• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.550-552
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• 2004

분산 해시 테이블 (Distributed Hash Table) 을 사용한 P2P 시스템에서는 해시함수를 사용하며 파일과 노드의 ID를 정의하고 파일의 ID와 매핑 (mapping) 되는 ID를 가진 노드에 파일을 저장함으로써 시스템 전체에 파일을 완전히 분산시킨다. 이러한 시스템에서는 파일을 찾을 때 해시된 파일 ID로 찾기 때문에 정확한 매치 (exact match) 만 가능하다. 하지만 현재 P2P 파일 공유 시스템에서는 파일의 전체 이름을 정확히 알지 못하더라도 부분적인 키워드로 파일을 검색할 수 있도록 하는 키워드 검색 (keyword search) 이 요구된다. 본 논문에서는 분산 해시 테이블을 기반으로 하는 P2P 시스템에서 키워드 검색이 가능하도록 하는 방안을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.241-249
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• 2017

Recently, as a vehicle black box device has propagated, it has been increasingly used as a legal proof and there are the needs to verify an integrity of the video data. However, since the black box classified as the embedded system has a small capacity and low processing speed, there are limitations to the storage of video files and the integrity verification processing. In this paper, we propose a novel method for video files integrity in the black box environment with limited resources by using lightweight hash function LSH and the security of HMAC. We also present the test results of CPU idle rate at integrity verification in vehicle black box device by implementing this method, and verify the effectiveness and practicality of the proposed method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.187-189
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• 2018

In this paper, the optimal design conditions for hardware implementation of the Secure Hash Algorithm3-512 (SHA3-512) hash function were analyzed. Five SHA3-512 hash cores with data-path of 64-bit, 320-bit, 640-bit, 960-bit, and 1600-bit were designed, and their functionality were verified by RTL simulation. Based on the results synthesized with Xilinx Virtex-5 FPGA device, we evaluated the performance of the SHA3-512 hash cores, including maximum frequency, throughput, and occupied slices. The analysis results show that the best hardware performance of SHA3-512 hash core can be achieved by designing it with 1600-bit data-path.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.100-102
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• 2005

유비쿼터스는 현재의 제한된 컴퓨팅 환경을 떠나서 시간과 장소에 구애받지 않는 자유로운 컴퓨팅 환경을 제공함으로서 각광받고 있다. 그 중 언제어디서나 정보를 주고받을 수 있으며 가격과 성능 면에서 단연 뛰어난 RFID(Radio Frequency Identification)의 중요성은 점점 증가되고 있는 추세이다. 그러나, 이와 같은 우수성에도 불구하고, 정보 유출의 위험성을 내포하고 있으며, 개인의 위치 추적이나, 비 접근 권한자의 위장행세 등의 사용자 프라이버시 보호에 대한 많은 문제점들을 수반한다. 현재까지 이와 관련된 연구들이 활발히 진행되고 있다. 특히 그 중, Ohkubo의 해시함수를 이용한 프로토콜은 프라이버시 보호 측면에서 위치추적 공격(location tracking), 전방위보안성(forward security)과 같은 문제들에 대한 해결책을 제시하고 있으나, 해시함수를 태그에 직접 구현하는 것은 현재까지는 불가능한 상태이다. 또한, Martin Feldhofer는 대칭키 암호 알고리즘인 AES(Advanced Encryption Standard)를 태그에 구현을 함으로서 암호학적인 강도를 높였으나, 위치추적 공격에 대한 문제정과 물리적 공격에 대한 가정을 하지 않은 단점을 가지고 있다. 본 논문에서는 기존연구에서의 문제점들을 보완하고자 현실적으로 구현 가능한 AES를 사용하고, 위치추적 공격, 비권한자 접근(unauthorized access) 공격과 물리적 공격으로부터 안전하며 전방위보안성을 제공하는 기법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4B
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• pp.428-434
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• 2009

Many RFID authentication protocols have been proposed to build a secure ubiquitous environment. However, existing protocols do not respond recent attacks appropriately and they perform many hash operations to authenticate a large number of tags. In this paper, we propose a hash function-based secure authentication protocol for improving efficiency in RFID system. The proposed protocol is safe to passive attacks and active attacks, and requires only 2 hash operations in a tag and 3 hash operations in a database. Accordingly, the proposed protocol is very effective in RFID system environment which is composed to low-cost tags and a database handling many tags.

• Journal of IKEEE
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• v.22 no.1
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• pp.38-45
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• 2018

An integrated cryptographic processor that efficiently integrates ARIA, AES block ciphers and Whirlpool hash function into a single hardware architecture is described. Based on the algorithm characteristics of ARIA, AES, and Whirlpool, we optimized the design so that the hardware resources of the substitution layer and the diffusion layer were shared. The round block was designed to operate in a time-division manner for the round transformation and the round key expansion of the Whirlpool hash, resulting in a lightweight hardware implementation. The hardware operation of the integrated ARIA-AES-Whirlpool crypto-processor was verified by Virtex5 FPGA implementation, and it occupied 68,531 gate equivalents (GEs) with a 0.18um CMOS cell library. When operating at 80 MHz clock frequency, it was estimated that the throughputs of ARIA, AES block ciphers, and Whirlpool hash were 602~787 Mbps, 682~930 Mbps, and 512 Mbps, respectively.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.2
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• pp.23-30
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• 2009

Recently, rotation symmetric Boolean functions have attracted attention since they are suitable for fast evaluation and show good cryptographic properties. For example, important problems in coding theory were settled by searching the desired functions in the rotation symmetric function space. Moreover, they are applied to designing fast hashing algorithms. On the other hand, for some homogeneous rotation symmetric quadratic functions of simple structure, the exact formulas for their Hamming weights and nonlinearity were found[2,8]. Very recently, more formulations were carried out for much broader class of the functions[6]. In this paper, we make a further improvement by deriving the formula for the Hamming weight of quadratic rotation symmetric functions containing linear terms.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.260-261
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• 2012

스마트 환경에 관심이 높아지면서 무선 센서 네트워크를 이용한 유비쿼터스 시스템을 실생활에 활용하려는 노력이 이어지고 있다. 무선 센서 네트워크는 무선 통신으로 정보를 수집하기 때문에 실생활에 적용할 경우 사생활 정보가 유출될 가능성을 가진다. 본 논문은 데이터 전송 과정에서 데이터가 유출되었을 때, 원본 데이터로의 해독을 어렵게 하는 해시 알고리즘을 제안한다. 제안하는 알고리즘은 단 방향 해시 함수인 MD5를 변형한 TinyMD5를 이용하여 데이터를 변환하고, MD5를 변형하면서 발생하는 해시 값 충돌 문제를 해결할 수 있는 기법을 추가하였다. 제안하는 알고리즘의 우수성을 보이기 위해 기존의 기법과 시뮬레이션을 통해 성능을 비교 평가하였다. 성능 평가 결과, 제안하는 알고리즘은 통신 에너지를 기존 알고리즘의 평균 29%만을 소모하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1251-1259
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• 2017

One-time password has been proposed for the purpose of addressing the security problems of the simple password system: fixed passwords and pre-shared passwords. Since it employs the consecutive hash values after a root hash value is registered at the server, the security weakness of the fixed passwords has been addressed. However, it has a shortcoming of re-registering a new root hash value when the previous hash chain's hash values are exhausted. Even though several one-time password systems not requiring re-registration have been proposed, they all have several problems in terms of constraint conditions and efficiency. In this paper, we propose the one - time password scheme based on a hash chain that generates one - time passwords using only two cryptographic hash functions at each authentication and satisfies the existing constraints without re-registration, Security requirements and efficiency.

• Journal of Industrial Convergence
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• v.21 no.9
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• pp.49-56
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• 2023

ID is used as identifying information and password as user authentication for ID-based authentication. In order to have a secure user authentication, the password is generated as a hash value on the client and sent to the server, where it is compared with the stored information and authentication is performed. However, if even one character is incorrect, the different hash value is generated, authentication will be failed and cannot be performed and various functions cannot be applied to the password. In this study, we generate several hash value including imaginary number of entered password and transmit to server and perform authentcation. we propose a technique can grants the right differentially to give various rights to the user who have many rights by one account. This can defend shoulder surfing attack by imaginary password and provide convenience to users who have various rights by granting right based on password.