• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.3
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• pp.545-551
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• 2012

In this paper, we propose a new cryptosystem based on the IQC depended on the complexity of class number and intractibility of factoring integer, and introduce two algorithm which reduce encryption and decryption times. To recognize the security of the cryptosystem, we take a simple example to analyze the complexities of public key and secret key and then introduce the operating process of the cryptosystem.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.253-255
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• 2017

본 논문에서는 IoT 디바이스의 인증암호를 위한 AES-GCM 암호코어를 설계하였다. AES-GCM 코어는 블록암호 AES와 GHASH 연산으로 기밀성과 무결성을 동시에 제공한다. 기밀성 제공을 위한 블록암호 AES는 운영모드 CTR과 비밀키 길이 128/256-bit를 지원한다. GHASH 연산과 AES 암호화(복호화)의 병렬 동작을 위해 소요 클록 사이클을 일치시켜 GCM 동작을 최적화 하였다. 본 논문에서는 AES-GCM 코어를 Verilog HDL로 모델링 하였고 ModelSim을 이용한 시뮬레이션 검증 결과 정상 동작함을 확인하였으며 Xilinx Virtex5 XC5VSX95T FPGA 디바이스 합성결과 4,567 슬라이스로 구현되었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.301-308
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• 2007

In this paper, we propose a new efficient multi-receiver identity-based encryption scheme from Bilinear Pairing. The proposed scheme eliminates pairing computation to encrypt a message for multiple receivers and only need one pairing computation to decrypt the ciphertext. Moreover, we show how to properly transform our scheme into a highly efficient stateless public key broadcast encryption scheme based on the subset-cover framework.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.3
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• pp.541-547
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• 2019

As leakage cases of personal information increase, the concern of personal information protection is also increasing. As a result, most applications encrypt and store sensitive information such as personal information. Especially, in case of instant messengers, it is more difficult to find database where is not encrypted and stored. However, this kind of database encryption acts as anti-forensic from the point of view of digital forensic investigation. In this paper, we analyze database encryption process of MalangMalang Talkcafe application which is one of instant messenger. Based on our analysis, we propose a decryption method and explain the meaningful information collected in the database.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.6
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• pp.119-125
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• 2005

We propose a new code-based publick key encryption scheme. It is obtained by modifying the Augot and Finiasz scheme proposed at Eurocrypt 2003. We replace the Reed-Solomon codes with general algebraic-geometry codes and employ Guruswami-Sudan decoding algorithm for decryption. The scheme is secure against Colon's attack or Kiayias and Yung's attack to which the Augot and Finiasz scheme is vulnerable. Considering basic attacks aprlied to the Augot and Finiasz scheme, we claim that the proposed scheme provides similar security levels as the Augot and Finiasz scheme was claimed to provide for given key lengths.

• Journal of Broadcast Engineering
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• v.21 no.3
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• pp.412-424
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• 2016

Broadcast encryption (BE) is a cryptographic primitive that enables a sender to broadcast a message to a set of receivers in a secure channel. The efficiency of BE is measured by three factors: ciphertext transmission cost, user storage cost, and computational cost for decryption. In general, BE is applied to the environments where a large number of receivers should be accommodated, so that the transmission cost is considered as being the most important factor. In this paper, we suggest a new BE system, using Shamir's secret sharing method, which considerable reduces the transmission cost. In comparison to the previous Subset Difference (SD) system, the transmission size of our BE is longer until $r{\leq}\sqrt{n}$, but get shorter when $r{\geq}\sqrt{n}$ for number of revoked users and n number of total users. We show that the advantage can be achieved at the slight expense of both the storage and computational costs.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.219-222
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• 2000

본 논문에서는 미국 국립표준기술연구소의 AES 개발과제 추진일정 제 2라운드에서 선정된 다섯 개의 128비트 암호 알고리듬 중에서 RC6 암호 알고리듬에 대해 ALTERA FPGA를 사용하여 하드웨어로 구현한다. RC6 암호 알고리듬을 하드웨어로 구현하는 과정에서, 키 스케줄링을 포함한 경우와 포함하지 않는 경우에 대하여 각각의 모듈에 대한 구현 방법을 기술하고, 구현된 각각의 코어가 각각 5.37MHz와 5.18MHz로 동작하며, 22개의 클럭을 사용하여 암호/복호화가 완료됨을 보여준다.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.311-316
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• 2013

256-bit block cipher XSB(eXtended Spn Block cipher) was proposed in 2012 and has a symmetric strucrure in encryption and decryption process. In this paper, we propose a differential fault analysis on XSB. Based on a random byte fault model, our attack can recover the secret key of XSB by using only two random byte fault injection. This result is the first known cryptanalytic result on the target algorithm.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.10 no.1
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• pp.89-97
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• 2000

공개키 암호 시스템 중에서 가장 널리 사용되는 RSA 암호 시스템은 키의 분배와 권리가 용이하고, 디지털 서명이 가능한 장점이 있으나, 암호화와 복호화 과정에서 512 비트 이상의 큰 수에 대한 멱승과 모듈라 감소 연산이 요구되기 때문에 처리 속도의 지연이 큰 문제가 되므로 모듈라 멱승 연산의 고속 처리가 필수적이다. 따라서 본 논문에서는 몫을 추정하여 중간 곱의 크기를 제한하는 interleaved 모듈라 곱셈 기법을 이용하여 모듈라 멱승 연산을 수행하는 고속 RSA 암호 칩을 VHDL을 이용하여 모델링하고 Faraday FG7000A 라이브러리를 이용하여 합성하고 타이밍 검증하여 단일 칩 IC로 구현하였다. 구현된 암호 칩은 75,000 게이트 수준으로 합성되었으며, 동작 주파수는 50MHz이고 1회의 RSA 연산을 수행하는데 소요되는 전체 클럭 사이클은 0.25M이며 512비트 당 처리 속도는 102.4Kbit/s였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.660-663
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• 2011

The file security function, which this paper suggests, restricts the access of an unauthorized users by using password algorithm and saving file. Saved files that are encrypted are read by decrypting them with decryption algorithm. These features are user interface to design the program for user friendly. The security function implements both file encryption and decryption programs and tests whether the experiment works or not. In addition, when a decryption is progressed and the settings of between decryption and encryption are different each other, the security function also checks the possibility of decryption. We can enhance the security on important files stored in Windows servers or personal computers by developing this program.