• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.1
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• pp.73-83
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• 2018

There has been increasing interest from NIST and other companies in studying post-quantum cryptography in order to resist against quantum computers. Multivariate polynomial based, code based, lattice based, hash based digital signature, and isogeny based cryptosystems are one of the main categories in post quantum cryptography. Among these categories, isogeny based cryptosystem is known to have shortest key length. In this paper, we implemented Supersingular Isogeny Diffie-Hellman (SIDH) protocol efficiently on low-end mobile device. Considering the device's specification, we select supersingular curve on 523 bit prime field, and generate efficient isogeny computation tree. Our implementation of SIDH module is targeted for 32bit environment.

• Journal of the Korea Society of Computer and Information
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• v.11 no.2 s.40
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• pp.239-251
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• 2006

Zheng's signcryption scheme is a new encryptical scheme of which can save more expense than those of the current signature encryption by using digital signature and symmetric key encryption logically. The current signcryption schemes have a problem that is to be exposed the secret key of the receiver in the case of checking repudiation of origin by the third party. To solve this problem, a solution suggested in this paper is to use multi-purpose ID-based signcryption scheme with anonymity and unlinkability. This solution is safe and more efficient than current signcryption schemes because the suggested scheme keeps the security of the random oracle model as using Weil-pairing in encryption. and follows a formal proof of semantic security of the decisional Diffie-Hellman problem.

• The Transactions of the Korea Information Processing Society
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• v.5 no.8
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• pp.2083-2090
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• 1998

In this paper, we propose two authentication exchange schemes which combine public key-based mutual authentication with a Diffie-Hellman key derivation exchange. The security of key exchange of the proposed schemes depends on the discrete logarithm problem. The ,securtly of the etity authentication depends on that of the signature mechanism to be used in the proposed scheme. In comparisun with the Kerberos, X.509 exchanges, and ISO 3-way authentication protocol, the proposed schemes are not only simple and efficient. but also are resistant to the full range of replay and interceptiun attacks.

• The Transactions of the Korea Information Processing Society
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• v.6 no.12
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• pp.3613-3621
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• 1999

In this paper, we analyzed the suity of key distribution protocol based on discrete logarithm for the purpose of designing key distribution protocol systematically. We also propose the efficient key agreement protocol with direct authentication. In comparison with Station-to-Station protocol, it provides the direct authentication using the Diffie-Hellman problem without signature.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.71-80
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• 2002

To provide the confidentiality of messages transmitted over the network, the use of cryptographic system is increasing gradually and the hybrid cryptosystem, which combines the advantages of the symmetric cryptosystem and the public key cryptosystem is widely used. In this paper, we proposes a new hybrid cryptosystem capable of providing implicit authentication for the sender of the ciphertext by means of the 1-pass key distribution protocol that offers implicit key authentication, hash function and symmetric cryptosystem. Also, we describe some examples such as the Diffie-Hellman based system and the Nyberg-Ruppel based system. The proposed hybrid cryptosystem is an efficient more than general public key cryptosystems in the aspect of computation work and provides implicit authentication for the sender without additional increase of the communication overhead.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.3
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• pp.49-59
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• 2018

Smart grid system has been deployed fast despite of legal, business and technology problems in many countries. One important problem in deploying the smart grid system is to protect private smart meter readings from the unbelievable parties while the major smart meter functions are untouched. Privacy-preserving involves some challenges such as hardware limitations, secure cryptographic schemes and secure signal processing. In this paper, we focused particularly on the smart meter reading aggregation,which is the major research field in the smart meter privacy-preserving. We suggest a noisy weighted aggregation scheme to guarantee differential privacy. The noisy weighted values are generated in such a way that their product is one and are used for making the veiled measurements. In case that a Diffie-Hellman generator is applied to obtain the noisy weighted values, the noisy values are transformed in such a way that their sum is zero. The advantage of Diffie and Hellman group is usually to use 512 bits. Thus, compared to Paillier cryptosystem series which relies on very large key sizes, a significant performance can be obtained.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.1
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• pp.41-50
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• 2010

This paper proposes a mutual identification and session key exchange scheme in secure vehicular communication based on the group signature. In VANETs, security requirements such as authentication, conditional privacy, non-repudiation, and confidentiality are required to satisfy various vehicular applications. However, existing VANET security methods based on the group signature do not support a mutual identification and session key exchange for data confidentiality. The proposed scheme allows only one credential to authenticate ephemeral Diffie-Hellman parameters generated every key exchange session. Our scheme provides a robust key exchange and reduces storage and communication overhead. The proposed scheme also satisfies security requirements for various application services in VANETs.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.171-175
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• 2006

Diffie-Hellman기반 키 합의 프로토콜들은 비교적 고비용의 연산인 지수연산으로 인해, 유선 네트워크 환경에 비해 저전력이고 컴퓨팅 자원이 제한되어 있는 무선 네트워크 환경에서는 비효율적이고 구현하기 어려운 문제가 있다. 이에 Yang등은 대리서버(Proxy Server)를 이용하여 Diffie-Hellman방식을 적용하면서도 단말 무선 네트워크 사용자의 지수연산부담을 감소시키는 효율적인 키 합의 프로토콜(이하 SEKAP)을 제안하였다. 그러나 SEKAP는 재전송공격(Replay Attack), 알려지지 않은 키 공유 공격(Unknown Key Share Attack), 그리고 키 노출로 인한 위장공격(Key Compromised Impersonation Attack) 등에 취약하며 전방향 안전성(Forward Secrecy)을 제공하지 못한다. 본 논문에서는 SEKAP가 위 공격들에 대해 취약함을 보이고, 세션키의 상호인증을 추가한 개선된 프로토콜을 제안한다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2002.06a
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• pp.190-194
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• 2002

Multiplication in Galois Field GF(2/sup m/) is a primary operation for many applications, particularly for public key cryptography such as Diffie-Hellman key exchange, ElGamal. The current paper presents a new architecture that can process Montgomery multiplication over GF(2/sup m/) in m clock cycles based on cellular automata. It is possible to implement the modular exponentiation, division, inversion /sup 1)/architecture, etc. efficiently based on the Montgomery multiplication proposed in this paper. Since cellular automata architecture is simple, regular, modular and cascadable, it can be utilized efficiently for the implementation of VLSI.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.581-583
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• 2017

Elliptic curve cyptography is relatively a current cryptography based on point arithmetic on elliptic curves and the Elliptic Curve Discrete Logarithm Problem (ECDLP). This discrete logarithm problems enables perfect forward secrecy which helps to easily generate key and almost impossible to revert the generation which is a great feature for privacy and protection. In this paper, we provide a lightweight Elliptic Curve Diffie-Hellman (ECDH) Key exchange generator that creates a 163 bit long shared key that can be used in an Elliptic Curve Integrated Encryption Scheme (ECIES) as well as for key agreement. The algorithm uses a fast multiplication algorithm that is small in size and also implements the extended euclidean algorithm. This proposed architecture was designed using verilog HDL, synthesized with the vivado ISE 2016.3 and was implemented on the virtex-7 FPGA board.