• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.2
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• pp.211-222
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• 2023

Multivariate quadratic equations (MQ)-based public-key cryptographic algorithms are one of promising post-quantumreplacements for currently used public-key cryptography. After selecting to NIST Post-Quantum Cryptography StandardizationRound 3 as one of digital signature finalists, Rainbow was cryptanalyzed by advanced algebraic attacks due to its multiple layered structure. The researches on MQ-based schemes are focusing on UOV with a single layer. In this paper, we propose a new MQ-signature scheme based on UOV using the combinations of the special structure of linear equations, spare polynomials and random polynomials to reduce the secret key size. Our scheme uses the block inversion method using half-sized blockmatrices to improve signing performance. We then provide security analysis, suggest secure parameters at three security levels and investigate their key sizes and signature sizes. Our scheme has the shortest signature length among post-quantumsignature schemes based on other hard problems and its secret key size is reduced by up to 97% compared to UOV.

• Review of KIISC
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• v.8 no.2
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• pp.37-48
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• 1998

수많은 암호시스템과 관련 프로토콜의 안전이 소인수분해 문제의 어려움에 기반하고 있다 본 논문에서는 암호해독과 설계에 영향을 줄 수 있는 소인수분해 알고리즘에 대하여 현재까지의 연구동향과 성과를 기술하였으며, 연분수를 이용한 인수분해 알고리즘(CFRACT), QS(Quadratic Sieve), NFS(Number Field Sieve),타원곡선 알고리즘 및 Pollard's p-1알고리즘 Pollard's rho알로리즘을 분석하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.9-17
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• 2019

In this paper, we propose an attribute-based broadcast encryption algorithm that can be applied to satellite broadcasting network. The encryption algorithm is a cryptographic method by which a carrier(sender) can transmit contents efficiently and securely to a plurality of legitimate users through satellites. An attribute-based encryption algorithm encrypts contents according to property of contents or a user, In this paper, we combine effectively two algorithms to improve the safety and operability of satellite broadcasting network. That is, it can efficiently transmit ciphertexts to a large number of users, and has an advantage in that decoding can be controlled by combining various attributes. The proposed algorithm reduces the network load by greatly reducing the size of the public key, the private key and the cipher text in terms of efficiency, and the decryption operation amount is reduced by half to enable fast decryption, thereby enhancing the operability of the user.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.5 no.1
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• pp.25-36
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• 1995

Differential Cryptanalysis(DC) and Linear Cryptanalysis(LC) are considered to be efficient attack methods which could be applied to DES and other DES-like private key Cryptosystems. This paper analyzes the DC and LC attack to DES and design a 80-bit block Cipher (80-DES) which could be strong against DC and LC Attack.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6B
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• pp.954-961
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• 2010

Stream cipher was worse than block cipher in terms of security, but faster in execution speed as an advantage. However, since so far there have been many algorithm researches about the execution speed of block cipher, these days, there is almost no difference between them in the execution speed of AES. Therefore an secure and fast stream cipher development is urgently needed. In this paper, we propose a 32bit output fast stream cipher, AA32, which is composed of ASR(Arithmetic Shifter Register) and simple logical operation. Proposed algorithm is a cipher algorithm which has been designed to be implemented by software easily. AA32 supports 128bit key and executes operations by word and byte unit. As Linear Feedback Sequencer, ASR 151bit is applied to AA32 and the reduction function is a very simple structure stream cipher, which consists of two major parts, using simple logical operations, instead of S-Box for a non-linear operation. The proposed stream cipher AA32 shows the result that it is faster than SSC2 and Salsa20 and satisfied with the security required for these days. Proposed cipher algorithm is a fast stream cipher algorithm which can be used in the field which requires wireless internet environment such as mobile phone system and real-time processing such as DRM(Digital Right Management) and limited computational environments such as WSN(Wireless Sensor Network).

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.367-370
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• 2024

양자컴퓨터 시대가 눈앞에 도래한 지금 차세대 암호로 주목받고 있는 양자 내성 암호는 다양한 수학적 알고리즘에 안전성을 기반하고 있으나 이 안전성을 위협하는 대표적인 공격 기법 중 하나인 부채널 분석 공격에 대응하기 위한 노력들이 계속되어 왔다. 이 논문에서는 코드 기반 양자 내성 암호를 중심으로 알고리즘에 위협적인 부채널 분석 공격에 대한 연구 동향을 분석하였다. 그리고 NIST 에서 PQC 표준화를 위해 Round 를 진행 중인 후보 중 하나인 코드 기반 알고리즘 MEDS 에 대해 소개하고, MEDS 알고리즘의 최적화를 위해 기존에 연구되었던 코드 기반 암호에 대한 부채널 분석 공격 대응 측면에서의 알고리즘의 안전성 확보라는 보안 비용과 하드웨어 가속 등을 통한 성능 향상이 적절한 조화를 이룰 수 있도록 설계하기 위한 방안에 대해 알아보았다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.700-702
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• 1998

스마트카드 운영체제는 카드와 터미널간의 인증(authentication), 메시지 처리 및 메시지 처리시 비밀성(security) 유지 등의 작업을 수행한다. 본 논문은 스마트카드에서 DES 암호 알고리즘보다 보안성이 뛰어나고, 다양한 응용을 지원하기 위해서 RSA 암호 알고리즘을 이용한 확장 가능한 운영체제를 구현한다. 스마트카드 시스템과 운영체제의 구조는 ISO/IEC 7816 규정을 따르고 있었고, 몽고메리 알고리즘을 이용한 RSA 암호 알고리즘은 스마트카드에서 인증과 스마트카드 내에서 파일의 보안성, 메시지 보안 명령어를 안전하게 수행한다. 본 논문에서 제시한 스마트카드 운영체제는 다양한 응용을 지원하기 위하여 응용 목적에 따라 운영체제와 응용 프로그램을 확장할 수 있게 설계되었다.

• Review of KIISC
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• v.33 no.1
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• pp.13-21
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• 2023

NIST는 2022년 양자내성암호 표준화 진행 대상 알고리즘으로 KEM 1종(CRYSTALS-Kyber), 전자서명3종(CRYSTALS-Dilithium, FALCON, SPHINCS+)을 발표하였고, 추가로 KEM 4종(Classic McEliece, HQC, BIKE, SIKE)에 대한 Round 4 진행을 공표하였다. Round 3와 마찬가지로 Round 4에서도 부채널 분석 및 오류 주입에 대한 안전성은 알고리즘 선정에 있어 중요 평가 사항 중 하나이다. 따라서 해당 암호 알고리즘에 대한 새로운 부채널 분석기술에 대한 연구가 활발히 진행되고 있다. 본 논문은 Round 4의 암호 알고리즘 중 코드 기반 알고리즘 3종(Classic McEliece, HQC, BIKE)에 대한 부채널 분석 방법론의 동향을 파악하고 향후 연구 방향을 제시한다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.4
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• pp.51-57
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• 2003

The development of the communication network and the other network method can generate serious social problems. So, it is highly required to control security of network. These problems related security will be developed and keep up to confront with anti-security field such as hacking, cracking. The way to preserve security from hacker or cracker without developing new cryptographic algorithm is keeping the state of anti-cryptanalysis in a prescribed time by means of extending key-length. In this paper, we proposed M3 algorithm for the reduced processing time in the montgomery multiplication part. Proposed M3 algorithm using the matrix function M(.) and lookup table perform optionally montgomery multiplication with repeated operation. In this result, modified repeated operation part produce 30% processing rate than existed montgomery multiplicator. The proposed montgomery multiplication structured unit array method in carry generated part and variable length multiplication for eliminating bottle neck effect with the RSA cryptosystem. Therefore, this proposed montgomery multiplier enforce the real time processing and prevent outer cracking.

• Journal of the Korea Computer Industry Society
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• v.10 no.4
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• pp.167-176
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• 2009

In this paper, we propose an improved SHACAL-1 of the same encryption and decryption with a simple symmetric layer. SHACAL-1 has 4 rounds, and each round has 20 steps. Decryption is becoming inverse function of encryption, In this paper, we proposed SHACAL-1 are composed of the first half, symmetry layer and the last half. The first half with SHACAL-1 encryption algorithm 1 round does with 10 steps and composes of 4 round. The last half identically with SHACAL-1 decryption algorithm, has a structure. On the center inserts a symmetry layer, encryption and decryption algorithm identically, composes. In the experiments, the proposed SHACAL-1 algorithm showed similar execution time to that of the SHACAL-1. Thanks to the symmetric layer, the proposed algorithm makes it difficult for the attacks which take advantages of high probability path such as the linear cryptanalysis, differential cryptanalysis. The proposed algorithm can be applicable to the other block cipher algorithms which have different encryption and decryption and useful for designing a new block cipher algorithm.