• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.6
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• pp.1353-1360
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• 2016

We analyze the efficiency of the double-block-length hash functions, Abreast-DM, HIROSE, MDC-2, MJH, MJH-Double based on AES or LEA. We use optimized open-source code for AES, and our implemented source code for LEA. As a result, the hash functions based on LEA are generally more efficient than those, based on AES. In terms of speed, the hash function with LEA are 6%~19% faster than those with AES except for Abreast-DM. In terms of memory, the hash functions with LEA has 20~30 times more efficient than those with AES.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.183-188
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• 2005

Parallel processing in block cryptographic algorithm is difficult, because Feistel structure that is basis structure of block cryptographic algorithm is sequential processing structure. Therefore this paper changes these sequential processing structure and Feistel structure made parallel processing to be possible. This paper that apply this modified structure designed DES that have parallel Feistel structure. Proposed parallel Feistel structure could prove greatly block cryptographic algorithm's performance such as DES and so on that could not but have trade-off relation the data processing speed and data security interval because block cryptographic algorithm can not use pipeline method because of itself structural problem. Therefore, modified Feistel structure is going to display more superior security function and processing ability of high speed than now in case apply way that is proposed to SEED, AES's Rijndael, Twofish etc. that apply Feistel structure.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.5
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• pp.107-112
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• 2020

Ultra-lightweight password CHAM is an algorithm with efficient addition, rotation and XOR operations on resource constrained devices. CHAM shows high computational performance, especially on IoT platforms. However, lightweight block encryption algorithms used on the Internet of Things may be vulnerable to side channel analysis. In this paper, we demonstrate the vulnerability to side channel attack by attempting a first power analysis attack against CHAM. In addition, a safe algorithm was proposed and implemented by applying a masking technique to safely defend the attack. This implementation implements an efficient and secure CHAM block cipher using the instruction set of an 8-bit AVR processor.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.3-16
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• 2010

Key derivation functions are used within many cryptographic systems in order to generate various keys from a fixed short key string. In this paper we survey a state-of-the-art in the key derivation functions and wish to examine the soundness of the functions on the view point of provable security. Especially we focus on the key derivation functions using pseudorandom functions which are recommended by NISI recently, and show that the variant of Double-Pipeline Iteration mode using pseudorandom permutations is a pseudorandom function. Block ciphers can be regarded as practical primitives of pseudorandom permutations.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.201-204
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• 2021

PIPO 경량 블록암호는 ICISC'20에서 발표된 암호이다. 본 논문에서는 PIPO의 단일 평문 최적화 구현과 4평문 병렬 구현을 제안한다. 단일 평문 최적화 구현은 Rlayer의 최적화와 키스케쥴을 포함하지 않은 구현을 진행하였다. 결과적으로 키스케쥴을 포함하는 기존 연구 대비 70%의 성능 향상을 확인하였다. 4평문의 경우 32-bit 레지스터를 최대한 활용하여, 레지스터 내부 정렬과 Rlayer의 최적화 구현을 진행하였다. 또한 Addroundkey 구현에서 메모리 최적화 구현과 속도 최적화 구현을 나누어 구현하였다. 메모리 사용을 줄인 메모리 최적화 구현은 단일 평문 구현 대비 80%의 성능 향상을 확인하였고, 암호화 속도를 빠르게 구현한 속도 최적화 구현은 단일 평문 구현 대비 157%의 성능 향상을 확인하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.1
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• pp.221-227
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• 2014

When implementing cryptographic algorithms in mobile devices like smart cards, the security against side-channel attacks should be considered. Side-channel attacks try to find critical information from the side-channel infromation obtained from the underlying cryptographic devices' execution. Especially, the power analysis attack uses the power consumption profile of the devices as the side-channel information. This paper proposes a new gate-level countermeasure against the power analysis attack and the glitch attack and suggests how to apply the measure to securely implement AES.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.2
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• pp.309-320
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• 2019

Blockchain has been developed as a key technology for many cryptocurrency systems such as Bitcoin. These days, blockchain technology attracts many people to adopt it to various fields beyond cryptocurrency systems for their information sharing and processing. However, with the development and increasing adoption of the blockchain, security incidents frequently happen in the blockchain systems due to their implementation flaws. In order to solve this problem, in this paper, we analyze the software vulnerabilities of Bitcoin and Ethereum, which are the most widely used blockchain applications in real world. For that purpose, we conduct an in-depth analysis of source code of them to detect software vulnerabilities, and examine an OS command injection attack exploiting the detected ones.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.10
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• pp.89-96
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• 2003

In this paper, a CCSDS(Consultative Committee for Space Data Systems) telecommand(TC) decryptor for the security of geostationary communications satellite was implemented. For the confidentiality of CCSDS TC datalink security, Option-A which implements the security services below the transfer sublayer was selected. Also CFB(Cipher Feedback) operation mode of DES(Data Encryption Standard) was used for the encryption of 56-bit data bits in 64-bit codeblock. To verify Decryptor function, the DES CFB logic implemented on A54SX32 FPGA(Field Programmable Gate Array) was integrated with interface and control logics in a PCB(Printed Circuit Board). Using a function test PC, the encrypted codeblocks were generated, transferred into the decryptor, decrypted, and the decrypted codeblocks were transmitted to the function test PC, and then compared with the source codeblocks. Through LED(Light Emitting Diode) ON operation by driving the relay related to Op-code decoded and the comparison between the codeblock output waveforms measured and those simulated, the telecommand decryptor function was verified.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1462-1470
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• 2003

According to the necessity about information security as well as the advance of IT system and the spread of the Internet, a variety of cryptography algorithms are being developed and put to practical use. In addition the technique about cryptography attack also is advanced, and the algorithms which are strong against its attack are being studied. If the linear transformation matrix in the block cipher algorithm such as Substitution Permutation Networks(SPN) produces the Maximum Distance Separable(MDS) code, it has strong characteristics against the differential attack and linear attack. In this paper, we propose a new algorithm which cm estimate that the linear transformation matrix produces the MDS code. The elements of input code of linear transformation matrix over GF$({2_n})$ can be interpreted as variables. One of variables is transformed as an algebraic formula with the other variables, with applying the formula to the matrix the variables are eliminated one by one. If the number of variables is 1 and the all of coefficient of variable is non zero, then the linear transformation matrix produces the MDS code. The proposed algorithm reduces the calculation time greatly by diminishing the number of multiply and reciprocal operation compared with the conventional algorithm which is designed to know whether the every square submatrix is nonsingular.

• Convergence Security Journal
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• v.19 no.1
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• pp.49-60
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• 2019

Medical record is part of the personal information that values the dignity and value of an individual, and can lead to serious social prejudice and disadvantage to an individual when it is breached illegally. In addition, the medical record has been highly threatened because its value is relatively high, and external threats are continuing. In this paper, we propose a medical record sharing framework that guarantees patient's privacy based on blockchain using ciphertext policy-based attribute based proxy re-encryption scheme. The proposed framework first uses the blockchain technology to ensure the integrity and transparency of medical records, and uses the stealth address to build the unlinkability between physician and patient. Besides, the ciphertext policy attribute-based proxy re-encryption scheme is used to enable fine-grained access control, and it is possible to share information in emergency situations without patient's agreement.