• Convergence Security Journal
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• v.11 no.3
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• pp.25-30
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• 2011

WEP is proposed networks dominate the market in the future wireless LAN encryption and authentication features to provide a secure protocol. However, WEP does not suggest a specific measures when generating the initial values used for the creation cipher text, the initial value problem because tile size and no-encryption if you have been raised about the safety issue. In this paper pointed out the vulnerabilities of WEP and the proposed improvement plan for this improvement was proposed based on the initial value to avoid re-creating the initial value of the system and using a block cipher in CBC mode for confidentiality and to provide mutual authentication New WLAN security model was proposed.

• Journal of the Korea Convergence Society
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• v.9 no.3
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• pp.45-51
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• 2018

According to the report, the World Economic Forum predicted that by 2020, more than 5.3 million jobs will be lost. Among them are accountants and tax accountants as well. Accountancy is a professional practice, accounting for management consulting, accounting audit, and management consultancy, and tax accountant duties are a professional profession that carries out duties such as tax returns and tax laws. Therefore, this study proposes a method to build transparent and safe tax and accounting information by increasing the efficiency of tax and accounting work by building a block chaining accounting and tax information suitable for the fourth industrial revolution era.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.1
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• pp.53-60
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• 2018

Cryptographic algorithms are being standardized globally, and the security of cryptographic algorithms has been well proven. However, there is a need for an improved verification method to verify that the existing verification method is correctly implemented according to the standard, because there is a weakness in implementation and it can cause serious damage. Therefore, in this paper, we selected ARIA and LEA to be verified among 128-bit or more block cipher modules performed by the National Intelligence Service, and propose a method to verify whether it is implemented correctly using Cryptol for high-assurance cryptographic module.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.709-718
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• 2019

A lightweight block cipher CHAM designed for suitability in resource-constrained environment has reasonable security level and high computational performance. Since this cipher may contain intrinsic weakness on side channel attack, it should adopt a countermeasure such as masking method. In this paper, we implement the masked CHAM cipher on 32-bit microprosessor Cortex-M3 platform to resist against side channel attack and analyze their computational performance. Based on the shortcoming of having many round functions, we apply reduced masking method to the implementation of CHAM cipher. As a result, we show that the CHAM-128/128 algorithm applied reduced masking technique requires additional operations about four times.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.4
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• pp.27-35
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• 2008

In this paper we show that the full-round SCO-1[12] is vulnerable to the related-key differential attack. The attack on the full-round SCO-1 requires $2^{61}$ related-key chosen ciphertexts and $2^{120.59}$ full-round SCO-1 decryptions. This work is the first known attack on SCO-1.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.2
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• pp.3-9
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• 2009

In this paper we introduce a new side-channel attack using block cipher cryptanalysis named meet-in-the middle attack. Using our new side-channel technique we introduce side-channel attacks on AES with reduced masked rounds. That is, we show that AES with reduced 10 masked rounds is vulnerable to side channel attacks based on an existing 4-round function. This shows that one has to mask the entire rounds of the 12-round 192-bit key AES to prevent our attacks. Our results are the first ones to analyze AES with reduced 10 masked rounds.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.10 no.4
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• pp.107-112
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• 2000

In this paper, we study a security of HEA(Hangul Encryption Algorithm) against differential cryptanalysis. HEA, which is 1,024bits input/output and 56bits key size, has the same structure as DES(Data Encyption Standard) only for Korean characters to be produced in ciphertexts. An encryption algorithm should be developed to meet certain critria such as input/ouput dependencies, correlation, avalanche effects, etc. However HEA uses the same S-Boxes as DES does and just expands the plaintext/ciphertext sizes . We analysize HEA with a differential cryptanalysis and present two results. The number of rounds of HEA has not been determined in a concrete basis of cryptanalysis and we show a chosen plintext attack of 10 round reduced HEA with a diffe- rential cryptanalysis characteristic.

• Journal of Advanced Navigation Technology
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• v.11 no.1
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• pp.93-98
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• 2007

The importance of information security is increasing by the rapid development of the communication network. So, cryptosystems are used to solve these problems and securities of cryptosystems are dependent on keys. In this paper, we propose a key generation method which is based on cryptographically secure MD5 hash function. The basic structure of the MD5 hash function features is a repetitive structure which is processed in a block unit of 512 bits from inputs of limited length and generates a fixed output of 128 bits. The security of proposed method is based on the hash function and the proposed method can be also utilized for authentication algorithm or data encryption algorithm.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.330-333
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• 2021

2020년 전자서명법 개정으로 공인인증서가 폐지됨에 따라 자체 인증 기술의 도입이 필요한 실정이다. 특히나 COVID-19로 인한 비대면 상황이 지속됨에 따라 기존 아날로그 방식을 통해 대면으로 계약서를 작성하고 수립하는데 많은 비효율적 문제가 대두되었다. 디지털 전환 가속화와 비대면 거래확대로 인한 전자 신원확인 중요성이 점차 커지고 있음에 따라 전자 서명 및 전자 봉투 방식으로 계약할 수 있는 안전한 시스템 개발을 진행하고자 한다. 이를 위해 계약 시스템의 보안 요구 사항을 도출하였으며 최종적으로 NFT 연동을 통해 안전한 계약을 진행할 수 있도록 프로세스를 설계하였다. 시스템의 동작 방식을 표현하기 위하여 DFD 등을 포함한 Diagram 형태로 나타내었으며 실제 프로토타입을 제작 후 블록체인 네트워크에 연결한 뒤 테스트를 진행하여 시스템 검증을 수행하였다. 추후 이 시스템을 통해 B2B, B2C 모델 등의 모델 기반 다양한 거래와 계약이 가능하도록 구성할 예정이며 추가적인 연구를 진행하여 사용자 측면에서 더 간편하고 안전한 환경이 될 수 있도록 고도화 시키는 것을 목표로 한다.

• 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).