, and maximum operating frequency is estimated about 140MHz. The resulting data processing performance is 64Kbps, that is it takes 2.53ms to process a 163-bit data frame. We assure that this performance is enough to be used for digital signature, encryption & decryption and key exchange in real time embedded-processor environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.12C
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• pp.1288-1298
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• 2002

To implement elliptic curve cryptosystem in GF(2$\^$m/) at high speed, a fast divider is required. Although bit-parallel architecture is well suited for high speed division operations, elliptic curve cryptosystem requires large m(at least 163) to support a sufficient security. In other words, since the bit-parallel architecture has an area complexity of 0(m$\^$m/), it is not suited for this application. In this paper, we propose a new serial-in serial-out systolic array for computing division operations in GF(2$\^$m/) using the standard basis representation. Based on a modified version of tile binary extended greatest common divisor algorithm, we obtain a new data dependence graph and design an efficient bit-serial systolic divider. The proposed divider has 0(m) time complexity and 0(m) area complexity. If input data come in continuously, the proposed divider can produce division results at a rate of one per m clock cycles, after an initial delay of 5m-2 cycles. Analysis shows that the proposed divider provides a significant reduction in both chip area and computational delay time compared to previously proposed systolic dividers with the same I/O format. Since the proposed divider can perform division operations at high speed with the reduced chip area, it is well suited for division circuit of elliptic curve cryptosystem. Furthermore, since the proposed architecture does not restrict the choice of irreducible polynomial, and has a unidirectional data flow and regularity, it provides a high flexibility and scalability with respect to the field size m.